HA, produced after burning of Rice husks (RH) has high reactivity and pozzolanic property. Indian Standard code of practice for plain and reinforced concrete, IS 456- 2000, recommends use of RHA in concrete but does not specify quantities.

1. THE EFFECT OF RICE HUSK
ASH ON STRENGTH AND
PERMEABILITY OF CONCRETE

2. Introduction
 The production of cement is costly, consumes high energy,
depletes natural resources and emits huge amounts of
greenhouse gases (1 ton of cement production emits
approximately 1 ton of CO2). Consequently, environmental
degradation, pollution and health hazards problems
associated with cement industries, have come under scrutiny.
 So, now a day’s many people are trying to use industrial and
agricultural wastes in concrete. These wastes otherwise pose
several environmental problems.

3. Objectives
 To investigate compressive strength properties of
concrete containing different percentage of Rice Husk
Ash
 To investigate the permeability properties of concrete
containing different percentage of Rice Husk Ash
 To determine the optimal replacement of cement with
Rice Husk Ash, by comparing the results of compressive
strength and permeability tests.

4. Methodology (Detail of
Tests)
Name of
test
Size of
specimen
(mm)
No. of
mix
No. of
specimen
for each
mix
Total no.
of
specimen
Compressive
strength test 150×150×15
0
4 (0%, 15%,
25%, 35%)
6 (3-7 Days,
3-28 Days)
24
Permeability
Test
150x150x150
4 (0%, 15%,
25%, 35%)
6 (3-7 Days,
3-28 Days) 24

5. All the
specimen were
cast with M25
mix
The specimen
were taken out
from the mould
after 24 hours
and cured for
7/28 days.
Specimen of cubes
were tested for
‘Compressive
Strength’ and
‘Coefficient of
Permeability’ and
the final results
were analysed to
find the optimal
percentage
replacement of
cement with Rice
Husk Ash (RHA)
Methodology

6. Material used in the experimental
investigation
Cement
Water
Coarse Sand
Rice Husk Ash
Coarse
Aggregate

7. Continue……..
Ordinary Portland Cement of grade – 43 (source J.K
Cement)
Rice Husk Ash used in the study has been obtained from
NK Enterprises, Singhania House, Jharsuguda, Orissa,
India
Water- Tap water was used in concrete masonry

8. Rice Husk Ash OPC
Fine
Aggregates
Coarse
Aggregates

9. Rice Husk Ash
 Rice husk is one of the main agricultural residues obtained
from the outer covering of rice grains during the milling
process. Rice Husk Ash is obtained from burning of Rice
Husk, which is the by-product of rice milling. It is estimated
that 1,000 kg of rice grain produce 200 kg of Rice Husk
after burn.
 The rice husk ash had no useful application and had usually
been dumped into water streams and caused pollution until it
was known to be a useful mineral admixture for concrete.

10. • Standard Consistency of the cement paste = 29.5
• Initial setting time of cement = 115min
• Final setting time of cement = 220min
• Specific gravity of cement = 3.38
Test on cement
• Fineness modulus of fine aggregates =2.50
• Specific gravity of fine aggregates= 2.65
Test on fine aggregates
• Specific gravity of coarse aggregates= 2.61
• Fineness modulus of coarse aggregates =7.68
Test on coarse aggregates

11. Mix Design for M25 Grade
Concrete
Table of final mix
proportion (Wt. in Kg)/m3
concrete
Cement
Fine
Aggregat
e
Coarse
Aggregat
e
Water
Cement
ratio
1 1.3 2.9 0.45

12. Preparation, casting and curing
of concrete cubes

13. Testing Methods
Compressive strength
test
Cube failure after
compression test
Compression testing machine

14. Permeability
 Permeability of concrete generally refers to the rate at
which water or other aggressive substance (sulphates,
chlorides ions, etc.) can penetrate concrete.
 Low permeability of concrete to moisture and gas is the
first line of defence against: frost damage, acid attack,
sulphate attack, corrosion of steel embedment and
reinforcements, carbonation, alkali-aggregate reaction,
and efflorescence.

15. Methods For Testing Permeability
(IS 3085:1965)
 Constant flow Method
Darcy’s law has been used to determine the co-efficient of
permeability.
The equation used is
Ks=
Where, Ks - Coefficient of saturated permeability (m/s)
Q - Volume of flow rate (m3/s)
A -Cross-sectional area (m2)
L -Specimen thickness in the direction of flow
(m)

16. Permeability test
Permeability apparatus Permeability mould
Water reservoir
and pressure
controler
Air
Chamber

17. Continue……
Permeability test Set-Up (Schematic)Typical Details of Permeability Cell

18. Sealing of
specimen
(1) Filling pieces of jute rope (2) Filling mixture of lac & wax
(3) Filling Epoxy injection grout (4) Applying Sikadur 31 compound(Epoxy Grou

19. Leakage testing & Running the
test
 Fill the water reservoir and apply the desired pressure
(10 Kg/cm2) and note the initial gauge reading.
 After steady state of flow is reached, put the empty
beaker below the mould and note the time and pressure
on the gauge
 Note the discharge passed in a particular time interval
and at an average pressure on gauge.
 From the Darcy's law find the coefficient of
permeability.

