Mechanical properties and durability of rice husk ash concrete.

Ramasamy, V. ; Biswas, S.

Introduction Concrete is a widely used construction material for various types of structures due to its structural stability and strength. The Indian Construction Industry is today consuming about 400 million tones (MT) of concrete every year and it is expected that this may reach a billion tones in less than a decade. All the materials required to produce such huge quantities of concrete come from the earth's crust. Thus it deflects its resources every year creating ecological strains.

On the other hand human activities on earth produce solid wastes in considerable quantities of over 2500 MT per year, including industrial wastes, agricultural wastes and wastes from rural and urban societies. Recent technological development has shown that these materials are valuable as inorganic and organic resources and can produce various useful products. Amongst the solid wastes, the most prominent ones are fly ash, blast furnace slag, rice husk (converted into ash), and silica fume and demolished construction materials.

From the mid of 20th century, there had been an increase in the consumption of mineral admixtures by the cement and concrete industries. This increasing demand for cement and concrete is met by partial cement replacement. Substantial energy and cost savings can result when industrial by-products are used as a partial replacement for the energy intense Portland cement. The use of by-products is an environmental--friendly method of disposal of large quantities of materials that would otherwise pollute land, water and air. The current cement production rate of the world, which is approximately 1.2 billion tones / year, is expected to grow exponentially to about 2 billion tones/year by 2010. Most of the increase in cement demand will be met by the use of supplementary cementing materials, as each ton of Portland cement clinker production is associated with a similar amount of C[O.sub.2] emission which is a major source of Global warming. By reducing the use of Portland cement, C[O.sub.2] emission is controlled. Rice Husk, an agricultural waste is one of such materials, which constitutes about one fifth of the 580 million metric tones of rice produced annually in the world.

Due to growing environmental concerns and the need to conserve energy and resources, efforts have been made to burn the husks at a controlled temperature and atmosphere and to utilize the Rice Husk ash (RHA) so produced as a supplementary cementing material. Prior to 1970, RHA was usually produced by uncontrolled combustion and the ash so produced was crystalline and poor pozzolonic properties. In 1973, Mehta published the first of several papers describing the effect of pyro processing parameters on the pozzolonic reactivity of RHA. Based on his research, Pitt designed a Fluidized bed furnace for controlled burning of rice husks.

India produces 25 million tones of rice husks annually and it is estimated that approximately 12 million tones are readily available for disposal from the rice mills. By burning the rice husk under a controlled temperature and atmosphere, a highly reactive RHA is obtained. The pozzolonic property of RHA is not only effective in enhancing the strength of concrete, but also improves the impermeability of concrete. However, very limited studies are reported detailing the usage of RHA in concrete as an admixture in Indian conditions.

Many excellent publications have shown that RHA can be used as a cement replacement material to produce high strength concrete and increased durability of concrete such as permeability, initial surface absorption test [ISAT], and Chloride resistance. This paper reports an investigation of using RHA as a supplementary cementitious material to produce durable concrete

Experimental Programme

Materials Used

Ordinary Portland cement (OPC) of 53 grade obtained from single source was used in this investigation. The properties of cement tested as per IS: 4031-1988 are given in Table 1 and is found to conform to various specifications of IS: 12269-1987. Locally available river sand, with a specific gravity of 2.60 and fineness modulus of 2.64 was used as fine aggregate. The loose and compacted bulk density value are 1575 and 1726 kg/[m.sup.3], respectively. The crushed blue granite aggregate with a maximum size of 20mm having specific gravity and fineness modulus of 2.80 and 7.20 respectively was used.

The commercially available RHA (Hyper 2000) procured from M/S. K.C. Contech, Chennai with specific gravity of 2.01 was used as cement replacement material. The chemical composition and physical properties of the RHA is presented in Table 2. Sulphonatednaphalene based super plasticizer (SP) and potable water was used for the preparation of the concrete mixtures.

Mix Proportions

The mix proportions of M30 and M60 grade concrete mixtures were designed based on recommendations of IS: 10262 and ACI committee 211.4R.93 without RHA and SP. The identification of mix proportions and quantity of materials taken for one meter cube of concrete mixtures are given in Tables 3 and 4. Concrete mixtures were prepared with cement replacement levels of 0%, 5%, 10%, 15% and 20% by RHA with and without SP.

