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Rice husk ash concrete thesis writing

Rice husk ash concrete thesis writing element or member under investigation

Sudisht Mishra. Faculty Civil Engineer. Deptt NERIST, Itanagar, Prof (Dr.) S. V. Deodhar. Principal, SSVPS BSD College of Engineering, Dhule.

Introduction

Workability, strength, and sturdiness are three basics qualities of concrete. Quantity of helpful internal work essential to overcome the interior friction to create full compaction known as as Workability. Size, shape, surface texture and grading of aggregates, water-cement ratio, utilization of admixtures and blend proportion are essential factors affecting workability. Strength would be to bear the preferred stresses inside the allowable factor of safety in expected exposure condition. The factor influencing the force are: quality of cement, water-cement ratio, grading of aggregates, amount of compaction, efficiency of curing, curing temperature, age during the time of testing, impact and fatigue. Durability is nutrition of shape, size and strength potential to deal with exposure conditions, disintegration and putting on under adverse conditions. Variation in concrete production, loading conditions operating existence and subsequent attack through the atmosphere factors are primary failing factor of concrete. Correctly compacted and cured concrete utilized in RCC remains substantially water-tight and sturdy till capillary pores and micro-cracks within the interior are interconnected to create pathways as much as surface.

Durability is principally affected by ecological exposure condition, freezing – thawing, contact to aggressive chemicals, type and excellence of constituent materials, water-cement ratio, workability, size and shape from the member, amount of compaction, efficiency of curing, effectiveness of canopy concrete, porosity and permeability.

Rice husk ash concrete thesis writing and it is observed that

During service existence of structures, transmission water and aggressive chemicals, carbonation, chloride ingress, leaching, sulphate attack, alkali-silica reaction and freezing-thawing are resulting degeneration. Loading and weathering inter link voids and micro-cracks contained in transition zone and network of same micro cracks will get linked to cracks on concrete surface which supplies primary mechanism from the fluid transport to interior of concrete. Subsequent increase of penetrability results in easy ingress water, oxygen, co2 and acidic ions etc into concrete resulting cracking, spalling, loss at mass, strength and stiffness.

Low permeability is essential to durability which is controlled by factors such as water-cement ratio, amount of hydration, curing, entrapped air voids, micro cracks because of loading and cyclic contact with thermal variations. Admixture improves workability, compactibility, strength, impermeability, potential to deal with chemical attack, corrosion of reinforcement and freezing – thawing etc. and as a result to durability. With this study durability is construed when it comes to porosity, moisture movement, surface strength, ultra seem pulse velocity and elasticity modulus of concrete. Better use of Grain Husk Ash (RHA), acquired by open field burning method, is made the decision for improving workability, durability and strength of concrete.

Grain Husk Ash

RHA, created after burning of Grain husks (RH) has high reactivity and pozzolanic property.

Rice husk ash concrete thesis writing of RHA is

Indian Standard code of practice for plain and reinforced concrete, IS 456- 2000, recommends utilization of RHA in concrete but doesn’t specify quantities. Chemical compositions of RHA may take a hit because of burning process and temperature. Silica content within the ash increases with greater the burning temperature. According to study by Houston, D. F. (1972) RHA created by burning grain husk between 600 and 700°C temperatures for just two hrs, contains 90-95% SiO2. 1-3% K2 O and 5% unburnt carbon. Under controlled burning symptom in industrial furnace, conducted by Mehta, PKay. (1992), RHA contains silica in amorphous and highly cellular form, with 50-1000 m 2 /g area. So utilization of RHA with cement improves workability and stability, reduces heat evolution, thermal cracking and plastic shrinkage. This increases strength development, impermeability and sturdiness by strengthening transition zone, modifying the pore-structure, blocking the big voids within the hydrated cement paste through pozzolanic reaction. RHA minimizes alkali-aggregate reaction, reduces expansion, refines pore structure and hinders diffusion of alkali ions towards the the surface of aggregate by micro porous structure.

Portland cement contains 60 to 65% CaO and, upon hydration, a substantial part of lime is released as free Ca(OH)2. that is mainly accountable for poor people performance of Portland cement concretes in acidic environments. Silica contained in the RHA combines using the calcium hydroxide and results excellent resistance from the material to acidic environments. RHA replacing 10% Portland cement resists chloride transmission, improves capillary suction and faster chloride diffusivity.

