An experimental study on strength development of concrete containing composite ash (Flay Ash-F & Rice husk ash)

An experimental study on strength development of concrete containing composite ash (Flay Ash-F & Rice husk ash)

International Journal of Engineering Research & Technology (IJERT)

ISSN: 2278-0181

Vol. 3 Issue 4, April – 2014

M. Sivakumar1 T. Manikandan2

1. Associate Prof, Department of Civil Engineering, PSNA College of Engineering and Technology, Dindigul 624622, Tamil Nadu

2. Assistant Prof , Department of Civil Engineering, PSNA College of Engineering and Technology, Dindigul

624622, Tamil Nadu

Abstract – In this Study, the detailed mechanical property was done to study the effect of partial replacement of cement by Fly Ash-Class F(FA) and Rice Husk Ash (RHA) in combine proportion started from 5% FA and 5% RHA mix together in concrete by replacement of cement with the gradual increase of RHA & FA. Last proportion was taken 20% FA and 20% RHA. The tests on hardened concrete were destructive in nature which includes compressive test and flexural strength at 7, 28 and 56 of curing as per IS: 516 1959, and split tensile strength on cylinder at 28 days of curing as per IS: 5816 1999. The work presented inthis paper reports the effects on the behavior of concrete produced from cement with combination of FA and RHA at different proportionson the mechanical properties of concrete.This study showed that strength increases with increasing amount of combined fly ash and rice husk ash up to an optimum value, beyond which strength starts todecrease with further addition of combined fly ash and rice husk ash. The optimum value of combined Fly ash(15%) and rice husk ash(15%) for the four test groups is about 30% of cement. FA&RHA/cement ratio is an important factor determining the efficiency of puzzolana.

1. INTRODUCTION

   Portland cement is widely used in construction in the last few decades. The production of cement involves very high temperature of 14000 to 15000C, the destruction of natural quarries to extract raw materials, the emission of the pollutant gases of CO2 and NO. The climate change due to global warming, one of the greatest environmental issues has become a major concern during the last decade. The global warming is caused by the emission of greenhouse gases, such as CO2, to the atmosphere by human activities. In the Indian scenario, among thegreenhouse gases CO2 contributes about 70% of global warming. The production of cement is increasing annually by 3% with present daytechnology, the production of 1 tonne of cement results in a CO2 emission of an average 0.8-0.9 tonnes.Fly ash is the byproduct of the combustion of pulverized coal and is collected by mechanical and electrostatic separators from the fuel gases of power plants where coal is used as a fuel. It is estimated that approximately 600 million tonnes of fly ash is available worldwide, but at present the current worldwide utilization rate of fly ash in concrete is about 10 per cent indicating that there is a potential for the use of much larger amounts

   of fly ash in concrete.The utilization of fly ash instead of dumping it as a waste material can be partly used on economic grounds as pozzolana for partial replacement of cement. And partly because of its beneficial effects such as lower water demand for similar workability, reduced bleeding, and lower evolution of heat. It has been used particularly in mass concrete applications and large volume placement to control expansion due to heat of hydration and also helps in reducing cracking at early ages.The utilization of rice husk ash (RHA) as cement replacement is a new trend in concrete technology. Besides, as far as the sustainability is concerned, it will also help to solve problems otherwise encountered in disposing of the wastes [Chandra, 1997]. Disposal of the husks is a big problem and open heap burning is not acceptable on environmental grounds, and so the majority ofhuskis currently going into landfill. The disposal of rice husks create environmental problem that leads to the idea of substituting RHA for silica in cement manufactured. The content of silica in the ash is about 92-97%.Research had shown that small amounts of inert filler have always been acceptable as cement replacement. RHA is very reach in silicon dioxide which makes it very reactive with lime due to its non-crystalline silica content and its specific surface. In addition of high strength and performance embedding high contents of rice husk ash resulted in high electrical resistivity.RHA with cellular microstructure and highly pozzolanic activity is formed. It contains high silica content in the form of non- crystalline or amorphous silica up to 95%. The utilization of fly ash instead of dumping it as a waste material can be partly used on economic grounds as pozzolana for partial replacement of cement and partly because of its beneficial effects such as lower water demand for similar workability, reduced bleeding, and lower evolution of heat. It has been used particularly in mass concrete applications and large volume placement to control expansion due to heat of hydration and also helps in reducing cracking at early ages.