20. Result and Discussion
Type of Mix
RHA (Kg) OPC (Kg)
Compressive
Strength
(MPa)
Average
Compressive
Strength
(MPa)
Percentage
Improvement w.r.t.
M0 Mix
M0
(0%)
19.84
21.24
20.56
20.55 ----
M1
(15%)
24.40
24.91
25.46
24.92 17.54
M2
(25%)
24.76
21.05
21.50
22.44 8.42
M3
(35%)
19.00
18.10
17.16
18.08 -13.66
Values of Compressive Strength (7-days curing)

21. Continue……
Type of Mix
RHA (%)
Compression
Strength (MPa)
Average
Strength
(MPa)
Ratio of
RHAC/OPC
Percentage
Improvement
w.r.t. OPC
M0 0%
33.41
31.23
30.30
31.64 ---- ----
M1 15%
34.26
34.56
35.00
34.61 1.09 8.58
M2 25%
33.35
33.20
31.80
32.78 1.03 3.47
M3 35%
30.20
29.78
28.98
29.65 0.93 -6.71
Values of Compressive Strength (28-days curing)

22. Compressive Strength of different
mixes (7 & 28 days)
20.55
24.92
22.44
18.08
31.64
34.61
32.78
29.65
0
5
10
15
20
25
30
35
40
M0 M1 M2 M3
CompressiveStrength(MPa)
Concrete Mix
7 days
28 days

23. Permeability test results
Mix
Sample
Discharge
Q (ml)
Time
T (Hrs)
Head of
water
H (m)
Co-efficient of
permeability, K(m/sec)
X 10-12
Avg. K(m/sec) X
10-12
M0 16
18
18 68.67
71.12
23.97
26.04
25.01
M1 12
14
18 73.58
76.03
16.78
18.94
17.86
M2 7
10
18 66.22
78.48
10.88
13.11
12.00
M3 15
16
18 68.67
73.58
22.47
22.37
22.42
Values of coefficient of permeability for 7-days water curing

24. Coefficient of permeability of RHAC at
7-days water curing
25.01
17.86
12
22.42
0
5
10
15
20
25
30
M0 M1 M2 M3
CoefficientofPermeability(10-12m/s)
Concrete Mix

25. Continue……
Mix
Sample
Discharge
Q (ml)
Time
T (Hrs)
Head of
water
H (m)
Co-efficient of
permeability, K(m/sec)
X 10-12
Avg. K(m/sec) X
10-12
M0 8
10
18 63.77
63.77
12.91
16.13
14.52
M1 6
7
18 68.67
71.12
8.99
10.13
9.56
M2 4
4
18 73.58
71.12
5.6
5.77
5.69
M3 9
8
18 66.22
68.67
13.98
12.0
13.00
Values of coefficient of permeability for 28-days water curing

26. Coefficient of permeability of RHAC at
28-days water curing
14.52
9.56
5.69
13
0
2
4
6
8
10
12
14
16
M0 M1 M2 M3
CoefficientofPermeability(10-12m/s)
Concrete Mix

27. Coefficient of Permeability of all mixes
at both 7 and 28-days water curing
25.01
17.86
12
22.42
14.52
9.56
5.69
13
0
5
10
15
20
25
30
M0 M1 M2 M3
CoefficientofPermeability(10-12m/s)
Concrete Mixes
7 days
28 days

28. Permeability of concrete is influenced
primarily by following factors:
 The nature of the hardened cement paste
 Porosity and interconnectivity of pores in the cement
paste and micro-cracks in the concrete.
 w/c ratio
 Degree of hydration
 The degree of compaction
 The type and quantity of constituent materials. (fine
cement tends to reduce permeability, well graded
aggregate tends to decrease permeability)

29. Conclusions
 The coefficient of permeability of RHAC is significantly
lower than that of OPC for all percent changes.
 The coefficient of permeability of RHAC decreases for
15 % & 25 % replacement but it starts increasing at 35%
replacement for cement.
 The permeability of OPC and RHAC decreases with
increase in curing period of samples.
 The addition of RHA had a significant effect on the
compressive strength of concrete. Compressive strength
of concrete increases with the addition of RHA upto a
certain level, after which it decreases.
 Optimal cement replacement level (by RHA) is 25%, for
which the compressive strength is maximum.

30. Continue…….
 The compressive strength is maximum at 15%
replacement and then it starts decreasing for both 7
and 28 days cured specimens.
 With 25% replacement the compressive strength of
cubes is nearly equal but slightly above then the
OPC mix concrete specimens, but at 35%
replacement the strength is less then the OPC mix
for both 7 and 28 days cubes.
 The compressive strength of OPC & RHAC
increases with increase in curing period of samples.
 The permeability of all mixes decreases with
increase in compressive strength as compared to
control concrete mix accept at 25% replacement.

31. Continue…….
 The results obtained from this study indicates that up to
25% of RHA could be advantageously blended with
cement without adversely affecting the strength and
permeability properties of concrete.