Preparation of Test Specimens

The ingredients for the various mixes were weighed and prepared the mixes by using a tilting drum type concrete mixture machine. Precautions were taken to ensure uniform mixing of ingredients. The specimen were cast in steel mould and compacted on a table vibrator. The specimens of 100mm x 100mm x 100mm size of cube, 100mm diameter x 200mm high cylinder specimens, 100mm x 100mm x 500mm size of prisms were cast for the determination of compressive strength and water absorption at different ages and for the determination of split tensile and flexural strength, respectively. Curing of the specimens was started as soon as the top surface of the concrete in the mould was stiff enough. The initial curing was carried out by spreading wet gunny bags over the mould for 24 hours after the casting, the specimens were demoulded and placed immediately in water tank for further curing.

Compressive, Split Tensile and Flexural Strengths

Compressive strength of various mixes of concrete cubes was determined after 7, 28, 56, 90 and 180 days curing as per IS9013-1978. Split tensile strength test was conducted on concrete cylinder after 28 days and 56 days of curing as per IS 5816-1999. Flexural strength test was conducted on Concrete prism after 28 and 56 days of curing as per IS 516-1959

Tests for Saturated Water Absorption and Porosity

The water absorption and porosity values for various mixtures of concrete were determined on 100mm cubes as per ASTM C 642. The specimens were taken out of curing tank at 60 days to record the water saturated weight (Ws). The drying was carried out in an oven at a temperature of 105[degrees]C. The drying process was continued until the difference in main between two successive measurements agreed closers. Oven dried specimens were weighed after they cooled to room temperature ([W.sub.d]). Using these weights, saturated water absorption (SWA) was calculated by SWA = (([W.sub.s]-[W.sub.d])/[W.sub.a]) X 100

Where, [W.sub.s] is the weight of specimen at fully saturated condition

[W.sub.d] is the weight of oven-dried specimen

The porosity obtained from absorption test is designated of effective porosity. It is determined by using the following formula,

Effective porosity = (volume of voids) / (bulk volume of specimen)

The volume of voids was obtained from the volume of water absorbed by an oven dry specimen (or) the volume of water lost on oven drying a water saturated specimen at 105[degrees]C to constant mass. The volume of specimen is given by the difference in mass of the specimen in air and it's mass under submerged condition in water.

Rapid Chloride Permeability Test (RCPT)

This test was conducted as per ASTM C 1202-94. Concrete disc of size 100 mm diameter and 50 mm thickness with and without rice husk ash were cast and allowed to cure for 28 days and 90 days. After curing the concrete specimens were subjected to RCPT test by impressing 60 V. Two halves of the specimens are sealed with PVC container of diameter 90 mm. One side of the container is filled with 3% NaCl solution (that side of the cell will be connected to the negative terminal of the power supply). Current is measured at every 30 minutes up to 6 h. Chloride contamination and temperature at every 30 min was also monitored. From the results using current and time, chloride permeability is calculated in terms of Coulombs at the end of 6 h[11].

The limitations of Rapid chloride ion permeability as per ASTM C 1202 are given in Table 5

Initial Surface Absorption Test (ISAT)

The ISAT specified in BS 1881 part 5 is used for measuring initial surface absorption of concrete. The test is carried out on 28 & 90 days cured concrete samples. Samples were properly cleaned and dried which is the critical condition for the test. The test consists of the measurement of water flow into the test specimen through known surface.

Discussion of Test Results

Workability

The workability of RHA concrete has been found to decrease with increase in RHA replacement. So it appeared that the addition of SP might improve the workability. The increase in the percent replacement of RHA caused the increase in the dosage of SP because of the fineness of RHA. In M60 grade concrete the addition of SP was added for maintaining the constant slump the workability of various replacement of RHA are presented in Table 6

Compressive Strength of Concrete

The effect of RHA replacement on compressive strength of M30 and M60 concretes are presented in Fig 1 to 4 at 7,28,56,90 and 180 days for curing with and without RHA as an admixture. It is observed that there is an increase in compressive strength with a certain percentage of replacement of RHA with plasticizer and beyond certain percentage a trend of decrease in strength has been found.

It has been observed that there is a reduction of 30% of strength at 20% of replacement. Presumably because of low workability there might not have been adequate reaction to take place resulting in low strength. Further it is found that the increase in strength beyond 28 days of curing up to 180 days have not shown any appreciable strength increase. This behaviour attributes that for all practical purposes 28 days strength may be taken as the defining strength for RHA based concrete also.