Pozzolanic result of RHA consumes Ca(OH)2 contained in a hydrated Portland cement paste, reduces prone to acidity attack and improves potential to deal with chloride transmission. This reduces large pores and porosity resulting really low permeability. The pozzolanic and cementitious reaction connected with RHA cuts down on the free lime contained in the cement paste, lessens the permeability from the system, improves overall potential to deal with CO2 attack and enhances potential to deal with corrosion of steel in concrete. Highly micro porous structure RHA mixed concrete provides escape pathways for that freezing water within the concrete, relieving internal stresses, reducing micro cracking and improving freeze-thaw resistance.

Non Destructive Tests (NDT)

NDT, systems needed for assessing strength operating feature, is understood to be an evaluation which doesn’t impair the intended performance from the element or member under analysis, transported out onsite, with ability to look for the durability and strength of critical constructions with no damage to.

For performing ND Tests, Rebound hammer, Protimeter-moisture measurement system, Porositester and pulse Ultrasound Non-Destructive Indicating Tester (PUNDIT) equipment are utilized.

Rebound hammer test is carried out to evaluate the relative strength of concrete in line with the hardness at or near its uncovered surface. Concrete Rebound Test Hammer is really a traditional instrument employed for the non-destructive testing of hardened concrete. This gives a simple and quick test way of acquiring an instantaneous symbol of concrete strength in a variety of areas of a structure. Knob of the instrument is stored verticle with respect towards the surface (i.e. ninety degree towards the surface) for measurement and it is push pressed in the bottom towards the top of concrete, hammer like seem is created. The button near the foot of the instrument is pressed to lock the indicator and studying is taken.

The top moisture is usually not seen to clean and restoring the dwelling after damage from storms, floods or fires. For uncovered or unseen structural damage, the undetected moisture damages strength, durability and reliability. The Protimeter Moisture Measurement Product is a effective and versatile instrument for calculating and diagnosing surface moisture in structures. This instrument directly displays moisture content (%) together with three conditions of fabric like DRY, WET and RISK condition. For implementing Protimeter operational modes are selected and knowledge is presented on the large, back lit live view screen display. Radio stations frequency sensor lies to ensure that many moisture readings is taken rapidly and simply.

Porositester contains of three glass tube accustomed to appraise the water transmission in concrete at atmospheric pressure. Tubes are fixed with vacuum plate and vacuum pump with no subsequent cleaning. Rubber seal placed within the tube supplies a defined contact the surface of dia 25 mm vertical or horizontal. Compressible seals on suction plate and tube permit secure fixing and to uneven surfaces. Current supply is supplied from the 12 V rechargeable battery. Vacuum plate is pressed from the faade having a wet sponge, motor is positioned on adhesion from the plate is checked. Test tubes are put underneath the clip and guaranteed firmly with screws. Test tubes are full of water to the zero mark and again refilled following the descent from the level by one or two ml and readings of volume of permeated water are noted lower for 15 minute test time. As reported by the manual of apparatus, water absorption coefficient A is calculated by utilizing following formula:

X=Amount (level) water permeated in ml.

d= Dia. of test tube in mm.

t= Duration of transmission within a few minutes.

Figure 1: Porositester

Figure 1 shows the Porositester pointed out above Pundit is really a highly reliable equipment for ultrasound pulse velocity teshon concrete. Pundit plus can be used to find out pulse velocity, (UPV) modulus of elasticity, tooth decay and cracks contained in the concrete. Devices are ruggedly designed for on-site reliability for straightforward, fast operation with integral RS232 interface, auto memory store for readings, large Liquid crystal display with exterior or electric batteries supply. The setup parameters are defined for that preferred mode of operation and particular values are displayed.

Workplan

Purpose of the work would be to read the results of Grain Husk Ash being an admixture on workability, strength, reliability of cement concrete and cement mortar. In line with the above, optimum dose of RHA is decided to boost the preferred qualities of concrete without causing any adverse result on other qualities.