2. MATERIALS AND PROPERTIES

   1. Cement

      In this project ordinary Portland cement of grade 53 is used.

   2. Fly Ash

      Fly ash produced from the burning of younger lignite or sub bituminous coal, in addition to having pozzolanic properties, also has some self-cementing properties. In the presence of water, Class F fly ash will hardenand gain strength over time. Class F fly ash generally contains less than 20% lime (CaO). Unlike Class C, Fly ash for the purpose of this investigation was obtained from Mettur ThermalPower Plant (MTSP) in Tamilnadu.

   3. Rice Husk Ash

      India produces about 218.2 million tonnes (18.90 million tones in Tamil nadu) of paddy every year. During milling of paddy about 78 % of weight is received as rice. Rest 22 % of the weight of paddy is received as husk. This husk is used as fuel in the rice mills to generate steam for the parboiling process. This husk contains about 75 % organic volatile matter and the balance 25 % of the weight of this husk is converted into ash during the firing process, is known as rice husk ash (RHA). This RHA in turn contains around 85 % – 90 % amorphous silica.

   4. Fine Aggregate

      Local clean river sand conforming to grading zone was used. The sand is sieved using 4.75 mm sieve to remove all the pebbles. Fine aggregate having a specific gravity of

      2.56 and fineness modulus of 2.75 and bulk density 1693 Kg/m3 was used.

   5. Coarse Aggregate

      Locally available well graded aggregates of normal size greater than 4.75 mm and less than 20 mm.Coarse aggregates having a specific gravity of 2.73, fineness modulus of 6.64 and bulk density 1527 Kg/m3 were used.

   6. Superplasticizer

      Sulphonatednapthaline formaldehyde (SNF) Manufactured by normal resinification of melamine formaldehyde.

   7. Physical Properties of Materials

      Property	Fly ash	RHA	Cem ent	Fine aggregate	Coarse aggregate
      Specifc gravity	1.77	1.96	3.10	2.56	2.70
      Finenes moduls	–	–	–	2.75	6.64
      Bulk density	1190 kg/m 3	496 kg/m3	–	1693 Kg/m3	1527/p> Kg/m3

      Table 1 – Physical Properties

   8. Chemical Characteristics

   Table 2 -Chemical Characteristics

   	Sio2	Fe2o3	Al2o3	Cao	Mgo	So3
   Cement	20.25	3.16	5.04	63.61	4.56	0.56
   Fly ash	56.65	4.29	27.35	2.19	0.57	0.45
   RHA	67.23	1.36	2.37	1.92	0.99	0.28

3. METHODS OF TESTING

   1. Compressive strength

      Compressive strength test is conducted on cubes of size 150mmX150mmX150mm. All specimens were tested in saturated surface dry condition, after wiping out the moisture. For each percentages and for normal three identical specimens were tested and is tested under a uniform rate of loading of 140 kg/cm2/min.

   2. Split Tensile Strength

      Split tensile strength test was conducted on fly ash and RHA blended concrete cylinders as per IS 5816-1999 after 28 days curing. For that cylinder of size 150mm dia and 300mm height were made and tested.

   3. Flexural Strength Of Concrete

      Compressive strength test is conducted on beam of size 500mmX10mmX10mm. All specimens were tested in saturated surface dry condition, after wiping out the moisture. For each percentages and for normal three identical specimens were tested and is tested under a uniform rate of loading of 140 kg/cm2/min.

      Result

      S.No.	% Replacement		Setting Time(min)
      	FA	RHA	Initial	Final
      1	–	–	70	285
      2	5	5	67	245
      3	10	10	65	220
      4	15	15	56	185
      5	20	20	49	265

      Table 4 -Initial & Final setting time

      F. pH test

      pH is defined as the negative logarithmic value of the Hydrogen ion (H+) concentration

      pH = -log [H+]

      when the pH is above 7 the solution is basic (alkaline) when the pH is below 7 the solution is acidic

      Result

      S.NO	% Replacement		pH Value
      	FA	RHA
      1	Water		7.2
      2	Pure cement Slurry		12
      3	5	5	11.98
      4	10	10	11.97
      5	15	15	11.95
      6	20	20	11.94

      Table 5 -pH Value

   4. Standard Consistency

      Consistency of standard cement paste is defined as that Consistency which will permit the vicat plunger 50mm long and having 10mm dia to Penetrate to a point 5mm to 7mm from bottom of the vicatmould.