[FIGURE 1 OMITTED]

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

[FIGURE 4 OMITTED]

Effect of RHA and SP on Split Tensile Strength

The reduction in split tensile strength was observed in both the concrete mixtures without super plasticizer. It varies from 8.3 to 33.57 and 7.73% to 27.78 at 28 days and 56 days respectively, for the variation of RHA content of 5% to 20% of M30 grade concrete. In M60 grade concrete mixtures the reduction varies from 12.04 to 32.87 and 10.82% to 35.50 at 28 days and 56 days, respectively. The same trend was observed for both the mixtures with SP that are shown in fig 5 -6.

[FIGURE 5 OMITTED]

[FIGURE 6 OMITTED]

Effect of RHA on Flexural Strength

The experimental investigation it is observed that the cement replacement by RHA up to 10% shows the marginal increase in flexural strength. For M30 grade concrete, it was 9.55% and 1.06 at the age of 28 days 8.37 and 2.28 at age of 56 days for the replacement of 5% and 10% without SP respectively. But the addition of SP showed strength developed of 3.68% and 7.02% at 28 days, 2.87 and 7.01 at 56 days for the RHA content of 5% and 10% respectively.

Replacement of cement by large quantities of RHA showed lesser flexural strength than control concrete. The reduction in strength at 15% and 20% rise husk content are 10.16 and 16.26 at 28 days and 9.13 and 15.97 at 56 days, without SP respectively.

The trend of decrease in strength for increase in RHA content was also observed in M60 grade concrete mixtures without SP. Addition of SP in M60 grade concrete mixtures showed the flexural strength gain of 7.35% and 4.41% at 28 days, 2.7% and 0% at 58 days for 5% and 10% cement replacement, respectively. Reduction on flexural strength was observed for both the mixtures with 15% and 20%, replacement by RHA. The performance levels were shown in fig 7 -8.

[FIGURE 8 OMITTED]

Effect of RHA And SP on Saturated Water Absorption & Porosity Property of Concrete The test results of saturated water absorption of concrete with and without SP for various % of replacements are shown in tables 7 to 10.

Effect of RHA and SP on Permeability

Results on Rapid chloride ion permeability at the age of 28 and 90 days with various percentage of RHA with and without SP are given in Table 11 & 12.

The charge conducted by the specimens in coulombs was reduced to ASTM C1202 equivalent chloride-ion permeability values by taking into consideration the dimension of the specimen, voltage applied and the test duration.

It was observed that most of chloride ion permeability values fall in the range of very low (100-1000 coulombs) category. The increase in RHA content reduces the permeability of chloride ion for both the concrete mixtures. The concrete mixtures with the addition of SP showed very low permeability at higher content of RHA. The SNF based SP showed very low permeability values in M30 and M60 concrete mixtures respectively.

The same was observed in M60 grade concrete mixers with and without SP. The M60 grade concrete mixtures show higher resistance to chloride ion diffusion than the M30 grade concrete. The incorporation of rice husk ash results in smaller crystalline products and final pores in the hydrated paste interface which results in decrease of permeability.

Water Permeability by Initial Surface Absorption Test (ISAT)

The test results of initial surface absorption of concrete with and without SP for various percentage of RHA are shown in Table 13 & 14. The average rate of penetration of water at the end of 24 hours through M30 grade concrete at 28 and 90 days without SP were 15.80, 8.20, 7.10 6.2 8.50 ml/[m.sup.2]/hr and 11.0, 6.50, 4.80, 2.30, 4.60ml/[m.sup.2]/hr at 0, 5, 10, 15 and 20% RHA contents, respectively which is about the average rate of penetration of water at 24 hours through SNF based SP in M30 grade concrete mixtures were 9.30, 5.80, 4.30, 2.80 and 3.20 ml/[m.sup.2]/hr and 5.15, 2.80, 1.90, 1.20 and 1.60ml/[m.sup.2]/hr at 28 and 90 days respectively.

The same behaviour was observed in M60 grade concrete mixtures with and without SP. The M60 grade concrete mixtures show high degree of impermeability to water than the M30 grade concrete mixtures. The HPC mix reported in thesis was found to possess very low surface permeability to water. In view of this the average rate of penetration of water, values obtained for various mixes reported in this study could be considered reasonable. This result implies that incorporation of RHA is beneficial to reduce the permeability of concrete.

Conclusion

RHA is highly reactive pozzolanic material and can be used as a supplementary cementing material to produce High-Performance concrete.

* Due to the high specific surface of the RHA, the concrete incorporating RHA required higher dosage of the SP to achieve the workability.

* The addition of RHA causes an increase in the compressive strength due to pozzolanic effects up to 10% replacement levels.