Grain Husk from local Grain Mills was burnt completely in open field condition and sieved with 150 micron IS sieve. Grain Husk Ash percentage was gradual elevated from 7.5%, 10.%, 12.5%, 15.% and 17.5%. M20 grade nominal mix concrete (1. 1.5. 3) and cement mortar of proportion (1. 4). Coarse aggregate of 20 mm graded nominal size, river sand zone III type and 53 grades Pozzolana Portland Cement (PPC) were utilised with this work. For slump values 15 mm to 35 mm and compaction factor .85 to .90, water cement ratio for plain and RHA mixed concrete was .50 and .575 correspondingly. For casting concrete and mortar cubes, 150 mm steel cube moulds and 70.7 mm steel cube moulds were utilised. Each set Contained Six examples of plain concrete and 6 of RHA mixed. After 24 hrs of casting, samples were opened up and stored under plain tap water curing for 4 weeks. Later destructive and non-destructive tests were transported on group of three separate cubes and average values taken with this study.

Test Results
Compressive Strength

Compressive strength for RHA mixed concrete samples elevated up to 12.5% of RHA and decreased for greater % of RHA. Greatest strength was discovered 30.3 N/mm 2 adopted by 30.07 N/mm 2 for RHA composition 10.00% and 12.5% correspondingly. Compared to normal M20 mix samples, compressive strength decreased by 12.94% and 19.17% for 15.00% and 17.5% of RHA mixed concrete samples. Between RHA compositions 10% and 12.5%, compressive strength elevated very marginally (.80%) whereas same return was greatest (3.08%) between RHA compositions 7.50% and 10.00%.

Compressive strength of ordinary mortar cubes was 10.39 N/mm 2 and same elevated to 16.43 N/mm 2 and 17.44 N/mm 2 for RHA composition 7.5% and 10.00% correspondingly. For greater proportion of RHA, 12.50%, 15.00% and 17.50%, compressive strength decreased to 12.74 N/mm 2. 10.73 N/mm 2 and seven.71 N/mm 2 correspondingly. Maximum rise in strength was 67.85% adopted by 58.13% for 10.00% and seven.50% RHA composition correspondingly.

Rebound Hammer Test

Surface strength of M20 grade concrete cube was 20.05 N/mm 2. For RHA mixed samples, same values elevated to no more than 28.00 N/mm 2 and minimum 23.00 N/mm 2 (Table-1) for 10% and 17.five percent grain husk correspondingly. For RHA mixed mortar samples, surface strength elevated marginally from 16.67 N/mm 2 to 17.33 N/mm 2 (3.96%) which further demonstrated a low worth of 16.67 N/mm 2 for mortar cubes with 17.5% RHA. For concrete samples, strength elevated up to 10% RHA and then it began decreasing as well as the mortar samples same trend ongoing up to 15% RHA. Construed in the graph the strength is elevated quickly from 7.5% to fifteenPercent also it starts decreasing with rise in number of admixture. The reference mortar cube is getting strength of N/mm –

Surface Moisture Test Results

Surface moisture for concrete cubes was 17.31% which elevated to 17.97% for 7.5% RHA content. For greater % of RHA, it demonstrated a low trend with minimum value 17.2% for 17.5% RHA. For RHA mixed mortar cubes, maximum value was 17.32% with 10% RHA which further decreased to fifteen.89% for 17.5% RHA.

Figure 2 (a): Variation of NDT Qualities of Mortar Cubes

Pulse Velocity Test

Pulse velocity was observed 3258 m/sec. in normal concrete cubes which elevated to maximum 3736 m/sec. in 15.00% RHA mixed cubes. Rise in pulse velocity was 6.78%, 10.25%, 12.68%,14.67% and 13.51% for corresponding RHA 7.5%, 10%, 12.5%, 15%, and 17.5% correspondingly.

Elastic modulus elevated from three.83 GN/m 2 to some maximum 5.97 GN/m 2 (55.87%) for 12.5% RHA mixed samples.

Figure 2 (b): Variation in Compressive Strength, Rebound Hammer
Strength and Surface Moisture

Porosity

For nominal mix M20 grade concrete cubes, water absorption coefficient was discovered 1.19 Kg/m 2 /” min. In RHA mixed concrete samples, water absorption coefficients exhibited decreasing trend low of just one.34 (29.84%) for 12.5% of RHA however the same elevated with greater number of RHA. For optimum proportion of RHA (17.5%) it had been found 1.63 Kg/m 2 /” min, 15.18% greater compared to minimum value.

