This document discusses concrete absorption and permeability. It provides information on: 1) Concrete absorption values, which should not exceed 7% for good dense concrete. Very good concrete has an absorption of 5-6%, while typical commercial concrete is 6-7% and pretty ordinary concrete is 7-10%. 2) Permeability depends on factors like water-cement ratio, concrete age, and degree of hydration. Generally, higher strength cement paste is more durable and less permeable. 3) Permeability relates to pore size, distribution, and continuity, while absorption has no connection to permeability and depends on water-cement ratio. 4) Proper curing is important to achieve

1. One time floor treatment for the life of your concrete floor

2. The process of penetration of a liquid Chemical into substrate with resulting
makes it part of itself and also increases substrate weight.
% Absorption= (Wet weight- Dry weight) X100/Dry Weight
Some water absorption Value given Value
(1) Granite-------------0.3%/ (2) Lime Stone-------0.9%
(3) Sand Stone------1.8% (4) Fine sand-------- 2.3 %
(4) Course sand---- 2.0 %
Absorption of Products
Continued…

3. The average absorption of test sample shall not be greater than 7% for good dense
concrete.
Concrete water absorption value as per quality
(1) Very good Concrete ---5-6%
(2) Typical Commercial concrete—6-7%
(3) Pretty Ordinary Concrete—7-10%

5. Permeability of Concrete
The permeability of concrete is controlled by capillary pores. The
permeability depends mostly on W/C Ratio, age of Concrete, degree of
hydration.
In general the higher the strength of cement paste, the higher the durability
& the lower is the permeability.

6. Difference in Permeability and Absorption
Permeability relates to size of pores, their distribution and most importantly their
continuity.
Permeability has no connection with absorption. It is related with W/C ratio of
concrete.

7. The larger pore ranging from 10 μm -50nm are the unfilled residual spaces
between cement grain known as capillary pores.
The finest pore ranging 10- 0.5 nm are called gel pores or internal C-S-H
gel porosity.
The Pore System and it’s Classification
Continued…

8. Continued…

9. Void greater than 10 μm often exist in the concrete either from
unintentional entrapment of air during mixing procedure or from
intentional entrapment of air which purposefully disperses air voids
approximately 50 nm in diameter through out the paste.
Size of capillary and gel pores overlap and thus make continuous
spectrum of pore size in cement paste.
0.5 nm or smaller are formed by the interlayer spaces of C-S-H jell.
Continued…

10. Type of
pore
Description Size water technique Properties
Capillary pores Large 10 μm-50 nm Evaporable
Bulk water
SEM, OM Permeability,
Strength
Capillary pores Medium 50-10 nm Evaporable SEM, Permeability,
Strength
Gel Pores small 10-2.5 nm Evaporable Absorption Permeability,
Strength, Shrinkage
(High RH)
Gel Pores Micro Pores 2.5- 0.5 nm Non Evaporable
Intermolecular
interactions
Absorption/IS Shrinkage, Creep
(35-11 % RH)
Interlayer
Spaces
Structural <0.5 nm Non Evaporable Absoption/Thermal Shrinkage and Creep
(<11 % RH)
ITZ 20-50 20 μm-50 nm Bulk Water SEM/OM Permeability,
Strength
SEM- Scanning Electron Microscopy
OM-Optical Microscopy
IS-Impedence Spectroscopy

11. Basic Ph. of concrete ranges from 12 to 13. At exposed surfaces due to
carbonation it falls soon, and overtime fronts of carbonated concrete ph
falls below 8.5.
Surface between ph-9-11 can withstand salting in winter and variable
weather condition.
Concrete Ph. Factor:
The ph. value between 7 to 9 starts breakdown and may exhibit sign of early
damage.
When ph. falls from below 6.5 then it damage due to very light movement of
footfall and when it falls below 6 the critical damage situation and it will show
aggregate.