* Based on the results of Split Tensile Strength, it is to state that there is no substantial increase in tensile strength due to addition of RHA.

* The flexural strength studies indicate that there is marginal improvement with 10% RHA replacement for both the concrete grades.

* The RHA Concrete had excellent resistance to chloride ion penetrations and the charge passed coulombs was below 1000 at 28 and 90 days for both the mixtures, which was well below that of the controlled concrete.

* The RHA based concrete mixtures fall under the "Very low permeability" category at all the ages.

* The surface permeability of RHA concrete specimens by water are also decreased when compared with the controlled Concrete.

* RHA concrete exhibited lower initial surface absorption value to that of control concrete indications the beneficial effect of incorporation RHA to reduce the permeability of Concrete.

* Optimum replacement of cement by RHA is 15 % for both the mixes. Further increase in RHA shows even through higher permeability values but lesser than the control Concrete.

Acknowledgement

The results reported here are based on investigations carried out in the School of Mechanical and Building Sciences, Vellore Institute of Technology, Vellore. The authors thankfully acknowledge the Management of VIT and Dr. P. Purushothamaraj, Director, Adhiparasakthi Engineering College, Melmaruvathur, for the support extended.

References

[1] Ganesan., K, Rajagopal., K, Thangavel., K, Selvaraj., R, Saraswathi., V, "Rice Husk Ash-As Versatile Supplementary Cementitious Material, " Indian Concrete Institute Journal, Mar 2004, PP-29-34.

[2] Mehta, P.K "Properties of Blended Cements Made From Rice Husk Ash", Journal of American Concrete Institute, Vol.74, No.9, September 1977, PP. 440-442.

[3] Mehta. P.K. and Folliard. K.J., "Rice Husk Ash-A Unique Supplementary

Cementing Material Durability Aspects"-ACI. SP 154-28, 1995 USA, PP 531-541.

[4] Moayad, N, Al-Khalaf And Hana A. Yousift, "Use Of Rice Husk Ash In Concrete" The International Journal Of Cement Composites And Lightweight Concrete, Vol6, No.4, 1984, PP 241-248.

[5] Ramarao., G.V. And Seshagiri Rao., M.V., "High Performance Concrete with Rice Husk Ash as Mineral Admixture", Indian Concrete Institute Journal, Jan 2003, PP 17-21.

[6] Cook, D.J., "Rice Husk Ash"; in cement Replacement Materials, concrete Technology and Desigh, Vol.3, Ed:R.N. Swamy, Surrey University Press, UK, 1996, 259pp.

[7] Rao. M.V.S., Rao., K.R.M. Janardhana and Ravindra Kumar, "High Flyash Concretes With Rice Husk Ash as an Admixture." IE (1) Journal-CV Vol. Aug-1999 PP 57-63.

[8] Zhang, M.H. And Malhotra,V.M., "High-Performance Concrete Incorporating Rice Husk Ash As A Supplementary Cementing Materials", ACI. Materials Journal 93 (6). 1996, PP. 629-636.

[9] Mehta.P.K. And Folliard.K.J., "Rice Husk Ash-A Unique Supplementary Cementing Material Durability Aspects"-ACI. SP 154-28, 1995 USA, PP 531-541.

[10] IS 456-2000, "Plain And Reinforced Concrete Code Of Practice", Bureau Of Indian Standards, New Delhi.

[11] ASTM C1202, Electrical Indication of Concrete's Ability to Resist Chloride Ion Penetration, Annual Book of Americal Society for Testing Materials Standards, Vol.C04.02, 1993.

V. Ramasamy and Dr. S. Biswas

Research Scholar, Vellore Institute of Technology, School of Mechanical and Building Sciences, Vellore, India. Email: rams_apec@yahoo.co.in Professor, School of Mechanical and Building Sciences, Vellore Institute of Technology - University, Vellore, India

Table 1: Physical Properties of Cement

S.No Property Result

1. Normal Consistency 32%
 Setting times
2. Initial 65 mins.
 Final setting time 250 mins.
3. Specific gravity 3.15
4. Fineness of cement
 (By 90 micron sieve) 5 %retained
5. Soundnes of cement 2 mm
 (Le chatlier expansion value)
6. Compressive strength
 7 days 37 N/mm 2
 28 days 58 N/mm 2