Figure 2 (c): Variation in Compressive Strength, Rebound Hammer
Strength and Surface Moisture

Conclusion

In nominal mix M20 grade concrete and 1:4 cement mortar RHA was added being an admixture from 7.50% to 17.50% by having an uniform variation of two.5%. During destructive test, compressive strength of mortar cubes and rebound hammer strength of concrete samples found elevated with maximum variation of 67.85% and 39.65% for 10% RHA. Maximum variations of elastic modulus were 55.87% adopted by 27.94% for 12.50% and 10% RHA mixed samples. Compressive strength of concrete samples demonstrated maximum increase 3.08% between RHA 7.50% to 10.00% which decreased further for greater number of RHA.

Decrease in water absorption, from results acquired from 6 tests concrete and three tests on mortar samples, it’s observed that as much as 10% RHA with concrete and mortar enhances all qualities (Figures 2a to c) which is observed that 12.5% of Grain Husk Ash by mass of cement because the optimum doses to be included concrete manufacture of M20 specially when the husk is burnt under field condition to make use of the readily available and occasional cost sources for betterment of concrete structure regarding economy, durability and strength. So best relevant number of grain husk ash according to field condition 10.00% for optimal durability and strength.

References

  • Bronzeoak Limited, Grain Husk Ash Market Study, ETSU U/00/00061/Repetition DTI/Pub URN 03/668, 2003.
  • Satish Chandra, Spend utilized in concrete manufacturing, William Andrew Corporation. Norwich, NY 13815, 2002.
  • Hwang, C. L. and Wu, D. S. Qualities of Cement Paste That contains Grain Husk Ash, ACI SP-114, 1989.
  • Anderson,L.L. and Tillman D.A. Fuels from waste. Academic Press Corporation. New You are able to, U.S.A, 1978.
  • E. B. Oyetola and M. Abdullahi, Using Grain Husk Ash in Low–Cost Sandcrete Block Production, Department of Civil Engineering, Federal College of Technology, P.M.B. 65, Minna, Nigeria, June 2006.

NBMCW October 2010

Sudisht Mishra. Faculty Civil Engineer. Deptt NERIST, Itanagar, Prof (Dr.) S. V. Deodhar. Principal, SSVPS BSD College of Engineering, Dhule.

Introduction

Workability, strength, and sturdiness are three basics qualities of concrete. Quantity of helpful internal work essential to overcome the interior friction to create full compaction known as as Workability. Size, shape, surface texture and grading of aggregates, water-cement ratio, utilization of admixtures and blend proportion are essential factors affecting workability. Strength would be to bear the preferred stresses inside the allowable factor of safety in expected exposure condition. The factor influencing the force are: quality of cement, water-cement ratio, grading of aggregates, amount of compaction, efficiency of curing, curing temperature, age during the time of testing, impact and fatigue. Durability is nutrition of shape, size and strength potential to deal with exposure conditions, disintegration and putting on under adverse conditions. Variation in concrete production, loading conditions operating existence and subsequent attack through the atmosphere factors are primary failing factor of concrete. Correctly compacted and cured concrete utilized in RCC remains substantially water-tight and sturdy till capillary pores and micro-cracks within the interior are interconnected to create pathways as much as surface.

Durability is principally affected by ecological exposure condition, freezing – thawing, contact to aggressive chemicals, type and excellence of constituent materials, water-cement ratio, workability, size and shape from the member, amount of compaction, efficiency of curing, effectiveness of canopy concrete, porosity and permeability. During service existence of structures, transmission water and aggressive chemicals, carbonation, chloride ingress, leaching, sulphate attack, alkali-silica reaction and freezing-thawing are resulting degeneration. Loading and weathering inter link voids and micro-cracks contained in transition zone and network of same micro cracks will get linked to cracks on concrete surface which supplies primary mechanism from the fluid transport to interior of concrete. Subsequent increase of penetrability results in easy ingress water, oxygen, co2 and acidic ions etc into concrete resulting cracking, spalling, loss at mass, strength and stiffness.

