PROJECT DOCUMENT OF PERVIOUS CONCRETE

A PROJECT REPORT
ON
“IMPROVEMENT OF COMPRESSIVE STRENGTH OF PERVIOUS
CONCRETE”
Submitted in partial fulfilment of the requirements for the award of the Degree of
BACHELOR OF TECHNOLOGY
IN
CIVIL ENGINEERING
Submitted by
G.AJITH KUMAR (13711A0122)
B.S.V. DINESH (13711A0103)
G.VAMSI KRISHNA (13711A0120)
K.TEJA SREENIVAS (13711A0129)
K.VINAY KUMAR (13711A0131)
Under the esteemed Guidance of
Mr. SK.FAYAZ M.tech
Department of Civil Engineering
DEPARTMENT OF CIVIL ENGINEERING
NARAYANA ENGINEERING COLLEGE
[An ISO 9001:2008 Certified]
[Recognized by A.I.C.T.E., Affiliated to J.N.T.U., Anantapur]
NELLORE, Nellore-524 001(A.P.), India
2013-2017
NARAYANAENGINEERINGCOLLEGE::NELLORE

[Recognized by A.I.C.T.E., Affiliated to J.N.T.U., Anantapur]
DEPARTMENT OF CIVIL ENGINEERING
CERTIFICATE
The is to certify that the project report entitled “IMPROVEMENT OF COMPRESSIVE
STRENGTH OF PERVIOUS CONCRETE " being submitted by
B.S.V. DINESH (13711A0103)
In partial fulfilment of the requirements for the award of degree of BACHELOR OF
TECHNOLOGY IN CIVIL ENGINEERING of Jawaharlal Nehru Technical
University, Anantapur is a bonafied work carried out by them under my guidance and
supervision during the academic year 2013-2017. The results presented in this project
have not been submitted to any other university or institute for the award of any degree
or diploma.
Mr. SK.FAYAZ.M.Tech Dr. K.YUGANDHAR REDDYM.Tech,Ph.D
Assistant Professor HEAD OF THE DEPARTMENT
Department of Civil Engineering Department of Civil Engineering
Narayana Engineering College Narayana Engineering College
Nellore Nellore
Date of Viva-Voice: 24-04-2017
INTERNAL EXAMINER EXTERNAL EXAMINER
ACKNOWLEDGEMENT
We would like express our deep sense of gratitude to our project guide
Mr.Sk.FAYAZ, Assistant professor, Department of civil engineering, who has guided

our work with scholarly advice and meticulous care. He had shown keen interest and
personal care at every stage of our project.
We are profoundly thankful to Project Coordinator Mr. Sk.RASHID, Assistant
professor, Department of civil engineering for his moral support and to
Prof.K.YUGANDHAR REDDYM.Tech,Ph.D, Professor & Head of the Department of civil
engineering, for his cooperation and encouragement.
We wish to express our sincere thanks to Dr. B.V.RAMANA REDDY, Principal
for his kind gesture and support. We are indebted to the Management of Narayana
engineering college, Nellore for providing the necessary infrastructure and good
academic environment in an endeavour to complete the project.
We are extremely grateful to Dr. P.NARAYANAPh.D., Chairman, Narayana
Educational Institutions, Andhra Pradesh for his good blessings.
We are thankful to the lab technicians of Department of Civil Engineering for
their co-operation during the project.
Finally, we like to thank our parents, friends and the people who directly and
indirectly helped us for the successful completion of project.
Project Associates
B.S.V. DINESH (13711A0103)

ABSTRACT
Pervious concrete is a special type of concrete, which consists of cement, coarse aggregates,
water and if required, admixtures and other cementitious materials. As there are no fine aggregates used
in the concrete matrix, the void content is more which allows the water to flow through its body. So the
pervious concrete is also called as Permeable concrete and Porous concrete.
There is lot of research work is going in the field of pervious concrete. The compressive
strength of pervious concrete is less when compared to the conventional concrete due to its porosity and
voids. Hence, the usage of pervious concrete is limited even though it has lot of advantages. If the
compressive strength and flexural strength of pervious concrete is increased, then it can be used for
more number of applications. For now, the usage of pervious concrete is mostly limited to light traffic
roads only. If the properties are improved, then it can also be used for medium and heavy traffic rigid
pavements also. Along with that, the pervious concrete eliminates surface runoff of storm water,
facilitates the ground water recharge and makes the effective usage of available land.
The main aim of our project is to improve the strength characteristics of pervious concrete. But
it can be noted that with increase in strength, the permeability of pervious concrete will be reduced.
Hence, the improvement of strength should not affect the permeability property because it is the
property which serves its purpose.

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Chapter-1
INTRODUCTION
1.1 Introduction:
Pervious concrete which is also known as the no-fines, porous, gap-graded, and
permeable concrete and Enhance porosity concrete have been found to be a reliable storm
water management tool. By definition, pervious concrete is a mixture of gravel or granite
stone, cement, water, little to no sand (fine aggregate). When pervious concrete is used for
paving, the open cell structures allow storm water to filter through the pavement and into the
underlying soils. In other words, pervious concrete helps in protecting the surface of the
pavement and its environment.
As stated above, pervious concrete has the same basic constituents as conventional
concrete, 15 -30% of its volume consists of interconnected void network, which allows water
to pass through the concrete. Pervious concrete can allow the passage of 11.35-18.97 liters of
water per minute through its open cells for each square foot (0.0929m2) of surface area which
is far greater than most rain occurrences. Apart from being used to eliminate or reduce the
need for expensive retention ponds, developers and other private companies are also using it
to free up valuable real estate for development, while still providing a paved park.
Pervious concrete is also a unique and effective means to address important
environmental issues and sustainable growth. When it rains, pervious concrete automatically
acts as a drainage system, thereby putting water back where it belongs. Pervious concrete is
rough textured, and has a honeycombed surface, with moderate amount of surface ravelling
which occurs on heavily travelled roadways. Carefully controlled amount of water and
cementitious materials are used to create a paste. The paste then forms a thick coating around
aggregate particles, to prevent the flowing off of the paste during mixing and placing. Using
enough paste to coat the particles maintain a system of interconnected voids which allow
water and air to pass through. The lack of sand in pervious concrete results in a very harsh
mix that negatively affects mixing, delivery and placement. Also, due to the high void
content, pervious concrete is light in weight (about 1600 to 2000 kg/m3). Pervious concrete

6
void structure provides pollutant captures which also add significant structural strength as
well. It also results in a very high permeable concrete that drains quickly.
Pervious concrete can be used in a wide range of applications, although its primary
use is in pavements which are in: residential roads, alleys and driveways, low volume
pavements, low water crossings, sidewalks and pathways, parking areas, tennis courts, slope
stabilisation, sub-base for conventional concrete pavements etc.,
Figure1.1: pervious concrete cube blocks

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Figure1.2: Pervious concrete beam
Pervious concrete system has advantages over impervious concrete in that it is
effective in managing run-off from paved surfaces, prevent contamination in run-off water,
and recharge aquifer, repelling salt water intrusion, control pollution in water seepage to
ground water recharge thus, preventing subterranean storm water sewer drains, absorbs less
heat than regular concrete and asphalt, reduces the need for air conditioning. Pervious
concrete allows for increased site optimization because in most cases, its use should totally
limit the need for detention and retention ponds, swales and other more traditional storm
water management devices that are otherwise required for compliances with the Federal
storm water regulations on commercial sites of one acre or more. By using pervious concrete,
the ambient air temperature will be reduced, requiring less power to cool the building. In
addition, costly storm water structures such as piping, inlets and ponds will be eliminated.
Construction scheduling will also be improved as the stone recharge bed will be installed at
the beginning of construction, enhancing erosion control measures and preventing rain delays
due to harsh site conditions. Apparently, when compared to conventional concrete, pervious
concrete has a lower compressive strength, greater permeability, and a lower unit weight
(approximately 70% of conventional concrete). However, pervious concrete has a greater
advantage in many regards. Nevertheless, it has its own limitations which must be put in
effective consideration when planning its use. Structurally when higher permeability and low
strength are required, the effect of variation in aggregate size on strength and permeability for
the same aggregate cement ratio need to be investigated.

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Figur1.3: water flowing through pervious concrete cube
1.2 Brief History:
Pervious Concrete has been around for hundreds of years. The Europeans recognized
the insulating properties in structural pervious concrete for their buildings. Europeans have
also used pervious concrete for paving. Stories passed down through the years tell us that
soldiers didn’t mind walking on pervious roads during World War II because it meant their
feet would be dry.
Pervious was brought to the United States after World War II. It first showed up in
Florida and other southern coastal states. Slowly it has migrated to the other states where it
has met different successes. As with any new product, it has had to prove itself. Many well
intended ready mix producers have produced the product and many well intended contractors
have placed the product. Some did well, others did not. As it is true with any material and
construction technique, there is a science to it and a best way to conduct the construction.
Education and experience is the key to success. The coastal states have experienced pervious
concrete for over 20 years. The hesitation to move into the Midwest and Northern States was
mainly due to freeze/thaw concerns. Now that those concerns are no longer considered a
problem, the product has moved quickly across the United States.
In the 1990’s the U.S. Environmental Protection Administration (EPA) came out with
the Clean Water Act (CWA), that later led to other phases of implementation to preserve the
waterways from stormwater borne pollutants. EPA identifies “stormwater runoff is generated
when precipitation from rain and snowmelt events flow over land or impervious surfaces and
does not percolate into the ground. As the runoff flows over the land or impervious surfaces
(paved streets, parking lots, and building rooftops), it accumulates debris, chemicals,
sediment or other pollutants that could adversely affect water quality if the runoff is
discharged untreated. The primary method to control stormwater discharges is the use of best
management practices (BMPs).” (EPA.gov). Pervious concrete is one of many BMP’s
recognized by the EPA as well as our local American Public Works Association (APWA) and
the Mid America Regional Council (MARC). Basically, it requires the developer/owner to
keep as much stormwater on property as possible. If stormwater leaves the property it must
leave cleaner and cooler than before. Pervious concrete allows for the filtering/cleaning and
detainment of stormwater.