      Result

      S.NO	% Replacement		Standard consistency (%)
      	FA	RHA
      1	–	–	31
      2	5	5	32
      3	10	10	34
      4	15	15	36
      5	20	20	36

      Table 3 -Standard consistency results

   5. Initial & Final Setting Time

   The change of cement paste from fluid to a rigid state may be referred to as setting. The gaining of strength of a set cement paste is known as hardening.

   1. Compressive strength of composite ash cement motor

      Compressive strength of cement indicates the compressive strength of cement mortar cubes (7.07cmx7.07cmx7.07cm) of 1:3 proportion, using standard sand as specified by IS :650 (1966) as fine aggregate , tested under compression Many other properties of mortar / concrete are related to compressive strength of cement, because cement is used in structure in the form of mortar or concrete.

      Result

      S.NO	% Replacement		Load Kg	Strength N/mm2
      	FA	RHA
      1	Control		16000	31.90
      2	5	5	12000	28.45
      3	10	10	13000	27.03
      4	15	15	12500	26.44
      5	20	20	11000	26.14

      Table 6-Compressive strength of composite ash cement motor

      40

      35

      30

      25

      20

      15

      10

      5

      0

   2. Soundness Of Cement

   28 Days

   Strength

   56 Days Strength

   Control 10

   7 Days

   Strength

   Compressive strength (N/mm2 )

   Soundness is nothing but volumetric change of the cement .Presents of chemicals such as CaO, MgO will react with the water present in the cement paste and it will increase the volume of cement paste while hardening.It may vary to each type of cement even for each batch. Soundness should not exceed 10mm for OP

   Result

   S.NO	% Replacement		Initial Reading (cm)	Final Reading (cm)	Soundness value(mm)
   	FA	RHA
   1	Control		1	1.1	2
   2	5	5	1.1	1.3	2
   3	10	10	1.1	1.4	3
   4	15	15	1.2	1.6	4
   5	20	20	1.6	2.0	5

   Table 7 – Soundness Of Cement

   20

   30

   40

   % REPLACEMENT OF FLY ASH & RHA

   Grape 1-Compressive Strength Of Composite Ash Concrete

   B. Split Tensile Strength Test Result

4. MIX PROPROTION (M20 GRADE CONCRETE)

   Water	Cement	Fine aggregate	Coarse aggregate
   191.6	383	536.16	1229.61
   0.5	1	1.45	3.30

5. RESULTS AND DISCUSSIONS

   1. Compressive Strength Of Composite Ash Concrete

      Table 7 -Compressive Strength Of Composite Ash Concrete

      S.NO	% Replacement		Compressive Strength (N/mm2 )
      	FA	RHA	7 Days	28 Days	56 Days
      1	Control		15.20	28.77	31.52
      2	5	5	14.50	30.52	34.17
      3	10	10	14.25	31.40	34.95
      4	15	15	14.20	33.13	36.71
      5	20	20	13.92	29.64	31.90

      Table shows the result of compressive strength of the blendedconcrete containing fly ash and RHA(composite ash). The strength is increasing up to 30% and there is a slight decrease in 40% replacement but it is also higher than the normal concrete strength. The incorporation of fly ash and RHA increases the strength of the concrete.

      Table 8Split Tensile Strength Test

      S.NO	% Replacement		Split tensile strength (KN/mm2)
      	FA	RHA	7 Days	28 Days	56 Days
      1	Control		2.90	3.30	3.80
      2	5	5	3.15	3.44	4.05
      3	10	10	3.20	3.70	4.15
      4	15	15	3.25	3.83	4.38
      5	20	20	2.95	3.75	4.00

      The split tensile strength of the blended concrete containing fly ash and RHA concrete after 7,28&56 days of curing are shown in table. It can be clearly seen that the splitting tensile strength value increases with fly ash and RHA content up to 30 % and the 40% is the optimal limit.

      1. Flexural Strength Test Result Result

         Table 9Flexural Strength Test Result

         S.NO	% Replacement		Flexural strength (KN/mm2)
         	FA	RHA	7 Days	28 Days	56 Days
         1	Control		4.2	5.8	5.9
         2	5	5	4.4	6.0	6.4
         3	10	10	4.7	6.1	6.4
         4	15	15	4.9	6.3	7.0
         5	20	20	4.5	5.9	6.2

         The flexural strength of the blended concrete containing fly ash and RHA concrete after 7, 28&56 days of curing are shown in table. It can be clearly seen that the splitting tensile strength value increases with fly ash and RHA content up to 30 % and the 30% is the optimal limit.