12. Calcium Hydroxide (CH)
 Calcium Hydroxide, also known by its mineral name portlandite, form
from C3S (Calcium tri silicate) and to lesser extent, C2S (Calcium die
silicate) via reaction when it comes in contact with water.
 Calcium Hydroxide forms as crystals with wide range of shapes and
sizes, depending primarily on the amount of room available for
growth. Crystals that nucleate in the capillary pores tend to form
irregular hexagonal plate shaped crystals several micron across, large
enough to be seen in the optical microscope.
Continued…

13.  CH is most soluble of the hydration products and thus is a weak link in
cement and concrete form a durability point of view. If the paste is exposed
to fresh water, the CH will leach out, increasing porosity and thus making
the paste more vulnerable to further leaching and chemical attack.
 Calcium hydroxide contributes slightly to the strength and
impermeability of the paste because it reduces the total pore volume by
converting some of the liquid water into solid form
 It occupies about 15% of the volume of normal Portland cement paste.

14. CURING: Concrete needs to stay moist in order for it cure but some sealer
need the concrete to be dry for them to cure and stick properly. Temperature
and humidity levels play major role in whether your concrete or sealer cures
properly.
Understanding how curing, temperature, dew point and humidity levels
work together will shed light on how you can manage drying.
Temperature and Relative Humidity

15. It is well known in hot conditions things dry out fast so during the summer
month it is vital to make sure bare exposed concrete that is still stays moist.
On the other hand in cold temperatures make it harder to dry things out .
cold concrete takes much longer to dry out because water does not
evaporate as fast.
Temperature effect on Curing Process

16. Drying is also known as evaporation. The rate at which water evaporates
depends upon several factors, including the temperature, relative humidity and
air flow rate.
Drying
Water evaporates very fast it’s exposed to hot, dry fast moving air. Conversely
water evaporates very slowly when it’s in cold, damp still air.

17. Temperature describes how much energy is available to drive evaporation.
On the warm day more water can evaporates because there is more thermal
energy available to do the work of evaporation.
Relative Humidity
In contrast water has less available thermal energy to drive evaporation
very slowly when it’s in cold out. Hence drying slowly considerably when
it’s cold.
Continued…

18. Relative humidity is important because the more moisture that’s already in the air,
lower the rate at which water will evaporate and less moisture that the air can
hold.
Relative humidity is a measure of the current amount of the water vapor in the air
relative to the total amount of water vapor that can hold exist in the air at it’s
current temperature, and is expressed as a percentage.
A relative humidity of 100% means the air can not contain any more water
vapor at that temperature.

19. Drying is also known as evaporation. The rate at which water evaporates
depends upon several factors, including the temperature, relative humidity and
air flow rate. Water evaporates very fast it’s exposed to hot, dry fast moving air.
Conversely water evaporates very slowly when it’s in cold, damp still air.
Drying

20. Dew point is the air temperature at which the air is saturated with water vapor.
Warm air can “HOLD” more water than cold air.
When air at a given temperature can not hold any more water it is fully saturated
and is at 100% relative Humidity.
Dew Point

21. Air flow rate is important because as water evaporates, the layer of air above the
water gradually becomes more saturated with water vapors. When Evaporated
moisture levels reach at saturation levels, drying essentially stops. Air Flow rate
increases the evaporation rate by “flushing” away the stagnant moist air above
the concrete.
Air Flow Rate

22. Wetting the surface of bare concrete creates a barrier of water that prevents the
moisture from inside the concrete from being drawn out when the surface
moisture evaporates. The film of water on the surface is relatively large
reservoir that can evaporate without affecting the moisture within concrete’s
pores. When concrete is covered in plastic, the air trapped under the plastic
quickly saturated with water vapor. When this happens drying essentially stops.
Moist Curing ?
Concrete needs to be moist for it to cure. Generally internal humidity needs
to be above 80 to 85% for complete hydration.

23. When concrete dries out, the suction forces developed when water evaporates
from the pores in the concrete can actually crush weak cement past. The longer
the concrete remain moist, the greater it’s strength and greater the resistance to the
suction forces.
Moist Curing !
This means fewer cracks and less shrinkage and curling.
Longer wet curing also reduces pore size, which means less moisture is
available to evaporate and the moisture has harder time escaping out of the
concrete.

