An Experimental Investigation on Performance of Self Compacting Concrete with Partial Replacement of Cement by using Silica Fume and Rice Husk Ash

Transcription

1 An Experimental Investigation on Performance of Self Compacting Concrete with Partial Replacement of Cement by using Silica Fume and Rice Husk Ash 1 D.Mohan Kumar, 2 S.Pradeep 1 Lecturer, Department of Civil Engineering Veltech Polytechnic College Tamil Nadu, India 2 Assistant Professor (O.G), Department of Civil Engineering SRM University Tamil Nadu, India Abstract - Self compacting concrete (SCC) describes a concrete with the ability to compact itself only by means of its own weight without application of vibrator. SCC is a fluid mixture suitable for placing structures with congested reinforcement. Self-compacting concrete was first developed 1988 in order to achieve durable concrete structures. Since then, various investigations have been carried out and the concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mixdesign method and self compact-ability testing methods have been carried out to make the concrete the standard one. Self compacting concrete (SSC) is a concrete which compacts itself, there is no further compaction required for self compacting concrete. Making concrete structures without vibration have been done in the past. For examples, placement of concrete under water is done by the use of tremie without vibration. Mass concrete and shaft concrete can be successfully placed without vibration. In this phase, a study is conducted to evaluate mechanical properties of SCC prepared using Silica Fume and Rice Husk Ash.. Trials are conducted to assess the optimum percentage of SF and RHA for partial replacement of cement with various percentages of SF and RHA(, 10, 1and 20 by weight of cement) in 3:2 ratio. The Fresh concrete property of SCC such as Flow ability, Passing ability and Filling ability are tested using Slump Cone Test, L-Box Test, U- Funnel Test and V-Funnel Test. The Hardened properties of SCC ( Cubes, Prisms and Cylinders) are tested for Compressive Strength, 29 Authors: 1 D.Mohan Kumar, 2 S.Pradeep Flexural Strength and Split Tensile Strength. The compressive strength of SCC is increased as the replacement level of Silica Fume and Rice Husk Ash till 1. Beyond 1 replacement level, there is decrease in compressive strength. The optimum percentage of Silica Fume and Rice Husk Ash for partial replacement of cement in SCC during fresh property was found as 10 and during hardened property was found to be 1 from the test results. Keywords: self compacting concrete, silica fume and rice husk ash. 1. INTRODUCTION Self-compacting concrete was first developed 1988 in order to achieve durable concrete structures. Since then, various investigations have been carried out and the concrete has been used in practical structures in Japan, mainly by large construction companies. Investigations for establishing a rational mix-design method and self compact-ability testing methods have been carried out to make the concrete the standard one. Self compacting concrete (SSC) is a concrete which compacts itself, there is no further compaction required for self compacting concrete. Making concrete structures without vibration have been done in the past. For examples, placement of concrete under water is done by the use of tremie without vibration. Mass concrete and shaft concrete can be successfully placed without vibration. Rice husk is produced in the first step in the milling process when the husk is removed from the grain in the husking stage of the rice mill. Around 20 of the paddy weight is husk. In

2 2008 the world paddy production was 661 million tons and consequently 132 million tons of rice husk were also produced. While there are some uses for rice husk it is still often considered a waste product in the rice mill and therefore often either burned in the open or dumped on wasteland. Husk has a high calorific value and therefore can be used as a renewable fuel. Rice husk is difficult to ignite and it does not burn easily with open flame unless air is blown through the husk. It is highly resistant to moisture penetration and fungal decomposition. Husk therefore makes a good insulation material. Rice husk has low bulk density of only kg/m³, 14 kg/m³ when vibrated or 180kg/m³ in form of brickets or pellets. Rice husk has a high average calorific value of a 3410 kcal/kg and therefore is a good, renewable energy source. 1. Silica fume is a byproduct of producing silicon metal or ferrosilicon alloys. One of the most beneficial uses for silica fume is in concrete. Because of its chemical and physical properties, it is a very reactive pozzolan. Concrete containing silica fume can have very high strength and can be very durable. Silica fume is an ultrafine material with spherical particles less than 1 μm in diameter, the average being about 0.1 μm. This makes it approximately 100 times smaller than the average cement particle. The bulk density of silica fume depends on the degree of densification in the silo and varies from 130 (undensified) to 600 kg/m 3. The specific gravity of silica fume is generally in the range of 2.2 to 2.3. The specific surface area of silica fume can be measured with the BET methodor nitrogen adsorption method. It typically ranges from 1,000 to 30,000 m 2 /kg. 2. EXPERIMENTAL INVESTIGATIONS 2.1 MATERIALS Cement: In this experimental investigation Ordinary Portland cement of 3 grade is used The properties of Cement are as follows in table 2.1: TABLE 2.1. PROPERTIES OF CEMENT S.No Property Value 1. Specific Gravity Initial Setting 3minutes Time 3. Standard 34 Consistency 4. Fineness Fine Aggregate: Natural river sand with fraction passing through 4.7mm sieve and on 10µm sieve was used and tested as per IS: The important properties tested for the aggregate are given below in the table 2.2 TABLE 2.2 PROPERTIES OF FINE AGGREGATE S.No Property Value 1. Specific Gravity Fineness modulus Bulk density Kg/m Coarse Aggregate: crushed granite coarse aggregate of size 1.mm was used and tested as per IS: The important properties tested for coarse aggregates are given below in the table 2.3 TABLE2.3 PROPERTIES OF COARSE AGGREGATE S.No Property Value 1. Specific Gravity Bulk density Kg/m Silica Fume: Silica fume is an ultrafine material with spherical particles less than 1 μm in diameter, the average being about 0.1 μm. This makes it approximately 100 times smaller than the average cement particle. The properties of silica fume shown in the table 2.4 Figure 2.1 Silica Fume 30 Authors: 1 D.Mohan Kumar, 2 S.Pradeep