Low permeability is essential to durability which is controlled by factors such as water-cement ratio, amount of hydration, curing, entrapped air voids, micro cracks because of loading and cyclic contact with thermal variations. Admixture improves workability, compactibility, strength, impermeability, potential to deal with chemical attack, corrosion of reinforcement and freezing – thawing etc. and as a result to durability. With this study durability is construed when it comes to porosity, moisture movement, surface strength, ultra seem pulse velocity and elasticity modulus of concrete. Better use of Grain Husk Ash (RHA), acquired by open field burning method, is made the decision for improving workability, durability and strength of concrete.

Grain Husk Ash

RHA, created after burning of Grain husks (RH) has high reactivity and pozzolanic property. Indian Standard code of practice for plain and reinforced concrete, IS 456- 2000, recommends utilization of RHA in concrete but doesn’t specify quantities. Chemical compositions of RHA may take a hit because of burning process and temperature. Silica content within the ash increases with greater the burning temperature. According to study by Houston, D. F. (1972) RHA created by burning grain husk between 600 and 700°C temperatures for just two hrs, contains 90-95% SiO2. 1-3% K2 O and 5% unburnt carbon. Under controlled burning symptom in industrial furnace, conducted by Mehta, PKay. (1992), RHA contains silica in amorphous and highly cellular form, with 50-1000 m 2 /g area. So utilization of RHA with cement improves workability and stability, reduces heat evolution, thermal cracking and plastic shrinkage. This increases strength development, impermeability and sturdiness by strengthening transition zone, modifying the pore-structure, blocking the big voids within the hydrated cement paste through pozzolanic reaction. RHA minimizes alkali-aggregate reaction, reduces expansion, refines pore structure and hinders diffusion of alkali ions towards the the surface of aggregate by micro porous structure.

Portland cement contains 60 to 65% CaO and, upon hydration, a substantial part of lime is released as free Ca(OH)2. that is mainly accountable for poor people performance of Portland cement concretes in acidic environments. Silica contained in the RHA combines using the calcium hydroxide and results excellent resistance from the material to acidic environments. RHA replacing 10% Portland cement resists chloride transmission, improves capillary suction and faster chloride diffusivity.

Pozzolanic result of RHA consumes Ca(OH)2 contained in a hydrated Portland cement paste, reduces prone to acidity attack and improves potential to deal with chloride transmission. This reduces large pores and porosity resulting really low permeability. The pozzolanic and cementitious reaction connected with RHA cuts down on the free lime contained in the cement paste, lessens the permeability from the system, improves overall potential to deal with CO2 attack and enhances potential to deal with corrosion of steel in concrete. Highly micro porous structure RHA mixed concrete provides escape pathways for that freezing water within the concrete, relieving internal stresses, reducing micro cracking and improving freeze-thaw resistance.

Non Destructive Tests (NDT)

NDT, systems needed for assessing strength operating feature, is understood to be an evaluation which doesn’t impair the intended performance from the element or member under analysis, transported out onsite, with ability to look for the durability and strength of critical constructions with no damage to.

For performing ND Tests, Rebound hammer, Protimeter-moisture measurement system, Porositester and pulse Ultrasound Non-Destructive Indicating Tester (PUNDIT) equipment are utilized.

Rebound hammer test is carried out to evaluate the relative strength of concrete in line with the hardness at or near its uncovered surface. Concrete Rebound Test Hammer is really a traditional instrument employed for the non-destructive testing of hardened concrete. This gives a simple and quick test way of acquiring an instantaneous symbol of concrete strength in a variety of areas of a structure. Knob of the instrument is stored verticle with respect towards the surface (i.e. ninety degree towards the surface) for measurement and it is push pressed in the bottom towards the top of concrete, hammer like seem is created. The button near the foot of the instrument is pressed to lock the indicator and studying is taken.

The top moisture is usually not seen to clean and restoring the dwelling after damage from storms, floods or fires. For uncovered or unseen structural damage, the undetected moisture damages strength, durability and reliability. The Protimeter Moisture Measurement Product is a effective and versatile instrument for calculating and diagnosing surface moisture in structures. This instrument directly displays moisture content (%) together with three conditions of fabric like DRY, WET and RISK condition. For implementing Protimeter operational modes are selected and knowledge is presented on the large, back lit live view screen display. Radio stations frequency sensor lies to ensure that many moisture readings is taken rapidly and simply.