Table 2: Physical and Chemical Analysis of RHA Used

 1. Finess passing 45 micron 96%
 2. Specific Gravity 2.06
 3. Bulk Density 0.675 g/cc
 4. Silicon dioxide (Si[O.sub.2] 87.20%
 5. Aluminium oxide ([Al.sub.2][O.sub.3]) 0.15%
 6. Ferric oxide ([Fe.sub.2][O.sub.3]) 0.16%
 7. Calcium oxide (CaO) 0.55%
 8. Magnesium oxide (MgO) 0.35%
 9. Sulphur trioxide (S[O.sub.3] 0.24%
10. Carbon (C) 5.91%
11. Loss on Ignition 5.44%

Table 3: Mix Proportion for M 30 Grade Concrete Mixtures

Mix Designation BC BR1 BR2 BR3

Ricehusk aSK Present (%) 0 5 10 15
w/b rati 0.43 0.43 0.43 0.43
Cement (Kg/[m.sup.3] 420 399 378 357
Ricehusk ash (Kg/[m.sup.3] 0 21 42 63
Sand (Kg/[m.sup.3] 621 582 542 503
Coarse aggregate (Kg/[m.sup.3] 1108 1108. 1108 1108
Water (lit/[m.sup.3] 180.60 180.60 180.60 180.60

Mix Designation BR4

Ricehusk aSK Present (%) 20
w/b rati 0.43
Cement (Kg/[m.sup.3] 336
Ricehusk ash (Kg/[m.sup.3] 84
Sand (Kg/[m.sup.3] 464.
Coarse aggregate (Kg/[m.sup.3] 1108
Water (lit/[m.sup.3] 180.60

Note : BC--Control Concrete, BR1-5% RHA, BR2--10 % RHA, BR3-15%
RHA, BR4-20% RHA

Table 4: Mix Proportion for M 60 Grade Concrete Mixtures

Mix Designation CC CR1 CR2 CR3 CR4

RHA Present (%) 0 5 10 15 20
w/b ratio 0.35 0.35 0.35 0.35 0.35
Cement (Kg/[m.sup.3] 474 447 420 391 366
RHA (Kg/[m.sup.3] 0 27 54 81 108
Sand (Kg/[m.sup.3] 636 585.10 535.61 483.21 433.72
Coarse aggregate 1113 1113 1113 1113 1113
(Kg/[m.sup.3]
Water (lit/[m.sup.3] 166 166 166 166 166

Note: CC--Control Concrete, CR1-5% RHA, CR2--10 % RHA, CR3-15%
RHA, CR4-20% RHA

Table 5: Limitations of Chloride ion Permeability

S.No. Charge Passed in coulumbs Limits as per ASTM C 1202

1 >4000 High Permeability
2 2000 to 4000 Moderate Permeability
3 1000 to 2000 Low Permeability
4 100 to 100 Very Low Permeability
5 <100 Negligible Permeability

Table 6: Workability Property of M30 Grade RHA concrete with and
without SP

 Workability Workability with SP
 without SP
 Dosage of SP (by
Sl. Mix RHA Slump weight of Binder Slump C.F
No (%) (mm) C.F (%) (mm)

1. BC 0 15 0.92 0.4 20 0.93
2. BR1 5 10 0.83 0.4 20 0.92
3. BR2 10 5 0.82 0.8 15 0.86
4. BR3 15 0 0.80 1.40 10 0.82
5. BR4 20 0 0.77 2.80 7 0.79

Note: BC--Control Concrete, BR1-5% RHA, BR2-10 % RHA, BR3-15%
RHA, BR4-20% RHA

Table 7: Saturated Water Absorption of M 30 Grade Concrete Mixtures

 SP Content
 RHA (by weight
 Mix content of binder)
S.No. Designation (%) (%)

1. BC 0 0.40
2. BR1 5 0.40
3. BR2 10 0.80
4. BR3 15 1.40
5. BR4 20 2.80

 Saturated Water Absorption @ 60
 Days (%)
 Mix
S.No. Designation Control without SP With SP

1. BC 1.62 1.28
2. BR1 1.68 1.34
3. BR2 1.74 1.42
4. BR3 1.88 1.56
5. BR4 2.15 1.98

Table 8: Saturated Water Absorption of M 60 Grade Concrete Mixtures

 SP Content
 RHA (by weight
 Mix content of binder)
S.No. Designation (%) (%)

1. CC 0 1.8
2. CR1 5 2.0
3. CR2 10 3.2
4. CR3 15 4.5
5. CR4 20 5.8

 Saturated Water Absorption @ 60
 Days (%)
 Mix
S.No. Designation Control Without SP With SP