3 TABLE 2.4.PROPERTIES OF SILICA FUME S.No Properties and Value composition 1. Fineness (m 2 /kg) 1,000 to 3, Bulk density(kg/m3) 3. Specific gravity Silicon ( as > 8 SiO2). Aluminium ( as < 2 Al2O3) 6. Iron ( as Fe2O3) <1 7. Calcium ( as <1 CaO) 8. Magnesium ( as MgO) <1 9. Sodium ( as <1 Na2O) 10. Potassium ( as <1 K2O) 11. Chloride ( as Cl) < Loss on ignition () < Sulfate ( as < 0.3 SO4) 14. Free calcium < 1 oxide () 2.1. Rice Husk Ash: Rice husk is produced in the first step in the milling process when the husk is removed from the grain in the husking stage of the rice mill. Around 20 of the paddy weight is husk. In 2008 the world paddy production was 661 million tons and consequently 132 million tons of rice husk were also produced. While there are some uses for rice husk it is still often considered a waste product in the rice mill and therefore often either burned in the open or dumped on wasteland. Husk has a high calorific value and therefore can be used as a renewable fuel. Rice husk is difficult to ignite and it does not burn easily with open flame unless air is blown through the husk. It is highly resistant to 31 Authors: 1 D.Mohan Kumar, 2 S.Pradeep moisture penetration and fungal decomposition. Husk therefore makes a good insulation material. Rice husk has low bulk density of only kg/m³, 14 kg/m³ when vibrated or 180kg/m³ in form of brickets or pellets. Rice husk has a high average calorific value of a 3410 kcal/kg and therefore is a good, renewable energy source. The properties of rice husk ash is shown in the table 2. Figure 2.2 Rice husk ash TABLE 2.4. PROPERTIES OF RICE HUSK ASH S.No Properties and Value composition 1. Specific gravity Silicon ( as SiO2) Aluminium ( as 0.46 AlO3) 4. Iron ( as Fe2O3) Calcium ( as CaO) Magnesium ( as 0.44 MgO) 7. Sodium ( as Na2O) Potassium ( as K2O) Loss on ignition () MIX PROPORTIONS Mix design is carried out as per EFNARC Specifications which satisfied the workability test methods on concrete. The MIX PROPORTIONS of SCC as shown in the table 2..

4 TABLE 2.. MIX PROPORTIONS components Silica fume ricehuskash superplastizi cer CA Kg/m FA Kg/m Water kg/m Cement kg/m 3 Silicafume kg/m Ricehuskash kg/m superplastizi cer WORKABILITY TEST METHODS.1.1 Slump Flow Test: The slump flow is used to assess the horizontal free flow of Self Compacting Concrete in the absence of obstruction. This method is based on the test method for determining the slump..1.2 V-Funnel Test The equipment consists of a V shaped funnel. The described V funnel test is used to determine the filling ability (flow ability) of the concrete. The funnel is filledwith about 12 litres of concrete and the time taken for it to flow through the apparatus measured..1.3 L Box Test The test assesses the flow of the concrete and also extent to which it is subject to blocking by reinforcement U- Box Test A U-Box is a U-shaped box divided into two sections that are separated by a door. This test measures the ability of the concrete to flow through rebar and fill a form.. SPECIMEN PREPARATION Concrete cubes specimens (10 mm x 10 mm x10mm) for 4cubes were casted for computing compressive strength. The cylindrical specimens (diameter- 10 mm and length- 300 mm) for 30cylinders were casted to determine spilt tensile strength of concrete. The prism specimens (10 mm x 10 mm x10mm) for 30prisms were casted for computing flexural strength. All the specimens were cured for a period of 28 days before test. 6. RESULTS AND DISCUSSIONS After a detailed study we have obtained the following results for compression, split tensile strength and flexural strength. 6.1COMPRESSIVE STRENGTH Aim of this experimental test is to determine the maximum load carrying capacity of test specimens. Compression test is conducted on cubes of size 10 x 10 x 10 mm. Compressive strength test were carried out on the specimens at the age of 7,14 and 28 days. The compressive strength of the cement concrete is 33.29N/mm 2, 39.2 N/mm 2 and 37 N/mm 2 at 7 th, 14 th and 28 th day. The compressive strength of the 1 replacement level of SF and RHA in concrete attains the strength of 37.2 N/mm 2, N/mm 2 and N/mm 2 at 7 th, 14 th and 28 th day shown in the table 6.1 Figure 6.1 compressive testing machine 32 Authors: 1 D.Mohan Kumar, 2 S.Pradeep