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1.3 General Properties of Pervious Concrete:
The plastic pervious concrete mixture is stiff compared to traditional concrete.
Slumps, when measured, are generally less than 20mm, although slumps as high as 50mm
have been used. However, slump of pervious concrete has no correlation with its workability
and hence should not be specified as an acceptance criterion. Typical densities and void
contents are on the order of 1600 kg/m3 to 2000 kg/m3 and 20 to 25% respectively. The
infiltration rate (permeability) of pervious concrete will vary with aggregate size and density
of the mixture, but will fall into the range of 80 to 720 litres per minute per square meter. A
moderate porosity pervious concrete pavement system will typically have a permeability of
143 litres per minute per square meter. Perhaps nowhere in the world would one see such a
heavy rainfall. In contrast the steady state infiltration rate of soil ranges from 25 mm/hr to
0.25 mm/hr. This clearly suggests that unless the pervious concrete is severely clogged up
due to possibly poor maintenance it is unlikely that the permeability of pervious concrete is
the controlling factor in estimating runoff (if any) from a pervious concrete pavement. For a
given rainfall intensity the amount of runoff from a pervious concrete pavement system is
controlled by the soil infiltration rate and the amount of water storage available in the
pervious concrete and aggregate base (if any) under the pervious concrete.
Generally for a given mixture proportion strength and permeability of pervious
concrete are a function of the concrete density. Greater the amount of consolidation higher
the strength, and lower the permeability. Since it is not possible to duplicate the in-place
consolidation levels in a pervious concrete pavement one has to be cautious in interpreting
the properties of pervious concrete specimens prepared in the laboratory. Such specimens
may be adequate for quality assurance namely to ensure that the supplied concrete meets
specifications. Core testing is recommended for knowing the in-place properties of the
pervious concrete pavement. The relationship between the w/cm and compressive strength of
conventional concrete is not significant. A high w/cm can result in the paste flowing from the
aggregate and filling the void structure. A low w/cm can result in reduced adhesion between
aggregate particles and placement problems. Flexural strength in pervious concretes generally
ranges between about 1 MPa and 3.8 MPa. Numerous successful projects have been
successfully executed and have lasted several winters in harsh Northern climates. This is
possibly because pervious concrete is unlikely to remain saturated in the field.

10
The freeze thaw resistance of pervious concrete can be enhanced by the following measures
1. Use of fine aggregates to increase strength and slightly reduce voids content to about 20%.
2. Use of air-entrainment of the paste.
3. Use of a perforated PVC pipe in the aggregate base to capture all the water and let it drain
away below the pavement. Abrasion and ravelling could be a problem. Good curing practices
and appropriate w/cm (not too low) is important to reduce ravelling. Where as severe
ravelling is unacceptable some loose stones on a finished pavement is always expected. Use
of snow ploughs could increase ravelling. A plastic or rubber shield at the base of the plough
blade may help to prevent damage to the pavement.
1.4 Benefits of Pervious Concrete:
Pervious concrete pavement systems provide a valuable stormwater management tool
under the requirements of the EPA Storm Water Phase II Final Rule Phase II regulations
provide programs and practices to help control the amount of contaminants in our waterways.
Impervious pavement particularly parking lots collect oil, anti-freeze, and other automobile
fluids that can be washed into streams, lakes, and oceans when it rains. EPA Storm Water
regulations set limits on the levels of pollution in our streams and lakes. To meet these
regulations, local officials have considered two basic approaches. They are
1) Reduce the overall runoff from an area
2) Reduce the level of pollution contained in runoff
Efforts to reduce runoff include zoning ordinances and regulations that reduce the amount of
impervious surfaces in new developments (including parking and roof areas), increased green
space requirements, and implementation of “stormwater utility districts” that levy an impact
fee on a property owner based on the amount of impervious area. Efforts to reduce the level
of pollution from stormwater include requirements for developers to provide systems that
collect the “first flush” of rainfall, usually about 25 mm, and “treat” the pollution prior to
release. Pervious concrete pavement reduces or eliminates runoff and permits “treatment” of
pollution: two studies conducted on the long-term pollutant removal in porous pavements
suggest high pollutant removal rates. By capturing the first flush of rainfall and allowing it to
percolate into the ground, soil chemistry and biology are allowed to “treat” the polluted water
naturally. Thus, stormwater retention areas may be reduced or eliminated, allowing increased

11
land use. Furthermore, by collecting rainfall and allowing it to infiltrate, groundwater and
aquifer recharge is increased, peak water flow through drainage channels is reduced and
flooding is minimized. In fact, the EPA named pervious pavements as a BMP for stormwater
pollution prevention (EPA 1999) because they allow fluids to percolate into the soil. Another
important factor leading to renewed interest in pervious concrete is an increasing emphasis on
sustainable construction. Because of its benefits in controlling stormwater runoff and
pollution prevention, pervious concrete has the potential to help earn a credit point in the U.S.
Green Building Council’s Leadership in Energy & Environmental Design (LEED) Green
Building Rating System, increasing the chance to obtain LEED project certification. This
credit is in addition to other LEED credits that may be earned through the use of concrete for
its other environmental benefits, such as reducing heat island effects recycled content and
regional materials. The light colour of concrete pavements absorbs less heat from solar
radiation than darker pavements, and the relatively open pore structure of pervious concrete
stores less heat, helping to lower heat island effects in urban areas. Trees planted in parking
lots and city sidewalks offer shade and produce a cooling effect in the area, further reducing
heat island effects. Pervious concrete pavement is ideal for protecting trees in a paved
environment. (Many plants have difficulty growing in areas covered by impervious
pavements, sidewalks and landscaping, because air and water have difficulty getting to the
roots.) Pervious concrete pavements or sidewalks allow adjacent trees to receive more air and
water and still permit full use of the pavement pervious concrete provides a solution for
landscapers and architects who wish to use greenery in parking lots and paved urban areas.
Although high-traffic pavements are not a typical use for pervious concrete, concrete surfaces
also can improve safety during rainstorms by eliminating ponding (and glare at night),
spraying, and risk of hydroplaning.

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1.5 Major applications of pervious concrete:
 Low-volume pavements
 Residential roads, alleys, and driveways
 Sidewalks and pathways
 Parking areas
 Low water crossings
 Tennis courts
 Sub base for conventional concrete pavements
 Slope stabilization
 Well linings
 Hydraulic structures
 Swimming pool decks
 Pavement edge drains and Tree grates in sidewalks
 Groins and seawalls
 Noise barriers
 Walls (including load-bearing)

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Chapter-2
LITERATURE REVIEW
2.1 Background:
Portland cement pervious concrete (PCPC) has great potential to reduce roadway
noise, improve splash and spray, and improve friction as a surface wearing course. A
pervious concrete mix design for a surface wearing course must meet the criteria of adequate
strength and durability under site-specific loading and environmental conditions. To date, two
key issues that have impeded the use of pervious concrete in the United States are that
strengths of pervious concrete have been lower than necessary for required applications and
the freeze-thaw durability of pervious concrete has been suspect. A research project on the
freeze-thaw durability of pervious concrete mix designs at Iowa State University (ISU) has
recently been completed (Schaefer et al. 2006). The results of this study have shown that a
strong, durable pervious concrete mix design that will withstand wet, hard- freeze
environments is possible. The strength is achieved through the use of a small amount of fine
aggregate (i.e., concrete sand) and/or latex admixture to enhance the particle-to-particle bond
in the mix. The preliminary results were reported in Kevern et al. (2005).
The recent work has been limited to laboratory testing and to only a few mixes using
two sources of aggregates. Preliminary laboratory testing has shown the importance of
compaction energy on the properties and performance of the mixes, an issue that has direct
bearing on the construction technique used to place the materials in the field. Tests conducted
in Purdue University’s Tire-Pavement Test Apparatus showed reduced noise levels above
1,000 hertz (Hz) and some increase in noise levels below 1,000 Hz. The increased porosity of
pervious concrete increased mechanical excitation and interaction between the tire and
pavement at frequencies below about 1,000 Hz and at frequencies above about 1,000 Hz; the
air pumping mechanics that dominate at such frequencies are relieved by the increased
porosity leading to decreased high-frequency noise levels.
A recent European Scan (sponsored by the Federal Highway Administration/FHWA)
indicated that the use of pervious pavements as friction courses is declining, due to the
European preference toward an exposed aggregate concrete. Also, clogging, ravelling, and
winter maintenance were indicated as problem areas. Participants in the Scan felt that the use
of pervious concrete was not given enough time to develop into a viable paving alternative.

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The American experience with pervious concrete is limited. It is important to ascertain what
material elements can be included in the pervious mix design to address the ravelling and
clogging issues. If winter maintenance elements and concerns cannot be overcome, pervious
concrete may be able to be used in warm weather regions
The National Concrete Pavement Technology Centre (National CP Tech Centre) at
ISU developed a research project titled “An Integrated Study of Portland Cement Pervious
Concrete for Wearing Course Applications.” The objective of the research was to conduct a
comprehensive study focused on the development of pervious concrete mix designs having
adequate strength and durability for wearing course pavements and having surface
characteristics that reduce noise and enhance skid resistance while providing adequate
removal of water from the pavement surface and structure. A range of mix designs was used
necessary to meet requirements for wearing course applications. Further, constructability
issues for wearing course sections were addressed to ensure that competitive and economical
placement of the pervious concrete can be done in the field. The focus of the National CP
Tech Centre’s work on pervious concrete was the development of a durable wearing course
that can be used in highway applications for critical noise, splash/spray, skid resistance, and
environmental concerns. The comprehensive study is anticipated to be conducted over a five-
year period and is further described below.
2.2 Strength development of pervious concrete:
A recent National CP Tech Centre report titled Mix Design Development for Pervious
Concrete in Cold Weather Climates (Schaefer et al. 2006) provides a summary of the
available literature concerning the construction materials, material properties, surface
characteristics, pervious pavement design, construction, maintenance, and environmental
issues for PCPC. The primary goal of the research conducted was to develop a pervious
concrete that would provide freeze- thaw resistance while maintaining adequate strength and
permeability for pavement applications.
The key findings from the literature review can be summarized as follows: The
engineering properties reported in the literature from the United States indicate a high void
ratio, low strength, and limited freeze-thaw test results. It is believed that these reasons have
hindered the use of pervious concrete in the hard wet freeze regions (i.e., Midwest and
Northeast United States). The typical mix design of pervious concrete used in the United
States consists of cement, single-sized coarse aggregate (i.e., between 25mm and 100mm),

15
and water to cement ratio ranging from 0.27 to 0.43. The 28-day compressive strength of
pervious concrete ranges from 5 to 20 MPa, with a void ratio ranging from 14% to 31% and a
permeability ranging from 0.025 to 0.6 cm/sec. The advantages of pervious concrete include
improving skid resistance by removing water that creates splash and spray during
precipitation events, reducing noise, minimizing heat islands in large cities, preserving native
ecosystems, and minimizing cost in some cases. Surface coarse pervious concrete pavement
systems have been reported to be used in Europe and Japan. Studies have shown that pervious
concrete generally produces a quieter than normal concrete with noise levels ranging from
3% to 10% lower than those of normal concrete.
The research conducted at ISU included studies of the materials used in the pervious
concrete, the mix proportions and specimen preparation, the resulting strength and
permeability, and the effects of freeze-thaw cycling. A variety of aggregate sizes was tested
and both limestone aggregates and river run gravels were used. The key parameters
investigated were strength, permeability, and freeze-thaw resistance. It can be seen that as the
void ratio increases, the strength decreases but the permeability increases. Shown in the
figure is a target range of void ratio between 15% and 19% in which the strength and
permeability are sufficient for the intended purpose. Subsequent freeze-thaw tests showed
that a durable mix can be developed is Key to the development of a mix that would provide
sufficient strength, adequate permeability, and freeze-thaw resistance was the addition of a
small amount of sand, about 5% to 7%, that increased the bonding of the paste to the
aggregates.
The laboratory studies also raised the issue of compaction energy on the results. The
difference between the compaction energies related to the amplitude of the vibrating pan,
while the frequency was constant. The results of comparisons of two compaction energies
used in the laboratory, and it can be seen that higher compaction energy results in stronger
mixes at given void ratios. These results point to the importance of proper compaction in the
field. A number of field sites have also been investigated and the results are reported in the
master’s thesis by Kevern (2006). Samples from a Sioux City, Iowa site showed more
uniform compaction in the top 150mm, with low compaction causing high voids and low
strength in the bottom layer. A mix proposed for a site in North Liberty, Iowa showed that
limestone mixes with unit weight less than 2000kg/m3 can be freeze-thaw resistant.