Porositester contains of three glass tube accustomed to appraise the water transmission in concrete at atmospheric pressure. Tubes are fixed with vacuum plate and vacuum pump with no subsequent cleaning. Rubber seal placed within the tube supplies a defined contact the surface of dia 25 mm vertical or horizontal. Compressible seals on suction plate and tube permit secure fixing and to uneven surfaces. Current supply is supplied from the 12 V rechargeable battery. Vacuum plate is pressed from the faade having a wet sponge, motor is positioned on adhesion from the plate is checked. Test tubes are put underneath the clip and guaranteed firmly with screws. Test tubes are full of water to the zero mark and again refilled following the descent from the level by one or two ml and readings of volume of permeated water are noted lower for 15 minute test time. As reported by the manual of apparatus, water absorption coefficient A is calculated by utilizing following formula:

X=Amount (level) water permeated in ml.

d= Dia. of test tube in mm.

t= Duration of transmission within a few minutes.

Figure 1: Porositester

Figure 1 shows the Porositester pointed out above Pundit is really a highly reliable equipment for ultrasound pulse velocity teshon concrete. Pundit plus can be used to find out pulse velocity, (UPV) modulus of elasticity, tooth decay and cracks contained in the concrete. Devices are ruggedly designed for on-site reliability for straightforward, fast operation with integral RS232 interface, auto memory store for readings, large Liquid crystal display with exterior or electric batteries supply. The setup parameters are defined for that preferred mode of operation and particular values are displayed.

Workplan

Purpose of the work would be to read the results of Grain Husk Ash being an admixture on workability, strength, reliability of cement concrete and cement mortar. In line with the above, optimum dose of RHA is decided to boost the preferred qualities of concrete without causing any adverse result on other qualities.

Grain Husk from local Grain Mills was burnt completely in open field condition and sieved with 150 micron IS sieve. Grain Husk Ash percentage was gradual elevated from 7.5%, 10.%, 12.5%, 15.% and 17.5%. M20 grade nominal mix concrete (1. 1.5. 3) and cement mortar of proportion (1. 4). Coarse aggregate of 20 mm graded nominal size, river sand zone III type and 53 grades Pozzolana Portland Cement (PPC) were utilised with this work. For slump values 15 mm to 35 mm and compaction factor .85 to .90, water cement ratio for plain and RHA mixed concrete was .50 and .575 correspondingly. For casting concrete and mortar cubes, 150 mm steel cube moulds and 70.7 mm steel cube moulds were utilised. Each set Contained Six examples of plain concrete and 6 of RHA mixed. After 24 hrs of casting, samples were opened up and stored under plain tap water curing for 4 weeks. Later destructive and non-destructive tests were transported on group of three separate cubes and average values taken with this study.

Test Results
Compressive Strength

Compressive strength for RHA mixed concrete samples elevated up to 12.5% of RHA and decreased for greater % of RHA. Greatest strength was discovered 30.3 N/mm 2 adopted by 30.07 N/mm 2 for RHA composition 10.00% and 12.5% correspondingly. Compared to normal M20 mix samples, compressive strength decreased by 12.94% and 19.17% for 15.00% and 17.5% of RHA mixed concrete samples. Between RHA compositions 10% and 12.5%, compressive strength elevated very marginally (.80%) whereas same return was greatest (3.08%) between RHA compositions 7.50% and 10.00%.

Compressive strength of ordinary mortar cubes was 10.39 N/mm 2 and same elevated to 16.43 N/mm 2 and 17.44 N/mm 2 for RHA composition 7.5% and 10.00% correspondingly. For greater proportion of RHA, 12.50%, 15.00% and 17.50%, compressive strength decreased to 12.74 N/mm 2. 10.73 N/mm 2 and seven.71 N/mm 2 correspondingly. Maximum rise in strength was 67.85% adopted by 58.13% for 10.00% and seven.50% RHA composition correspondingly.