1. CC 1.3 1.58
2. CR1 1.5 1.72
3. CR2 1.61 1.78
4. CR3 1.74 1.92
5. CR4 1.92 2.28

Table 9: Porosity of M 30 Grade Concrete Mixtures

 SP Content
 RHA (by weight
 Mix content of binder)
S.No. Designation (%) (%)

1. BC 0 0.40
2. BR1 5 0.40
3. BR2 10 0.80
4. BR3 15 1.40
5. BR4 20 2.80

 Saturated Water Absorption @ 60
 Days (%)
 Mix
S.No. Designation Control Without SP With SP

1. BC 3.9 2.90
2. BR1 4.3 3.5
3. BR2 4.9 3.8
4. BR3 5.2 4.2
5. BR4 5.7 4.9

Table 10: Porosity of M 60 Grade Concrete Mixtures

 SP Content
 RHA (by weight
 Mix content of binder)
S.No. Designation (%) (%)

1. CC 0 1.8
2. CR1 5 2.0
3. CR2 10 3.2
4. CR3 15 4.5
5. CR4 20 5.8

 Saturated Water Absorption @ 60
 Days (%)
 Mix
S.No. Designation Control With SP With SP

1. CC 3.6 3.9
2. CR1 3.9 4.3
3. CR2 4.2 4.8
4. CR3 4.4 5.10
5. CR4 4.9 5.5

Table 11: Rapid Chloride ion Diffusion of [M.sub.30] Grade Concrete
with & without SP

 SP
 Content
 RHA (by weight
 Mix Content of binder)
S.No. Designation (%) (%)

1. BC 0 0.40
2. BR1 5 0.40
3. BR2 10 0.80
4. BR3 15 1.40
5. BR4 20 2.80

 Charge Passed in Coulombs

 Control
 (Without SP) With SP
 Mix at 28 at 90
S.No. Designation days days at 28 day sat 90 days

1. BC 2420 945 980 945
2. BR1 1146 540 946 540
3. BR2 675 480 590 480
4. BR3 570 260 470 260
5. BR4 420 218 380 218

Table 12: Rapid Chloride ion Diffusion of [M.sub.60] Grade Concrete
With & without SP

 SP
 Content
 RHA (by weight
 Mix Content of binder)
S.No. Designation (%) (%)

1. CC 1.8 0
2. CR1 2.0 5
3. CR2 3.2 10
4. CR3 4.5 15
5. CR4 5.8 20

 Charge Passed in Coulombs

 Control
 (Without SP) With SP

 Mix at 28 at 90 at 28 day sat 90 days
S.No. Designation days days

1. CC 1740 840 920 790
2. CR1 920 590 780 540
3. CR2 560 390 535 400
4. CR3 410 290 390 260
5. CR4 340 220 310 210

Table 13: Water Permeability by initial Surface Absorption Test (ISAT)
of [M.sub.30] Grade Concrete With & without SP

 SP
 Content
 RHA (by weight
 Mix Content of binder)
S.No. Designation (%) %

1. BC 0 0.40
2. BR1 5 0.40
3. BR2 10 0.80
4. BR3 15 1.40
5. BR4 20 2.80

 Average rate of Penetration of water at
 24 hrs (ml/[m.sup.2]/hr) at age of

 Control (Without With SP
 SP)
 Mix at 28 at 90 at 28 day sat 90 days
S.No. Designation days days

1. BC 15.80 11 9.30 5.15
2. BR1 8.20 6.50 5.80 2.80
3. BR2 7.10 4.80 4.30 1.90
4. BR3 6.20 2.30 2.80 1.20
5. BR4 8.50 5.60 3.20 1.60

Table 14: Water Permeability by Initial Surface Absorption Test (ISAT)
of [M.sub.60] Grade With & without SP

 SP
 Content
 RHA (by weight
 Mix Content of binder)
S.No. Designation (%) %

1. CC 0 1.8
2. CR1 5 2.0
3. CR2 10 3.2
4. CR3 15 4.5
5. CR4 20 5.8

 Average rate of Penetration of water at
 24 hrs (ml/[m.sup.2]/hr) at age of

 Control (Without
 With SP
 Mix at 28 at 90
S.No. Designation days days at 28 day sat 90 days

1. CC 16.80 11.53 8.90 5.30
2. CR1 8.95 5.40 6.40 3.40
3. CR2 5.80 2.20 3.80 2.20
4. CR3 3.50 1.80 2.10 1.90
5. CR4 8.50 7.50 2.90 2.50