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Chapter-3
EXPERIMENTAL WORK
3.1 MATERIALS USED:
3.1.1 CEMENT:
Cement is a key to infrastructure industry and is used for various purposes and also
made in many compositions for a wide variety of uses. Cements may be named after the
principal constituents, after the intended purpose, after the object to which they are applied or
after their characteristic property. Cement used in construction are sometimes named after
their commonly reported place of origin, such as Roman cement, or for their resemblance to
other materials, such as Portland cement, which produces a concrete resembling the Portland
stone used for building in Britain. The term cement is derived from the Latin word
Caementum, which is meant stone chippings such as used in Roman mortar not-the binding
material itself. Cement, in the general sense of the word, described as a material with
adhesive and cohesive properties, which make it capable of bonding mineral fragments in to a
compact whole. The first step of reintroduction of cement after decline of the Roman Empire
was in about 1790, when an Englishman, J.Smeaton, found that when lime containing a
certain amount of clay was burnt, it would set under water. This cement resembled that which
had been made by the Romans. Further investigations by J. Parker in the same decade led to
the commercial production of natural hydraulic cement.
Table 3.1: Typical composition of ordinary Portland cement
Name of compound Chemical Composition Abbreviation
Tricalcium Silicate 3CaO.SiO2 C3S
Dicalcium Silicate 2CaO.SiO2 C2S
Tricalcium aluminate 3CaO.Al2O3 C3A
Tetracalcium alumino ferrite 4CaO.Al2O3.Fe2O3 C4AF

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Figure3.1: Ordinary Portland cement
These compounds interact with one another in the kiln to form a series of more
complex products. Portland cement is varied in type by changing the relative proportions of
its four predominant chemical compounds and by the degree of fineness of the clinker
grinding.
A small variation in the composition or proportion of its raw materials leads to a large
variation in compound composition Calculation of the potential composition of Portland
cement is generally based on the Bogue composition (R.H Bogue). In addition to the main
compounds, there exist minor compounds such as MgO, TiO2, K2O and Na2O; they usually
amount to not more than a few percent of the mass of the cement. Two of the minor
compounds are of particular interest: the oxides of sodium and potassium known as the
alkalis. They have been found to react with some aggregates, the products of the reaction
causing disintegration of the concrete and have also observed to affect the rate of gain of
strength of cement. Present knowledge of cement chemistry indicates that the major cement
compounds have the following properties.
 Tricalcium Silicate, C3S hardens rapidly and is largely responsible for initial set and
early strength development. The early strength of Portland cement concrete is higher
with increased percentages of C3S.
 Dicalcium Silicate, C2S hardens slowly and contributes largely to strength increase at
ages beyond one week.

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 Tricalcium aluminate, C3A liberates a large amount of heat during the first days of
hardening. It also contributes slightly for early strength development. Cements with
low percentages of this compound are especially resistant to soils and waters
containing sulphates. Concrete made of Portland cement with C3A contents as high as
10.0%, and sometimes greater, has shown satisfactory durability, provided the
permeability of the concrete is low.
 Tetracalcium Alumina ferrite, C4AF reduces the clinkering temperature. It will act
as a flux in burning the clinker. It hydrates rather rapidly but contributes very little to
strength development. Most colour effects are due to C4AF series and its hydrates.
The compounds Tricalcium aluminate and Tricalcium silicate develop the greatest
heat, then follows Tetracalcium alumino ferrite, with dicalcium silicate developing the
least heat of all.
In our project work, we have used Ordinary Portland Cement (OPC) of grade 53. It is
a higher strength cement to meet the needs of the consumer for higher strength concrete. As
per BIS requirements the minimum 28 days compressive strength of 53 Grade OPC should
not be less than 53 MPa. For certain specialised works, such as pre stressed concrete and
certain items of precast concrete requiring consistently high strength concrete, the use of 53
grade OPC is found very useful. 53 grade OPC produces higher-grade concrete at very
economical cement content. In concrete mix design, for concrete M-20 and above grades a
saving of 8 to 10 % of cement may be achieved with the use of 53 grade OPC. Ordinary
Portland Cement (OPC) 53 Grade should surpass the requirements of IS: 12269-1987 Grade.
It is produced by inter grinding of high grade clinker (with high C3S content) and right
quality gypsum in predetermined proportions. It is recognized for its high early strength and
excellent ultimate strength because of its optimum particle size distribution, superior
crystalline structure and balanced phase composition and hence widely used and suitable for
speedy construction, durable concrete and economic concrete mix designs.

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3.1.1.1 Advantages:
 Superior quality ensures substantial savings in cement consumption
 Development of very high compressive strength in early stages helps in early de-
shuttering
 Superior resistance to sulphate attack due to less C3A content
 Durable Concrete
 Feasible for economical concrete mix designs
 Low percentage of alkalies, chlorides, magnesia and free lime results in longer life of
concrete structures.
3.1.2 AGGREGATES:
3.1.2.1 Coarse aggregates:
Aggregates were first considered to simply be filler for concrete to reduce the amount
of cement required. However, it is now known that the type of aggregate used for concrete
can have considerable effects on the plastic and hardened state properties of concrete. They
can form 80% of the concrete mix so their properties are crucial to the properties of concrete.
Aggregates can be broadly classified into four different categories: these are heavyweight,
normal weight, lightweight and ultra-lightweight aggregates. However in most concrete
practices only normal weight and lightweight aggregates are used. The other types of
aggregates are for specialist uses, such as nuclear radiation shielding provided by
heavyweight concrete and thermal insulation using lightweight concrete.
3.1.2.1.1 Classification of aggregates:
The alternative used in the manufacture of good quality concrete, is to obtain the
aggregate in at least two size groups, i.e.:
 Fine aggregate often called sand which are less than 4.75mm in size.
 Coarse aggregate, which comprises material greater than 4.75mm in size.

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On the other hand, there are some properties possessed by the aggregate but absent in the
parent rock: particle shape and size, surface texture, and absorption. All these properties have
a considerable influence on the quality of the concrete, either in fresh or in the hardened state.
It has been found that aggregate may appear to be unsatisfactory on some count but no
trouble need be experienced when it is used in concrete
3.1.2.1.2 Aggregate properties:
By selecting different sizes and types of aggregates and different ratios of aggregate
to cement ratios, a wide range of concrete can be produced economically to suit different
requirements. Important properties of an aggregate which affect the performance of a
concrete are discussed as follows:
Figure3.2: 20mm coarse aggregates
3.1.2.1.3 Sampling:
Samples shall be representative and certain precautions in sampling have to be made.
No detailed procedures can be laid down as the conditions and situations involved in taking
samples in the field can vary widely from case to case. Nevertheless, a user can obtain
reliable results bearing in mind that the sample taken is to be representative of the bulk of the
material. The main sample shall be made up of portions drawn from different parts of the
whole. In the case of stockpiles, the sample obtained is variable or segregated, a large number
of increments should be taken and a larger sample should be dispatched for testing.

21
3.1.2.1.4 Particle shape and texture:
Roundness measures the relative sharpness or angularity of the edges and corners of a
particle. Roundness is controlled largely by the strength and abrasion resistance of the parent
rock and by the amount of wear to which the particle has been subjected. In the case of
crushed aggregate, the particle shape depends not only on the nature of the parent rock but
also on the type of crusher and its reduction ratio, i.e. the ratio of the size of material fed into
the crusher to the size of the finished product. Particles with a high ratio of surface area to
volume are also of particular interest for a given workability of the control mix. Elongated
and flaky particles are departed from equi-dimensional shape of particles and have a larger
surface area and pack in an isotropic manner.
Flaky particles affect the durability of concrete, as the particles tend to be oriented in
one plane, with bleeding water and air voids forming underneath. The flakiness and
elongation tests are useful for general assessment of aggregate but they do not adequately
describe the particle shape. The presence of elongated particles in excess of 10 to 15% of the
mass of coarse aggregate is generally undesirable, but no recognized limits are laid down
.Surface texture of the aggregate affects its bond to the cement paste and also influence the
water demand of the mix, especially in the case of fine aggregate. The shape and surface
texture of aggregate influence considerably the strength of concrete. The effects of shape and
texture are particularly significant in the case of high strength concrete.
The full role of shape and texture of aggregate in the development of concrete
strength is not known, but possibly a rougher texture results in a larger adhesive force
between the particles and the cement matrix. The shape and texture of fine aggregate have a
significant effect on the water requirement of the mix made with the given aggregate. If these
properties of fine aggregate are expressed indirectly by its packing, i.e. by the percentage
voids in a loose condition, then the influence on the water requirement is quite definite. The
influence of the voids in coarse aggregate is less definite. Flakiness and shape of coarse
aggregates have an appreciable effect on the workability of concrete.