24. Void Volume Relation With Harden Concrete
The volume of water in fresh cement paste or in fresh concrete is related
directly to the volume of empty pores space in hardened cement paste and
therefore hardened concrete.
Water cement ratio is therefore measure of the void volume relative to the
solid volume in hardened cement paste and it’s strength goes up as the void
volume goes down, so the lower the w/c , the lower the void volume/solid
volume and stronger hardened cement paste.

25. Free Water Porosity and Evaporable water at different
W/C.
W/C Porosity at Mixing
(Volume %)
Free Water Porosity
(Vol %)
Evaporable Water
(Vol %)
0.4 56.0 23.3 37.8
0.5 61.4 34.5 44.8
0.6 65.6 42.1 51.0
0.8 71.8 53.4 58.7

26.  The cement particles in fresh concrete, which are suspended in the mix water,
cannot pack together as efficiently when they are in close vicinity of much
larger solid object such an aggregate particle. This is general phenomenon
associated with particle packing, known as wall effect.
 In the case of concrete this effect is magnified by its shear stress exerted on the
cement paste by aggregate particle during mixing which tend to cause the
water separate from cement particles.
 The result is a narrow region around the aggregate particles with fewer cement
particles and thus more water. This is called Interfacial transition zone.

27.  The ITZ is region with higher W/C, and thus higher Porosity than the bulk paste. It
is not uniform, but varies point to point along each aggregate particle with an
average thickness 20 -40nm.
 The ITZ has important effect on concrete as creates weak link in the chain when
compared to the bulk cement past and aggregate particles.
 The ITZ is more permeable than bulk paste due to its higher porosity.

28.  In most cases the ITZ are linked (Percolated) creating continuous high
permeability phase across the structure.
 The permeability of concrete can be 1000 times greater than that of the
pure cement paste it contains.
 The durability of concrete is inversely related to the permeability.

30. Factors affecting Permeability

31. REDAWN HARD IS a concrete densifier and chemical
hardener compound that is a ready-to-use, colorless
liquid, consisting of reactive chemicals that deeply
penetrate the surface of concrete.
REDAWN HARD is specifically designed to produce
hardened, dust-proofed and improved chemically resistant
surfaces wherever it is applied. Through a chemical
reaction process.
REDAWN HARD penetrates through the concrete and
chemically solidifies the components into a homogeneous
concrete mass. Besides its densifying and hardening
action, REDAWN-HARD solidifies the concrete,
eliminating dusting, rotting, and pitting.
What is “REDAWN-HARD” Colloidal Silica Works ?

32. How does “REDAWN-HARD” Colloidal Silica Works ?
When used on a concrete surface,
REDAWN-HARD penetrates progressively through
the concrete and chemically converts the weak
calcium hydroxide and calcium carbonate
compounds in the concrete to form beneficial calcium
silicate hydrate (CSH) producing a hard, dense, and
sealed surface.
The process is basically a chemical reaction between
the free lime or calcium hydroxide . REDAWN-
HARD Chemically converts
weak aspects into good ones, through a process of
crystalline.
Home

33. Penetration through micro Capillary.

34. Penetration through micro Capillary.

35. .
.
.
Sr. No. Average
Consumption
Sqft/Liter
Chemical
Requirement
@25 %
Increased
Total
Quantity
% Ration of
cement & Silicate
Hardner
1 40 250 62.5 312 10.5%
2 35 285 71.25 356 11%
3 30 333 83.33 416.3 13%
4 25 400 100 500 16%
5 20 500 125 625 21%
6 10 1000 250 1250 42%
7 05 2000 500 2500 84%
Calculation of Colloidal Silica Based Hardener

36.  In densification system, Client should always be in concern of
Ratio i.e.. Liquid Hardener to cement used in 10 MM layer’s
concrete and Ratio should not be less then 7.44 % (minimum
Value).
 The ratio of Liquid hardener depends upon water cement ratio
adopted during concreting and also on finishing system of
concrete. Floor laid is power trowelled or IPS flooring system.

37. Thanks a Lot….