         International Journal of Engineering Research & Technology (IJERT)

         ISSN: 2278-0181

         3

         3.5

         6

         4

         7

         4.5

         8

         5

         Split Tensilestrength (KN/mm2 )

         Flexural Strength (KN/mm2)

         Vol. 3 Issue 4, April – 2014

         Control 10 20 30 40

         % Replacement of Fly Ash & RHA 7 Days Split Tensile Strength 28 Days Split Tensile Strength

         56 Days Split Tensile Strength 7 Days Flexural Strength

         28 Days Flexural Strength 56 Days Flexural Strength

         2.5

         Graph 2 – Split Tensile Strength &Flexural Strength Test

6. CONCLUSION

Fly ash and Rice husk ash is found to be superior supplementary materials. Fly ash F and Rice husk ash used inthis study is efficient as a pozzolanic material; Due to low specific gravity of ash whichleads to reduction in mass per unit volume, thus adding it reduces the dead load on the structure. Used of Fly ash and Ricehusk ash helps in reducing the environment pollution during the disposal of excess Fly ash and Rice husk ash. Cement iscostly material, so the partial replacements of these materials by Rice husk ash and Fly ash reduces the cost of concrete.Based on the results presented above, the following conclusions can be drawn:-

1. Compressive strength increases with the increase in the percentage of Fly ash and Rice Husk Ash up to replacement (15%FA and 15% RHA) of Cement in Concrete for different mix proportions.

2. The maximum 7, 28&56 days split tensile strength and flexural strength was obtained with combination ash of 30%( FA 15% and RHA 15%)

3. In the long run, our study has revealed the fact that composite ash (15%FA 15% RHA )may be treated as an finest creation in view of enhanced value of compressive strength, flexural and split tensile strength, superior corrosion inhabiting and desirable functionality.

4. The percentage of water cement ratio is reliant on quantity of ash used in concrete. Because ash is a highly porous material

REFERENCE

1. Rafat Siddique (2003), Properties of concreteincorporating high volumes of class F fly ash and san fibers, Concrete & Research journal, 34(1), pp 37-4

   5

2. Saravanarajamohan K, Jayabalan, P, and Rajaraman, A (2003), Studies on fly ash concrete composites, Proceeding of International Conference on Innovative World of Concrete, pp 102-105.

   3

   4

3. Goplakrishnan, S., Rajamane, N.P., Neelamegam, M., Peter, J.A. and Dattatreya, J.K (2001), Effect of Partial Replacement of Cement with Fly ash on the Strength and Durability of HPC, Indian. Concrete Journal, 75(5), pp 335-341.

4. Rafat Siddique Performance characteristics of high-volume Class F fly ash concrete Cement and Concrete Research 34 (2004)pp 487 4931. Compressive Strength and Durability Properties of Rice Husk Ash Concrete.

5. Ramasamy*Received February 11, 2009/Revised February 15, 2010/Accepted April 4, 2011,KSCE Journal of Civil Engineering (2012).

6. Maurice E. Ephraim, Godwin A. Akeke and Joseph O. Ukpata Compressive strength of concrete with rice husk ash as partial replacement of ordinary Portland cement-Scholarly Journal of Engineering Research Vol. 1(2), pp. 32-36, May 2012.

7. Dr. S.M.GUPTA,et.al CONCRETE Durabilitythrough High Volume Fly ash Concrete (HVFC) International Journal of Engineering Science and Technology Vol. 2(9), 2010, pp 4473-44777.

8. Abhilash Shukla Study of the Properties of Concrete by Partial Replacement of OrdinaryPortlandCement by Rice Husk Ash

   .International Journal of Earth Sciences and Engineering.

9. C Freedaet.alEffect of class F flyash as partial replacement with cementand fine aggregate in mortar, Indian Journel of Engineering & Material Sciences vol 17, april 2010. Pp140-144

10. C.S. Poon et.alA study on high strength concrete

    prepared with large volumes of low calcium fly ash Cement and Concrete Research 30 (2000) pp44-455

11. K. Ganesan , K. Rajagopal , K. Thangavel, Rice husk ash blended cement: Assessment of optimallevel of replaceent for strength and permeability properties of concrete. Construction and Building Materials 22 (2008) 16751683