22
3.1.2.1.5 Bond of aggregate:
Bond between aggregate and cement paste is an important factor in the strength of
concrete, but the nature of bond is not fully understood. Bond is to the interlocking of the
aggregate and the hydrated cement paste due to the roughness of the surface of the former. A
rougher surface, such as that of crushed particles, results in a better bond due to mechanical
interlocking; better bond is not usually obtained with softer, porous, and minor logically
heterogeneous particles. Bond is affected by the physical and chemical properties of
aggregate. For good development of bond, it is necessary that the aggregate surface be clean
and free from adhering clay particles .The determination of the quality of bond of aggregate
is difficult and no accepted tests exist. Generally, when bond is good, a crushed specimen of
normal strength concrete should contain some aggregate particles broken right through, in
addition to the more numerous ones pulled out from their sockets. An excess of fractured
particles, might suggest that the aggregate is too weak.
3.1.2.1.6 Strength of aggregate:
The compressive strength of concrete cannot significantly exceed that of the major
part of the aggregate contained. If the aggregate under test leads to a lower compressive
strength of concrete, and in particular if numerous individual aggregate particles appear
fractured after the concrete specimen has been crushed, then the strength of the aggregate is
lower than the nominal compressive strength of the concrete mix. Such aggregate can be used
only in a concrete of lower strength. The influence of aggregate on the strength of concrete is
not only due to the mechanical strength of the aggregate but also, to a considerable degree, to
its absorption and bond characteristics. In general, the strength of aggregate depends on its
composition, texture and structure. Thus a low strength may be due to the weakness of
constituent grains or the grains may be strong but not well knit or cemented together. A test
to measure the compressive strength of prepared rock cylinders used to be prescribed.
However, the results of such a test are affected by the presence of planes of weakness in the
rock that may not be significant once the rock has been reduced to the size used in concrete.
In essence the crushing strength test measures the quality of the parent rock rather than the
quality of the aggregate as used in concrete. For this reason the test is rarely used. Crushing
value test BIS: 812-1990, measures the resistance to pulverization. There is no obvious
physical relation between this crushing value and the compressive strength, but the results of
the two tests are usually in agreement.

23
3.1.2.1.7 Deleterious substances of aggregate:
For satisfactory performance, concrete aggregates should be free of deleterious
materials. There are three categories of deleterious substances that may be found in
aggregates: impurities, coatings and weak or unsound particles.
3.1.2.1.8 Grading of fine and coarse aggregate:
The actual grading requirements depend on the shape and surface characteristics of
the particles. For instance, sharp angular particles with rough surfaces should have a slightly
finer grading in order to reduce the possibility of interlocking and to compensate for the high
friction between the particles
3.1.2.1.9 Maximum aggregate size:
Extending the grading of aggregate to a larger maximum size lowers the water
requirement of the mix, so that, for a specified workability and cement content, the water
/cement ratio can be lowered with a consequent increase in strength. Experimental results
indicated that above the 38.1mm maximum size the gain in strength due to the reduced water
requirement is offset by the detrimental effects of lower bond area of discontinuities
introduced by the very large particles. In structural concrete of usual proportions, there is no
advantage in using aggregate with a maximum size greater than about 25 or 40mm when
compressive strength is a criterion.
The standard type aggregate for use in pervious concrete is typically crushed stone or
river gravel. Typical sizes are from 10mm to 25mm. (Tennis et al 2004). Fine aggregates are
either used sparingly or removed altogether from the mix design. It has been shown that using
smaller aggregates increases the compressive strength of pervious concrete by providing a
tighter bond between coarse aggregate and cement. Using fine aggregates in the mix design
of pervious concrete will also decrease the void space (Tennis et al 2004). Increasing the
percent amount of larger aggregates will increase the void ratio in pervious concrete, but will
decrease the compressive strength. Using recycled aggregates has also been researched. Four
mix designs were studied using 15%, 30%, 50%, and 100% recycled aggregates and
compared to the virgin pervious concrete samples. It was found that samples containing 15%
or less recycled aggregates exhibited almost identical characteristic to the virgin sample.

24
The size of the aggregate also has an important role in pervious concrete. While a 20mm
aggregate size allows for greater void space, a 20mm aggregate improves the workability.
The use of 10mm aggregate can decrease settling and workability. Recent studies have also
found that pervious concrete with smaller aggregates had higher compressive strength. It was
noted that the smaller aggregate sizes allowed for more cementitious material to bind around
the aggregate and hence allowed for greater contact between the aggregate/binder
3.1.2.2FINE AGGREGATES:
While pervious concrete is considered a “no-fines” concrete, a small percentage of
fine particles can be added to increase the compressive strength of the pervious concrete mix.
The inclusion of fine particles has a direct correlation to the paste/mortar strength. Providing
a thicker paste layer around the coarse aggregates results in improved compressive strength
(Schaefer et al 2009). There is a significant relationship between compressive strength and
sand to gravel ratio. When the sand to gravel ratio is increased to 8 %, the mortar bulks up
and increases the strength. When the sand to gravel ratio increases beyond the 8 % mark, the
7 day compressive strength begins to fall (Schaefer et al 2009). Both Europe and Japan have
been using smaller aggregates as well as the inclusion of sand for their mix design. An
optimization of 10%-20% of fine sand to coarse aggregate has been shown to increase
compressive strength from 14 to 19 MPa. A slight decrease in permeability correlates to the
increase in fine particles.
Figure3.3: Fine aggregates

25
Figure3.4: Relationships between Fine Aggregate and Porosity/Compressive
Strength
3.1.3 WATER:
While any potable water can be used for mixing, the amount of water is critical for the
formation of the voids in pervious concrete. Water-to-cement ratios can range from 0.27 to
0.30 with ratios as high as 0.40. Careful control of water is critical. A mix design with little
water can create a very weak binder. This will create a very dry mix that is susceptible to
spalling and crumbling. A mix design with too much water can collapse the void space,
making an almost impenetrable concrete surface (NRMCA 2004).

26
As seen in Figure, the specimen in Figure (a) has too little water, the specimen in
Figure (b) has the correct amount of water, and the specimen in Figure (c) has too much
water.
(a)
(b)
(c)
Figure 3.5: Pervious Concrete With a. too little Water,
b. Appropriate Amount of Water, c. Too much Water

27
A study done by Meininger (1998) demonstrated the relationship between
compressive strength and water-to-cement ratio. The optimal w/c ratio with the highest
compressive strength was found to be between 0.3 and 0.35. Lower w/c ratios provide poor
cohesion between the aggregates. Higher w/c ratios reduce the tensile capacity by the
introduction of capillary pores.
Figure 3.6: graph showing relation between w/c ratio and compressive strength of
concrete (Meininger, 1998)
Another study by Chindaprasirt, Hatanaka, Chareerat, Mishima, and Yuasa
determined that water-to-cement ratio has a direct correlation to cement paste characteristics,
and mixing time of the porous concrete. It was noted that keeping a relatively low water-to-
cement ratio, around 0.2 to 0.3, maintains the continuity of the paste layer with coarse
aggregate. This also aids in the texture and workability of the pervious concrete. By
achieving an even thickness of the paste (150-230 mm) within the porous concrete mix, this
can achieve suitable void ratios of 15-25% and strengths ranges from 22-30 MPa.

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3.1.4 SUPPLEMENTARYCEMENTITIOUS MATERIALS (SCMS):
SCM includes fly ash, pozzolans, and slag can be added to the cement. These
influence concrete performance, setting time, rate of strength development, porosity,
permeability, etc., The key to high-performance concrete is the use of SCMs. Silica fume, fly
ash, and blast furnace slag all increase durability by decreasing permeability and cracking
 Silica fume is a by-product of silicone production. It consists of superfine spherical
particles which significantly increase the strength and durability of concrete. Used
frequently for high-rise buildings, it produces concrete that exceeds 140 MPa
compressive strength. Silica fume can replace cement in quantities of 5-12%.
 Fly ash is the waste by-product of burning coal in electrical power plants; it used to
be land filled, but now a significant amount is used in cement. This material can be
used to replace 5-65% of the Portland cement
 Blast furnace slag is the waste by-product of steel manufacturing. It imparts added
strength and durability to concrete, and can replace 20-70% of the cement in the mix.
In our project work, we have used fly ash and rice husk ash and mixture of both fly ash
and rice husk ash as the partial replacement of cement in the quantities of 10% of cement.
3.1.4.1 Fly ash:
Fly ash, also known as "pulverised fuel ash", is one of the coal combustion products,
composed of the fine particles that are driven out of the boiler with the flue gases. Ash
that falls in the bottom of the boiler is called bottom ash. In modern coal-fired power
plants, fly ash is generally captured by electrostatic precipitators or other particle
filtration equipment before the flue gases reach the chimneys. Together with bottom
ash removed from the bottom of the boiler, it is known as coal ash. Depending upon the
source and makeup of the coal being burned, the components of fly ash vary
considerably, but all fly ash includes substantial amounts of silicon dioxide (SiO2)
(both amorphous and crystalline), aluminium oxide (Al2O3) and calcium oxide (CaO), the
main mineral compounds in coal-bearing rock strata.

29
In the past, fly ash was generally released into the atmosphere, but air pollution
control standards now require that it be captured prior to release by fitting pollution
control equipment. In the US, fly ash is generally stored at coal power plants or placed in
landfills. About 43% is recycled, often used as a pozzolan to produce hydraulic
cement or hydraulic plaster and a replacement or partial replacement for Portland
cement in concrete production. Pozzolans ensure the setting of concrete and plaster and
provide concrete with more protection from wet conditions and chemical attack.
After a long regulatory process, the EPA published a final ruling in December 2014,
which establishes that coal fly ash is regulated on the federal level as "non-hazardous"
waste according to the Resource Conservation and Recovery Act (RCRA). Coal
Combustion Residuals (CCR's) are listed in the subtitle D (rather than under subtitle C
dealing for hazardous waste, which was also considered).
In the case that fly or bottom ash is not produced from coal, for example when solid
waste is used to produce electricity in an incinerator, this kind of ash may contain higher
levels of contaminants than coal ash. In that case the ash produced is often classified as
hazardous waste.
3.1.4.1.1 Chemical Composition and Classification Fly Ash:
Fly ash material solidifies while suspended in the exhaust gases and is collected
by electrostatic precipitators or filter bags. Since the particles solidify rapidly while
suspended in the exhaust gases, fly ash particles are generally spherical in shape and range in
size from 0.5 µm to 300 µm. The major consequence of the rapid cooling is that few minerals
have time to crystallize, and that mainly amorphous, quenched glass remains. Nevertheless,
some refractory phases in the pulverized coal do not melt (entirely), and remain crystalline. In
consequence, fly ash is a heterogeneous material. SiO2, Al2O3, Fe2O3 and occasionally CaO
are the main chemical components present in fly ashes. The mineralogy of fly ashes is very
diverse. The main phases encountered are a glass phase, together with quartz, mullite and the
iron oxides hematite, magnetite and/or maghemite. Other phases often identified
are cristobalite, anhydrite, freelime, periclase, calcite, sylvite, halite, portlandite, rutile and an
atase. The Ca-bearing minerals anorthite, gehlenite, akermanite and various calcium silicates
and calcium aluminates identical to those found in Portland cement can be identified in Ca-
rich fly ashes.