Rebound Hammer Test

Surface strength of M20 grade concrete cube was 20.05 N/mm 2. For RHA mixed samples, same values elevated to no more than 28.00 N/mm 2 and minimum 23.00 N/mm 2 (Table-1) for 10% and 17.five percent grain husk correspondingly. For RHA mixed mortar samples, surface strength elevated marginally from 16.67 N/mm 2 to 17.33 N/mm 2 (3.96%) which further demonstrated a low worth of 16.67 N/mm 2 for mortar cubes with 17.5% RHA. For concrete samples, strength elevated up to 10% RHA and then it began decreasing as well as the mortar samples same trend ongoing up to 15% RHA. Construed in the graph the strength is elevated quickly from 7.5% to fifteenPercent also it starts decreasing with rise in number of admixture. The reference mortar cube is getting strength of N/mm –

Surface Moisture Test Results

Surface moisture for concrete cubes was 17.31% which elevated to 17.97% for 7.5% RHA content. For greater % of RHA, it demonstrated a low trend with minimum value 17.2% for 17.5% RHA. For RHA mixed mortar cubes, maximum value was 17.32% with 10% RHA which further decreased to fifteen.89% for 17.5% RHA.

Figure 2 (a): Variation of NDT Qualities of Mortar Cubes

Pulse Velocity Test

Pulse velocity was observed 3258 m/sec. in normal concrete cubes which elevated to maximum 3736 m/sec. in 15.00% RHA mixed cubes. Rise in pulse velocity was 6.78%, 10.25%, 12.68%,14.67% and 13.51% for corresponding RHA 7.5%, 10%, 12.5%, 15%, and 17.5% correspondingly.

Elastic modulus elevated from three.83 GN/m 2 to some maximum 5.97 GN/m 2 (55.87%) for 12.5% RHA mixed samples.

Figure 2 (b): Variation in Compressive Strength, Rebound Hammer
Strength and Surface Moisture

Porosity

For nominal mix M20 grade concrete cubes, water absorption coefficient was discovered 1.19 Kg/m 2 /” min. In RHA mixed concrete samples, water absorption coefficients exhibited decreasing trend low of just one.34 (29.84%) for 12.5% of RHA however the same elevated with greater number of RHA. For optimum proportion of RHA (17.5%) it had been found 1.63 Kg/m 2 /” min, 15.18% greater compared to minimum value.

Figure 2 (c): Variation in Compressive Strength, Rebound Hammer
Strength and Surface Moisture

Conclusion

In nominal mix M20 grade concrete and 1:4 cement mortar RHA was added being an admixture from 7.50% to 17.50% by having an uniform variation of two.5%. During destructive test, compressive strength of mortar cubes and rebound hammer strength of concrete samples found elevated with maximum variation of 67.85% and 39.65% for 10% RHA. Maximum variations of elastic modulus were 55.87% adopted by 27.94% for 12.50% and 10% RHA mixed samples. Compressive strength of concrete samples demonstrated maximum increase 3.08% between RHA 7.50% to 10.00% which decreased further for greater number of RHA.

Decrease in water absorption, from results acquired from 6 tests concrete and three tests on mortar samples, it’s observed that as much as 10% RHA with concrete and mortar enhances all qualities (Figures 2a to c) which is observed that 12.5% of Grain Husk Ash by mass of cement because the optimum doses to be included concrete manufacture of M20 specially when the husk is burnt under field condition to make use of the readily available and occasional cost sources for betterment of concrete structure regarding economy, durability and strength. So best relevant number of grain husk ash according to field condition 10.00% for optimal durability and strength.

References

  • Bronzeoak Limited, Grain Husk Ash Market Study, ETSU U/00/00061/Repetition DTI/Pub URN 03/668, 2003.
  • Satish Chandra, Spend utilized in concrete manufacturing, William Andrew Corporation. Norwich, NY 13815, 2002.
  • Hwang, C. L. and Wu, D. S. Qualities of Cement Paste That contains Grain Husk Ash, ACI SP-114, 1989.
  • Anderson,L.L. and Tillman D.A. Fuels from waste. Academic Press Corporation. New You are able to, U.S.A, 1978.
  • E. B. Oyetola and M. Abdullahi, Using Grain Husk Ash in Low–Cost Sandcrete Block Production, Department of Civil Engineering, Federal College of Technology, P.M.B. 65, Minna, Nigeria, June 2006.

NBMCW October 2010


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