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Table3.2: Chemical composition of fly ash and pond ash
Compounds (%) Fly Ash Pond Ash
SiO2 38-63 37-75
Al2O3 27-44 28-53
TiO2 0.4-1.8 0-1
Fe2O3 3.3-6.4 17-34
MnO 0.1-0.5 0.1-0.6
MgO 0.01-0.5 0.1-0.8
CaO 0.2-8 0.2-0.6
K2 O 0.04-0.9 0.1-0.7
Na2O 0.07-0.43 0.05-0.31
LOI 0.2-5.0 0.01-20.0
pH 06-09 06-08
Two classes of fly ash are defined by ASTM C618: Class F fly ash and Class C fly
ash. The chief difference between these classes is the amount of calcium, silica, alumina, and
iron content in the ash. The chemical properties of the fly ash are largely influenced by the
chemical content of the coal burned (i.e., anthracite, bituminous, and lignite).
Not all fly ashes meet ASTM C618 requirements, although depending on the
application, this may not be necessary. Ash used as a cement replacement must meet strict
construction standards, but no standard environmental regulations have been established in
the United States. 75% of the ash must have a fineness of 45 µm or less, and have
a carbon content, measured by the loss on ignition (LOI), of less than 4%. In the U.S., LOI
must be under 6%. The particle size distribution of raw fly ash tends to fluctuate constantly,
due to changing performance of the coal mills and the boiler performance. This makes it
necessary that, if fly ash is used in an optimal way to replace cement in concrete production,
it must be processed using beneficiation methods like mechanical air classification.

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3.1.4.1.2 Fly Ash as Replacement of Cement:
Owing to its pozzolanic properties, fly ash is used as a replacement for Portland
cement in concrete. The use of fly ash as a pozzolanic ingredient was recognized as early as
1914, although the earliest noteworthy study of its use was in 1937. Roman structures such
as aqueducts or the Pantheon in Rome used volcanic ash or pozzolana (which possesses
similar properties to fly ash) as pozzolan in their concrete.
Use of fly ash as a partial replacement for Portland cement is particularly suitable but
not limited to Class C fly ashes. Class "F" fly ashes can have volatile effects on the entrained
air content of concrete, causing reduced resistance to freeze/thaw damage. Fly ash often
replaces up to 30% by mass of Portland cement, but can be used in higher dosages in certain
applications.
Figure3.7: Fly ash used as cement replacement
Fly ash can significantly improve the workability of concrete. Recently, techniques
have been developed to replace partial cement with high-volume fly ash (50% cement
replacement). For roller-compacted concrete (RCC) replacement values of 70% have been
achieved with processed fly ash at the Ghatghar dam project in Maharashtra, India. Due to
the spherical shape of fly ash particles, it can increase workability of cement while reducing
water demand. Proponents of fly ash claim that replacing Portland cement with fly ash
reduces the greenhouse gas "footprint" of concrete, as the production of one ton of Portland
cement generates approximately one ton of CO2, compared to no CO2 generated with fly ash.
New fly ash production, i.e., the burning of coal, produces approximately 20 to 30 tons of
CO2 per ton of fly ash.

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3.1.4.2 Rice Husk Ash:
3.1.4.2.1 Chemical Composition and Properties of Rice husk ash:
Rice husk can be burnt into ash that fulfils the physical characteristics and chemical
composition of mineral admixtures. Pozzolanic activity of rice husk ash (RHA) depends on
(i) silica content, (ii) silica crystallization phase, and (iii) size and surface area of ash
particles. In addition, ash must contain only a small amount of carbon.RHA that has
amorphous silica content and large surface area can be produced by combustion of rice husk
at controlled temperature. Suitable incinerator/furnace as well as grinding method is required
for burning and grinding rice husk in order to obtain good quality ash. Although the studies
on pozzolanic activity of RHA, its use as a supplementary cementitious material, and its
environmental and economical benefits are available in many literatures, very few of them
deal with rice husk combustion and grinding methods. The optimized RHA, by controlled
burn and/or grinding, has been used as a pozzolanic material in cement and concrete. Using it
provides several advantages, such as improved strength and durability properties, and
environmental benefits related to the disposal of waste materials and to reduced carbon
dioxide emissions. For this reason, this study investigates the strength activity index of
mortars containing residual RHA that is generated when burning rice husk pellets and RHA
as received after grinding residual RHA. The effect of partial replacement of cement with
different percentages of ground RHA on the compressive strength and durability of concrete
is examined.
Figure3.8: Rice Husk Ash

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Table3.3: Chemical Properties of R.H.A
S.No Particulars Proportion
1 Silicon Dioxide 86.94%
2 Aluminium Oxide 0.20%
3 Iron Oxide 0.10%
4 Calcium Oxide 0.3 – 2.25%
5 Magnesium Oxide 0.2 – 0.6%
6 Sodium Oxide 0.1 -0.8%
7 Potassium Oxide 2.15 – 2.30%
3.1.4.2.2 Rice Husk Ash as Cement Replacement:
Rice husk ash is used in concrete construction as an alternative of cement. The rice
paddy milling industries give the by-product rice husk. Due to the increasing rate of
environmental pollution and the consideration of sustainability factor have made the idea of
utilizing rice husk. To have a proper idea on the performance of rice husk in concrete, a
detailed study on its properties must be done.
About 100 million tons of rice paddy manufacture by-products are obtained around
the world. They have a very low bulk density of 90 to 150kg/m3. This results in a greater
value of dry volume. The rice husk itself has a very rough surface which is abrasive in nature.
These are hence resistant to natural degradation. This would result in improper disposal
problems. So, a way to use these by-products to make a new product is the best sustainable
idea. Among all industries to reuse this product, cement, and concrete manufacturing
industries are the ones who can use rice husk in a better way.
The rice husk ash has good reactivity when used as a partial substitute for cement.
These are prominent in countries where the rice production is abundant. The properly rice
husk ashes are found to be active within the cement paste. So, the use and practical
application of rice husk ash for concrete manufacturing are important. The incorporation of
rice husk ash in concrete converts it into an eco-friendly supplementary cementitious
material.

34
The following properties of the concrete are altered with the addition of rice husk
 The heat of hydration is reduced. This itself help in drying shrinkage and facilitate
durability of the concrete mix.
 The reduction in the permeability of concrete structure. This will help in penetration
of chloride ions, thus avoiding the disintegration of the concrete structure.
 There is a higher increase in the chloride and sulphate attack resistance
The rice husk ashes in the concrete react with the calcium hydroxide to bring more hydration
products. The consumption of calcium hydroxide will enable lesser reactivity of chemicals
from the external environment.
3.2 MIX DESIGN OF PERVIOUS CONCRETE
3.2.1 Void Content:
At a void content lower than 15%, there is no significant percolation through the
concrete due to insufficient interconnectivity between the voids to allow for rapid
percolation. So, concrete mixtures are typically designed for 20% void content in order to
attain sufficient strength and infiltration rate.
3.2.2 Unit Weight or Density:
The density of pervious concrete depends on the properties and proportions of the
materials used, and on the compaction procedures used in placement. In-place densities on
the order of 1600 kg/m³ to 2100 kg/m³ are common, which is in the upper range of
lightweight concretes. A pavement 125 mm thick with 20% voids will be able to store 25 mm
of a sustained rainstorm in its voids, which covers the vast majority of rainfall events in the
U.S. When placed on a 150mm thick layer of open-graded gravel or crushed rock sub base,
the storage capacity increases to as much as 75 mm of precipitation.

35
3.2.3 Water – Cement Ratio:
The water-cementitious material ratio (w/cm) is an important consideration for
obtaining desired strength and void structure in pervious concrete. A high w/cm reduces the
adhesion of the paste to the aggregate and causes the paste to flow and fill the voids even
when lightly compacted. A low w/cm will prevent good mixing and tend to cause balling in
the mixer, prevent an even distribution of cement paste, and therefore reduce the ultimate
strength and durability of the concrete. w/cm in the range of 0.26 to 0.40 provides the best
aggregate coating and paste stability. The conventional w/cm-versus-compressive strength
relationship for normal concrete does not apply to pervious concrete. Careful control of
aggregate moisture and w/cm is important to produce consistent pervious concrete.
3.2.4 Cement Content:
The total cementitious material content of a pervious concrete mixture is important for
the development of compressive strength and void structure. An insufficient cementitious
content can result in reduced paste coating of the aggregate and reduced compressive
strength. The optimum cementitious material content is strongly dependent on aggregate size
and gradation but is typically between 267 and 415 kg/m3. The above guidelines can be used
to develop trial batches. ASTM C1688 provides the tests to be conducted in the laboratory to
observe if the target void contents are attained.
Figure3.9: Arrangement of pervious concrete for pavements

36
3.2.5 Mix Design Criteria:
Pervious concrete uses the same materials as conventional concrete, except that there
is usually little or no fine aggregate. The quantity, proportions, and mixing techniques affect
many properties of pervious concrete, in particular the void structure and strength. Usually
single sized coarse aggregate up to 20 mm size normally adopted. Larger size aggregates
provide a rougher concrete finish while smaller size aggregates provide smoother surface that
may be better suited for some application such as pedestrian pathways. Although the coarse
aggregate size 6 mm to 20 mm are used, the most common being 10 mm fairly uniform size
is used. The aggregates may be rounded like gravel or angular like crushed stone
Since the pervious concrete is highly permeable, the voids between aggregate
particles cannot be entirely filled by cement paste. Use of smaller size aggregates can
increase the number of aggregate particles per unit volume of concrete. As the aggregate
particle increase the specific surface and thus increases the binding area. This results in the
improved strength of pervious concrete. However, the major thrust for using pervious
concrete stems from its capability to drain and potentially de-pollute enormous amounts of
water in short time, thus reducing the runoff rates. The physical and mechanical properties of
pervious concretes are reported elsewhere (Onstenk, 1993, Neithalath, 2004, Neithalath,
2005, Neithalath, 2006, Nelson, 1994). The use of larger size aggregates reduces clogging of
pores in the pervious concrete. The water permeation capacity or drainage properties are
closely related to the porosity with coefficient of permeability to about 0.01m/s is
recommended. A drainage rate of 100 to 270 lit/m2/min has been reported for pervious
concrete with a porosity ranging from 17% to 28% (Tennis, 2004). Recently it is suggested
that the aggregate sizes of pervious concrete should be between 9.5 mm and 19 mm and no
fine aggregate should be used.
The binder normally used in ordinary Portland cement (OPC). Pozzolanic materials
like fly ash, blast furnace slag and silica fume can also be used. However, use of pozzolanic
materials will affect setting time, strength, porosity and permeability of the resulting
concrete. Addition of fine aggregate will reduce the porosity and increase the strength of
concrete.

37
Chemical admixtures like water reducing admixture, retarders, hydration stabilizing
admixtures, viscosity modifying admixtures and internal curing admixtures are used.
Pervious concrete uses same materials as conventional concrete, except that there are usually
No or little fine aggregates. The size of the coarse aggregate used is kept fairly uniform in
size to minimize surface roughness and for a better aesthetic, however sizes can vary from
6.25 mm to 12.5 mm. Water to cement ratio should be within 0.27 to 0.34. Ordinary Portland
cement and blended cements can be used in pervious concrete. Water reducing admixtures
and retarders can be used in pervious concrete.
General issues encountered compared to standards concrete are
1. Long mixing time in the batching plants (about 20 minutes)
2. Poor workability, very dry mix, difficult for placing
3. Amount of water used in mix is important as same as standards concrete
4. If too much water used, segregate is expected, usually higher than standards concrete
5. If too little water is used, not easy to mix, balling of mix in the mixer.
Table3.4: Typical mix design of pervious concrete as suggested by ACI 522 R-10
Materials Proportions (Kg/m3)
Cement (OPC or blended) 270 to 415
Aggregate 1190 to 1480
Water: cement ratio (by mass) 0.27 to 0.34
Fine: coarse aggregate ratio (by mass) 0 to 1:1
Chemical admixtures (retarders) are commonly used and Addition of fine aggregates will decrease
the void content and increase strength

38
Figure3.10: preparation of pervious concrete cubes
3.2.6 NRMCA procedure for Pervious Concrete Mixture Proportioning:
The following mixture proportioning approach can be used to quickly arrive at pervious
concrete mixture proportions that would help attain void content of freshly mixed pervious
concrete when measured in accordance with ASTM C1688 similar to the target value.
(1) Determine the dry-rodded unit weight of the aggregate and calculate the void content.
Estimate the approximate percentage and volume of paste needed. The paste volume
(PV) is then estimated as follows:
Vp (%) = Aggregate Void Content (%) + CI (%) - Vvoid (%)
Where, CI = compaction index and
Vvoid = design void content of the pervious concrete mix.

39
The value of CI can be varied based on the anticipated consolidation to be used in the
field. For greater consolidation effort a compaction index value of 1 to 2% may be
more reasonable. For lighter level of consolidation a value of 7 to 8% can be used.
NRMCA used a value of 5% to get similar values between measured fresh pervious
concrete void content (ASTM C1688) and design void content. Using a smaller value
for CI (%) will reduce the paste volume.
(2) Calculate the paste volume, Vp in ft3 per cubic yard of pervious concrete:
Vp, ft3 = Vp (%) × 27
(3) Select the w/c ratio for the paste. Recommended values are in the range of 0.25 to
0.36.
(4) Calculate the absolute volume of cement
vc,ft3
= vp/[1+(w/c*RDc)]
Where: RDc is the specific gravity of cement (typically 3.15)
(5) Calculate the volume of water, Vw
Vw, ft3 = Vp – Vc
(6) Calculate the volume of SSD aggregate (Vagg)
Vagg = 27 – (Vp +Vvoid)
Where: Vvoid is the design void content for the pervious concrete mix.
Convert the volumes to weights of ingredients per cubic yard and for trial batches:
Cement (lb/yd3) = Vc × RDc × 62.4
Water (lb/yd3) = Vw × 62.4
SSD Coarse Aggregate (lb/yd3) = Vagg × RDagg × 62.4
Trial batches are prepared to evaluate mix characteristics of the pervious concrete
mixture. Make appropriate adjustments are made to account for aggregate moisture content.
If paste is high, pick a lower value or change CI (%). Avoid excessive cementitious content
should be avoided. The consistency of the paste can be evaluated separately to ensure that it
is not too dry or causes paste run down by being too wet. The density of the mixture should
be measured in accordance with ASTM C1688 from which the void content is calculated to
ensure that values are in line with the design void content. Then evaluate mixture for
consistency, specification requirements and placement method used by the pervious concrete
contractor.

40
NRMCA has developed a pervious concrete mixture proportioning guideline and
spreadsheet software that will develop trial batch mixture proportions using volumetric
considerations and make the necessary calculations for production batches when mixture
proportions are finalized after trial batch evaluations.
3.3 COMPRESSIVE STRENGTHAND PERMEABILITYOF PERVIOUS
CONCRETE
3.3.1 Compressive Strength of Normal Concrete:
Out of many test applied to the concrete, this is the utmost important which gives an
idea about all the characteristics of concrete. By this single test one judge that whether
Concreting has been done properly or not. Compressive strength of concrete depends on
many factors such as water-cement ratio, cement strength, quality of concrete material,
Quality control during production of concrete etc., Test for compressive strength is carried
out either on cube or cylinder. Various standard codes recommend concrete cylinder or
concrete cube as the standard specimen for the test.
For cube test two types of specimens either cubes of 150 mm X 150 mm X 15 mm or
100 mm X 100 mm x 100 mm depending upon the size of aggregate are used. For most of the
works cubical moulds of size 150 mm x 150 mm x 150 mm are commonly used.
This concrete is poured in the mould and tempered properly so as not to have any
voids. After 24 hours these moulds are removed and test specimens are put in water for
curing. The top surface of these specimen should be made even and smooth. This is done by
putting cement paste and spreading smoothly on whole area of specimen.

41
Figure3.11: Standard compressive strength cube mould
These specimens are tested by compression testing machine after 7 days curing or 28
days curing. Load should be applied gradually at the rate of 140 kg/cm2 per minute till the
Specimens fails. Load at the failure divided by area of specimen gives the compressive
strength of concrete.
3.3.1.1 Preparation of Cube Specimens
The proportion and material for making these test specimens are from the same
concrete used in the field.
3.3.1.2 Mixing
Mix the concrete either by hand or in a laboratory batch mixer
Figure3.12: mixing of pervious concrete

42
3.3.1.3 Hand Mixing:
(i)Mix the cement and fine aggregate on a water tight none-absorbent platform until the
mixture is thoroughly blended and is of uniform colour
(ii)Add the coarse aggregate and mix with cement and fine aggregate until the coarse
aggregate is uniformly distributed throughout the batch
(iii)Add water and mix it until the concrete appears to be homogeneous and of the desired
consistency
3.3.1.4 Sampling
(i) Clean the mounds and apply grease.
(ii) Fill the concrete in the moulds in 3 equal layers
(iii) Compact each layer with not less than 35strokes per layer using a tamping rod (steel bar
16mm diameter and 60cm long, bullet pointed at lower end)
(iv) Level the top surface and smoothen it with a trowel
Figure3.13: compaction of pervious concrete with tamping rod

43
3.3.1.5 Curing
The test specimens are stored in moist air for 24hours and after this period the
specimens are marked and removed from the moulds and kept submerged in clear fresh water
until taken out prior to test.
3.3.1.6 Procedure:
(I) Remove the specimen from water after specified curing time and wipe out excess water
from the surface.
(II) Take the dimension of the specimen to the nearest 0.2m
(III) Clean the bearing surface of the testing machine
(IV) Place the specimen in the machine in such a manner that the load shall be applied to the
opposite sides of the cube cast.
(V) Align the specimen centrally on the base plate of the machine.
(VI) Rotate the movable portion gently by hand so that it touches the top surface of the
specimen.
(VII) Apply the load gradually without shock and continuously at the rate of
140kg/cm2/minute till the specimen fails
(VIII) Record the maximum load and note any unusual features in the type of failure.
3.3.1.7 NOTE:
Minimum three specimens should be tested at each selected age. If strength of any
specimen varies by more than 15 per cent of average strength, results of such specimen
should be rejected. Average of these specimens gives the crushing or compressive strength of
concrete. The strength of concrete increases with increase in age. The following table shows
the strength of concrete at different ages in comparison with the strength at 28 days after
casting.

44
Table3.5: Compressive strength of concrete at various ages
Age Strength per cent
1 day 16%
3 days 40%
7 days 65%
14 days 90%
28 days 99%
Table3.6: Compressive strength of different grades of concrete at 7 and 28 days
Grade of
Concrete
Minimum compressive strength
N/mm2 at 7 days
Specified characteristic compressive
strength (N/mm2) at 28 days
M15 10 15
M20 13.5 20
M25 17 25
M30 20 30
M35 23.5 35
M40 27 40
M45 30 45
3.3.2 COMPRESSIVE STRENGTH OF PERVIOUS CONCRETE:
In the laboratory, pervious concrete mixtures have been found to develop compressive
strengths in the range of 3.5 MPa to 28 MPa, which is suitable for a wide range of
applications. Typical values are about 17 MPa. As with any concrete, the properties and
combinations of specific materials, as well as placement techniques and environmental
conditions, will dictate the actual in-place strength. However, currently there is no ASTM test
standard for compressive strength of pervious concrete.

45
Testing variability measured with various draft test methods has been found to be
high and therefore compressive strength is not recommended as an acceptance
criterion. Rather, it is recommended that a target void content (between 15% to 25%) as
measured by ASTM C 1688: Standard Test Method for Density and Void Content of Freshly
Mixed Pervious Concrete be specified for quality assurance and acceptance.
Figure3.14: cubes tested for compressive strength
3.3.3 DENSITY AND POROSITY:
Figure3.15: Typical cross section of pervious concrete for pavement.
The density of pervious concrete depends on the properties and proportions of the
materials used, and on the compaction procedures used in placement. In-place densities on
the order of 1600 kg/m³ to 2100 kg/m³ are common, which is in the upper range of
lightweight concretes. A pavement 125 mm thick with 20% voids will be able to store 25 mm
of a sustained rainstorm in its voids, which covers the vast majority of rainfall events in the
U.S.

46
3.3.4 PERMEABILITY OF PERVIOUS CONCRETE:
The permeability of pervious concrete was determined using a falling head
permeability set up Figure 8. Water was allowed to flow through the sample, through a
connected standpipe which provides the water head. Before starting the flow measurement,
the samples were wrapped with polythene inside the cylinder. Then the test started by
allowing water to flow through the sample until the water in the standpipe reached a given
lower level. A constant time of 5seconds was taken for the water to fall from one head to
another in the standpipe. The standpipe was refilled and the test was repeated when water
reached a lower. The permeability of the pervious concrete sample was evaluated from the
expression given below:
Figure3.16: variable head permeability test apparatus

47
Formula: K=2.303 aL/A (t2-t1) log (h1/h2)
Where,
a = the sample cross section area
A = the cross section of the standpipe of diameter (d) = 0.95cm2
L = the height of the pervious concrete
(t2 - t1) = change in time for water to fall from one level to another (5secs.)
h1= upper water level
h2= Lower water level
D= diameter of sample (10.5cm)
d= diameter of standpipe (1.1cm)
Theoretically, the coefficient of permeability generally in the order of 1mm/sec for a
void ratio of 20% and the rate of flow is in the range of 120 litres/min/m2 to 200 litres/min/m2
In general, the concrete permeability limitation is not a critical design criterion.
Consider a passive pervious concrete pavement system overlying a well-draining soil.
Designers should ensure that permeability is sufficient to accommodate all rain falling on the
surface of the pervious concrete. For example, with a permeability of 140 L/m2/min, a rainfall
in excess of 0.24 cm/s would be required before permeability becomes a limiting factor. The
permeability of pervious concretes is not a practical controlling factor in design. However,
the flow rate through the sub grade may be more restrictive.

48
3.3.5 Storage Capacity:
Storage capacity of a pervious concrete system typically is designed for specific
rainfall events, which are dictated by local requirements. The total volume of rain is
important, but the infiltration rate of the soil also must be considered. The total storage
capacity of the pervious concrete system includes the capacity of the pervious concrete
pavement, the capacity of any sub base used, and the amount of water which leaves the
system by infiltration into the underlying soil. The theoretical storage capacity of the pervious
concrete is its effective porosity: that portion of the pervious concrete which can be filled
with rain in service. If the pervious concrete has 15% effective porosity, then every 25 mm of
pavement depth can hold 4 mm of rain. For example, a 100mm thick pavement with 15%
effective porosity on top of impervious clay could hold up to 15 mm of rain before
contributing to excess rainfall runoff. Another important source of storage is the sub base. A
conventional aggregate sub base, with higher fines content, will have a lower porosity (about
20%). From the example above, if 100 mm of pervious concrete with 15% porosity was
placed on 150 mm of clean stone, the nominal storage capacity would be 75 mm of rain. The
effect of the sub base on the storage capacity of the pervious concrete pavement system can
be significant.
A critical assumption in this calculation is that the entire system is level. If the top of
the slab is not level, and the infiltration rate of the sub grade has been exceeded, higher
portions of the slab will not fill and additional rainfall may run to the lowest part of the slab.
Once it is filled, the rain will run out of the pavement, limiting the beneficial effects of the
pervious concrete. These losses in useable volume because of slopes can be significant, and
indicate the sensitivity of the design to slope. Pipes extending from the trenches carry water
travelling down the paved slope out to the adjacent hillside. The high flow rates that can
result from water flowing down slope also may wash out sub grade materials, weakening the
pavement.

49
3.4 Improvement of Strength of Pervious Concrete:
 As the strength of pervious concrete is less when compared to conventional concrete,
its applications are limited to great extent
 The main aim of our project is to improve the strength of pervious concrete so that it
can be used for large number of applications
 The strength improvement can be done by
(1) Addition of small quantity of fine aggregates
(2) Addition of small quantities of cementitious materials
(3) Usage of small sized coarse aggregates
(4) Using low w/c ratio etc.,
 Among the above methods, we have selected addition of small quantity of fine
aggregates, addition of cementitious materials such as fly ash, rice husk ash and
mixture of both fly ash and rice husk ash.
 The compressive strength of pervious concrete inversely proportional to permeability.
As the compressive strength increases, the permeability will be decreased and vice-
versa.
 The main purpose of pervious concrete is permeability. By improving the strength we
should not forget the effect of permeability.
 In our project work, we have considered both the aspects. We tried to improve the
compressive strength of pervious concrete without compromising the permeability
much.
 Theoretically, it is stated that the strength characteristics will be increased if the fine
aggregates are added 5-10% quantity of coarse aggregates.

50
Chapter-4
RESULTS AND DISCUSSIONS
4.1 Optimised Mix Design of Pervious Concrete (With 20mm Aggregates, No Sand),
Tested At NEC Nellore concrete technology laboratory:
Properties of materials tested in the laboratory:
4.1.1 Tests on cement:
OPC-53 grade cement:
Table4.1: properties of cement tested at Concrete technology laboratory
S.No Property Value
1 Specific gravity 3.15
2 Bulk density 1120 kg/m3
3 Fineness 225 m2/kg
4 Initial setting time 35 min
5 Final setting time 132 min
6 Consistency 28%
4.1.2 Tests on coarse aggregates:
Coarse aggregates (locally available 20mm size aggregates):
Table4.2: properties of coarse aggregates tested at Concrete technology laboratory
S.No Property Value
1 Bulk density 1583.34 kg/m3
2 Impact strength 26.4%
3 Crushing strength 25.45%
4 Void content 37.16%

51
4.1.3 Tests on fine aggregates:
Fine aggregates (locally available):
Table4.3: properties of fine aggregates tested at Concrete technology laboratory
S.No Property Value
2 Fineness modulus 2.5
3 Dry rodded unit weight 1720 kg/m3
4 Water absorption 0.6%
4.1.4 Optimised mix proportions:
Optimised mix proportion is calculated with 20mm coarse aggregate as standard pervious
concrete:
 The void ratio and unit weight are the important factors to be considered in mix
design process
 According to mix design, the quantity of cement calculated for one cubic meter of
pervious concrete is 390 kgs based on NRMCA, USA
 The other important considerations are aggregate to cement (A/C) ratio and water to
cement (W/C) ratio. We can consider different types of aggregates to cement ratios
and water to cement ratios as per our requirement.
 The mix design procedure gave the value of cement to aggregate ratio as 1:4.25 or
approximately 1:4 for the size of aggregates passing through 20mm and retained on
10mm IS sieve
 The W/C ratio for the pervious concrete should be in the range of 0.25 to 0.36. For the
proper workability we have selected the W/C ratio as 0.3 and it is fixed after doing
samples with water to cement ratios o 0.25, 0.30 and 0.35.
 The design void ratio of pervious concrete is 20% and the unit weight ranges from
1600 to 2100 kg/m3

52
 The quantities of Materials as per mix design
Cement = 390 kg/m3
Coarse aggregates = 1669.2 kg/m3
Water = 117 liters
Table4.4: optimised mix proportions
Materials Proportions (Kg/m3)
Cement (OPC-53 grade) 390
Aggregate (20mm) 1669.2
Water: cement ratio (by mass) 0.3
Fine aggregates 0
 The cement we used in our project work is Ordinary Portland Cement of 53 grade
 The size of coarse aggregates is passing 20 mm and retained on 10 mm IS sieve
 The water used is available in the laboratory.
4.2 Compressive strength of Standard Pervious Concrete with 0% Fines:
Quantities of materials:
Cement = 390 kg/m3
Fine aggregates = 0 kg/m3
Water = 117 litres per CUM
The following table provides the information of compressive strength of standard
pervious concrete with 0% fine aggregates tested for 7,14 and 28 days in compression testing
machine, permeability tested in variable head permeability test after 28 days and also unit
weight of concrete after 24 hours from preparation of concrete.

53
4.2(a) COMPRESSIVE STRENGTH:
Table4.5: compressive strength and unit weight of standard pervious concrete (0%fines)
S.No
Age of concrete
(days)
Compressive Strength Of Standard
Pervious Concrete (MPa)
Unit Weight After 24
Hours(Kg/m3)
1 7 16.72
2112.202 14 19.26
3 28 21.06
4.2(b) Compressive strength comparison between Normal concrete and Pervious concrete:
Table4.6: Comparison of strength between normal concrete and pervious concrete
S.NO
Age of concrete
(days)
Normal Concrete of M20 (MPa) Pervious Concrete(MPa)
1 7 18.53 16.72
2 14 25.67 19.26
3 28 28.20 21.06
Figure4.1: Graph of showing relation between compressive strength of normal and
pervious concrete
The compressive strength of pervious concrete is less than the normal concrete due to
the absence of fine aggregates or presence of voids. It should be noted that the normal
concrete is completely impermeable in nature.
0
5
10
15
20
25
30
normal concrete 0%fines pervious concrete
CompressivestrengthinMPa
Types of concrete
compressive strength comparison
7days
14 days
28 days

54
4.3 Compressive strength of pervious concrete with the addition of fine aggregates
4.3.1 Addition of 5% Fines in Total Coarse Aggregate Quantity
Cement : Fine aggregates : Coarse aggregates : Water
390 kgs : 83 kgs : 1577 kgs : 117 litres
All the materials are calculated for 1 CUM
Table4.7: compressive strength and unit weight of pervious concrete with 5% fines
S.No
Age Of
Concrete
(days)
Compressive
strength of
pervious concrete
with 0%
fines(MPa)
Compressive
Strength Of
Pervious Concrete
With 5% Fines
(MPa)
Hours(Kg/m3
)
1 7 16.72 17.36
2065.302 14 19.26 19.60
3 28 21.06 21.65
Figure 4.2: graph of Age of concrete Vs compressive strength of 5% fines pervious
concrete
From the above table and graph, the 7, 14 and 28 days compressive strength of 5%
fines pervious concrete is high. The unit weight of 5% fines pervious concrete is less due to
less weight fine particles in the place of coarse aggregates.
0
5
10
15
20
25
0% fines 5% fines
compressivestrengthinMpa
pervious concrete with 0 and 5% fines in %
compressive strength comparisons
7 days
14 days
28 days

55
4.3.2 Addition of 6% Fines in Total Coarse Aggregate Quantity
Cement = 390 kg/m3
Fine aggregates = 99.6 kg/m3 (6% of coarse aggregates)
S.No
Age
of
concrete
(days)
Compressive strength
of pervious concrete
with 0% fines
(MPa)
Compressive Strength Of
Pervious Concrete With
6% Fines (MPa)
Unit Weight
After 24
Hours(Kg/m3)
1 7
16.72
17.75
2040.502 14
19.26
19.73
3 28
21.06
22.47
Figure 4.3: Graph of age of concrete Vs compressive strength h of 6% fines pervious
concrete
0
5
10
15
20
25
0% fines 6% fines
7 days
28 days
14 days

56
4.3.3 Addition Of 7% Fines in Total Coarse Aggregate Quantity
Cement = 390 kg/m3
S.No
Age Of
Concrete
(days)
Compressive Strength
Of Pervious Concrete
with 0% fines
(MPa)
With 7% Fines (MPa)
Hours(Kg/m3)
1 7 16.72 18.32
2025.872 14 19.26 19.93
3 28 21.06 23.79
Figure 4.4: Graph of Age of concrete Vs compressive strength of 7% fines pervious
concrete
0
5
10
15
20
25
o%fines 7%fines
compresssivestrengthinMPa
Pervious concretewith 0 and 7% fines in %
Compressive strength comparison
7days
14 days
28 days

57
Cement = 390 kg/m3
S.No
Age
Of Concrete
(days)
Compressive
Strength Of Pervious
Concrete with 0%
Fines (MPa)
Compressive
Concrete With 8%
Fines (MPa)
Unit Weight
After 24
Hours(Kg/m3)
1 7
16.72
18.98
1996.652 14
19.26
21.47
3 28
21.06
24.13
concrete
0
5
10
15
20
25
30
0%fines 8%fines
compressivestrength comparison
7 days
14 days
28 days

58
Cement = 390 kg/m3
S.NO
Age
of
concrete
(days)
Compressive
Strength Of
Pervious Concrete
with 0% Fines
(MPa)
With 9% Fines (MPa)
Unit Weight After
24 Hours(Kg/m3)
1 7
16.72
18.76
1986.26
2 14
19.26
21.23
3 28
21.06
23.47
concrete
0
5
10
15
20
25
0%fines 9%fines
7 days
14 days
28 days

59
Cement = 390 kg/m3
Coarse aggregates = 1494 kg/m3
Fine aggregates = 166 kg/m3 (10% of coarse aggregates)
S.NO
Age
of
concrete
(days)
Compressive
Strength Of
Pervious Concrete
with 0% Fines
(MPa)
Compressive
Concrete With 10%
Fines(MPa)
Unit Weight After
24 Hours(Kg/m3)
1 7 16.72 18.28
1986.26
2 14 19.26 20.23
3 28 21.06 22.87
Figure4.7: Graph of Age of concrete Vs compressive strength of 10% fines pervious
concrete
0
5
10
15
20
25
0%fines 10%fines
7 days
14 days
28 days

60
4.4 compressive strength of pervious concrete with the replacement of
cementitious materials:
We have tested 3 types of mixes. In the first mix, the fly ash is replaced by 10% of
cement. In second mix, Rice Husk Ash is replaced by 10% of cement. In the third mix,
mixture of both fly ash (5%) and Rice Husk Ash (5%) is replaced by 10% of cement.
4.4.1 Replacement of Fly ash by 10% of Cement
Cement : Fly Ash : Coarse Aggregates : Water
351 kgs : 39 kgs : 1510.60 kgs : 117 litres
All the materials are calculated for 1 CUM
Table4.13: compressive strength and unit weight of pervious concrete with 10% fly ash
S.No
Age Of
Concrete
(days)
Compressive
Strength Of
standard
Pervious
Concrete(MPa)
Compressive
Concrete 10%
Flyash(MPa)
Unit Weight After
24 Hours(Kg/M3)
1 7 16.72 17.26
1941.922 14 19.26 19.92
3 28 21.06 22.87
Figure4.8: Graph of Age of concrete Vs compressive strength of 10% fly ash
replacement
0
5
10
15
20
25
0%fines 10%flyash
pervious concrete with 0 and 10% fly ash replacement
7 days
14 days
28days

61
4.4.2 Replacement of Rice Husk Ash By 10% of Cement
Cement = 351 kg/m3
Rice husk ash = 39 kg/m3
Table4.14: compressive strength and unit weight of pervious concrete with 10% Rice
husk ash
S.No
Age of
Concrete
(days)
Compressive
Strength Of
standard Pervious
Concrete (MPa)
10% Rice Husk
Ash(MPa)
Unit Weight
After 24
Hours(Kg/m3)
1 7
16.72
18.47
1960.602 14
19.26
21.13
3 28
21.06
23.93
Figure4.9: Graph of Age of concrete Vs compressive strength of 10% rice husk ash
replacement
0
5
10
15
20
25
0%fines 10%Rice husk ash
pervious concrete with 0 and 10% Rice husk ash replacement
7 days
14 days
28days

62
4.4.3 Replacement of Both Fly Ash (5%) And Rice Husk Ash (5%) by 10% of Cement
Cement : Coarse aggregates : Water
351 kgs : 1510.60 kgs : 117 litres
Fly ash = 19.5 kg/m3
Rice husk ash = 19.5 kg/m3
All the materials are calculated per CUM
Table4.15: compressive strength and unit weight of pervious concrete with 10% fly ash
and Rice husk ash
S.No
Age
of Concrete
(days)
Compressive
Strength of
Standard Pervious
Concrete (MPa)
Compressive Strength of
Pervious Concrete 10%
Rice Husk Ash(MPa)
Unit Weight After
24 Hours(Kg/m3)
1 7 16.72 16.79
1952.852 14 19.26 20.33
3 28 21.06 23.12
Figure4.10: Graph of Age of concrete Vs compressive strength of 5% fly ash and 5%
Rice husk ash replacement
From the above three mixes, the cement replacement by mixture of fly ash and rice
husk ash gives least values of compressive strength. This may due to different properties of
fly ash and rice husk ash may not be homogeneous.
0
5
10
15
20
25
0% fines 5% fly ash and 5% RHA
pervious concrete with 0 and 5% fly ash and 5% rice husk ash replacement
compressivestrength comparison
7 days
28 days
14 days

63
4.5 PERMEABILITY:
The permeability is the property to allow the water to flow through it. Generally, the
permeability is determined either by constant head permeability test or by variable head
permeability test. In our project work, we have taken variable head permeability test as it
suits best for the pervious concrete.
To determine the permeability of pervious concrete, we have prepared a beam of size
400*400*60mm. The permeability test is conducted for the standard pervious concrete (0%
fines), pervious concrete with 8% fine aggregates, pervious concrete with 10% fine
aggregates, pervious concrete with 10% fly ash as cement replacement and pervious concrete
with 10% rice husk ash as cement replacement tested after 28 days from preparation.
4.5.1 Permeability of Standard pervious concrete with 0% fine aggregates
Cement = 390 kg/m3
Table 4.16: unit weight and coefficient of permeability of standard pervious concrete
with 0% fines
S.No
Unit weight of standard pervious concrete
(0% fines) after 24 hours (kg/m3)
Coefficient of permeability
K (cm/sec)
1 2118.84 1.02

64
4.5.2 Permeability of Pervious concrete with 8% fine aggregates
Cement = 390 kg/m3
Fine aggregates = 132.80 kg/m3
Table4.17: unit weight and coefficient of permeability of standard pervious concrete
with 8% fines
S.No
K (cm/sec)
1 1998.78 0.76
4.5.3 Permeability of Pervious concrete with 10% fine aggregates
Cement = 390 kg/m3
with 10% fines
S.No
Unit weight of standard pervious
concrete (0% fines) after 24 hours
(kg/m3)
K (cm/sec)
1 1949.76 0.49

65
4.5.4 Pervious concrete with 10% fly ash as cement replacement
Cement = 351 kg/m3
Fly ash = 39 kg/m3
with 10% Fly ash as cement replacement
S.No
K (cm/sec)
1 1949.76 0.59
4.5.5 Permeability of Pervious concrete with 10% Rice husk ash as cement replacement
Cement = 351 kg/m3
Rice husk ash = 39 kg/m3
with 10% rice husk ash as cement replacement
S.No
K (cm/sec)
1 1949.76 0.53

66
4.6 COMPARISONS:
4.6.1 Compressive Strength Comparisons:
4.6.1.1 Compressive Strength Comparison of Standard Pervious Concrete and Pervious
Concrete with Fine Aggregates:
Table4.21: compressive strength of pervious concrete with different quantities of fine
aggregate
S.No
Age of
concrete
Standard
pervious
concrete(0%
fines), MPa
Pervious
concrete
with 5%
fines,
MPa
Pervious
concrete
with 6%
fines,
MPa
Pervious
concrete
with 7%
fines,
MPa
Pervious
concrete
with 8%
fines,
MPa
Pervious
concrete
with 9%
fines,
MPa
Pervious
concrete
with
10%
fines,
MPa
1 7 16.72 17.36 17.75 18.32 18.98 18.76 18.28
2 14 19.26 19.60 19.73 19.93 21.47 21.23 20.23
3 28 21.06 21.98 22.47 23.79 24.13 23.47 22.87
The above table clearly shows that the compressive strength of pervious concrete
increases with increase in age and percentage of fines up to 8%. Beyond this value, the
compressive strength starts to decrease.
A graph showing the variation in compressive strength of pervious concrete by using
the above values by taking percentage fines on x-axis and compressive strength on y-axis for
7,14 and 28 days as shown below.

67
Figure4.11: Graph of compressive strength of pervious concrete with different
quantities of fine aggregates
 The 7 days compressive strength of 5% fines pervious concrete is less than the
standard pervious concrete with 0% fine aggregates. It may be due slow development
of early strength due to mixing
 The pervious concrete with 8% fine aggregates gives highest compressive strength
beyond which the compressive strength begins to fall.
0
5
10
15
20
25
30
0 5 6 7 8 9 10
CompressivestrengthinMpa
Percentage of fines(%)
Comparisonof compressive strengthwith different fine
aggregatequantities
7 days
14 days
28 days

68
4.6.1.2 Compressive Strength Comparison of Standard Pervious Concrete and
Pervious Concrete with cement replacement:
Table 4.22: compressive strength of pervious concrete with cement replacement
S.No Days
Standard
pervious
concrete with
0% fines, MPa
Pervious
concrete with
10% FA as
cement
replacement,
MPa
Pervious
concrete with
10% RHA as
cement
replacement,
MPa
Pervious
concrete with
10% FA and
RHA as,
MPa
1 7 16.72 17.26 19.92 17.79
2 14 19.26 19.92 21.13 20.33
3 28 21.06 22.87 23.93 23.12
FA = Fly Ash
RHA = Rice Husk Ash
Figure 4.12: Graph of Age of concrete Vs compressive strength value comparisons with
the cementitious materials
 The pervious concrete with 10% Rice husk ash as cement replacement gives highest
value of compressive strength when compared to fly ash replacement and standard
pervious concrete.
 The pervious concrete with mixture of fly ash and rice husk ash given least value of
compressive strength. This may due to non homogeneity between the two
cementitious materials.
0
5
10
15
20
25
30
0% Fines 10% Flyash 10% RHA 5% Flyash and
5% RHA
Compressivestrength(Mpa)
Pervious concrete with different quantities of CMs
Compressivestrength comparison
7 days
14 days
28 days

69
4.6.2 Permeability Comparisons:
4.6.2.1 Comparison of Permeability of Standard Pervious Concrete and
Pervious Concrete with Little Amounts of Fine Aggregates:
Table 4.23: Co-efficient of permeability of pervious concrete with addition of different
quantities of fine aggregates and cementitious materials
S.No
Standard
pervious
concrete with
0% fines
(cm/sec)
Pervious
concrete with
8% fine
aggregates
(cm/sec)
Pervious
concrete with
10% fine
aggregates
(cm/sec)
Pervious
concrete with
10% fly ash as
cement
replacement
(cm/sec)
Pervious
concrete with
10% rice
husk ash as
cement
replacement
(cm/sec)
1. 1.02 0.76 0.49 0.59 0.53
Figure 4.13: Graph of co-efficient of permeability of pervious concrete with addition of
different quantities of fine aggregates and cementitious materials
 The co-efficient of permeability is maximum of 1.02 cm/sec for standard pervious
concrete with 0% fine aggregates and minimum of 0.49 cm/sec for pervious concrete
with 10% fine aggregates
 The pervious concrete with 10% fly ash has minimum co-efficient of permeability of
0.59 cm/sec and that of rice husk ash is 0.53 cm/sec. The reason for least values of
permeability is due to fineness of cementitious materials.
0
0.2
0.4
0.6
0.8
1
1.2
0 fines 8 10 10% Flyash 10% RHA
Coefficientof
permeability(K)cm/sec)
Pervious concrete with different quantities of fines and CMs(%)
Co-efficient of permeability
coefficient of permeability

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