5 TABLE 6.1 RESULTS FOR COMPRESSIVE STRENGTH 4.11 N/mm 2 and 4.92 N/mm 2 at 7 th and 28 th day shown in the table 6.2 Sl.No. of SF and RHA Compressive strength N/mm 2 7 th day 14 th day 28 th day days 14days 28days Figure 6.3 split tensile testing machine TABLE 6.2 RESULTS FOR SPLIT TENSILE STRENGTH Figure 6.2 compressive strength for various proportions of SF and RHA 6.2 SPLIT TENSILE STRENGTH S.NO of SF and RHA Split tensile strength N/mm 2 7 th day 28 th day The aim is determine the tensile strength of the SCC and PPFRSCC. The SCC specimen were tested in compression testing machine of capacity 2000 KN. Specimens, cylinder in shape, size of 10 mm diameter and height 300mm.The split tensile strength of the cement concrete is N/mm 2 and N/mm 2 at 7 th and 28 th day. The split tensile strength of the 1 replacement level of SF and RHA in concrete attains the strength of 33 Authors: 1 D.Mohan Kumar, 2 S.Pradeep days 28days Figure 6.4 split tensile strength for various proportions of SF and RHA 6.1 FLEXURAL STRENGTH The aim is to determine the flexural strength of the SCC and PPFRSCC. They were tested in Universal testing machine with capacity of 1000 tons. The specimens are prism shaped and size 00*100*100 mm 3. The flexural strength of the cement concrete is N/mm 2 and 2.40 N/mm 2 at 7 th and 28 th

6 day. The flexural strength of the 1 replacement level of SF and RHA in concrete attains the strength of 3.13 N/mm 2 and 4.21 N/mm 2 at 7 th and 28 th day shown in the table Figure 6.4 flexural testing machine TABLE 6.3 TEST RESULTS FOR FLEXURAL STRENGTH S.NO of SF and RHA Flexural strength N/mm 2 7 th day 28 th day days 28days Figure 6.4 flexural strength for various proportions of SF and RHA 34 Authors: 1 D.Mohan Kumar, 2 S.Pradeep CONCLUSIONS A suitable mix proportion using a cement replacement with SF and RHA at a level of 0,, 10, 1 and 20 has been obtained for SCC which satisfies the limiting values of filling ability and passing ability as suggested by EFNARC. The strength characters of SCC like compressive strength, flexural strength split strength with and without Silica Fume and Rice Husk Ash were studied. The compressive strength of the cement concrete is 33.29N/mm 2, 39.2 N/mm 2 and 37 N/mm 2 at 7 th, 14 th and 28 th day. The compressive strength of the 1 replacement level of SF and RHA in concrete attains the strength of 37.2 N/mm 2, N/mm 2 and N/mm 2 at 7 th, 14 th and 28 th day. The split tensile strength of the cement concrete is N/mm 2 and N/mm 2 at 7 th and 28 th day. The split tensile strength of the 1 replacement level of SF and RHA in concrete attains the strength of 4.11 N/mm 2 and 4.92 N/mm 2 at 7 th and 28 th day. The flexural strength of the cement concrete is N/mm 2 and 2.40 N/mm 2 at 7 th and 28 th day. The flexural strength of the 1 replacement level of SF and RHA in concrete attains the strength of 3.13 N/mm 2 and 4.21 N/mm 2 at 7 th and 28 th day. The optimum percentage of Silica Fume and Rice Husk Ash for partial replacement of cement in SCC during fresh property was found as 10. The partial replacement of cement by SF and RHA is feasible to obtain maximum Compressive strength of N/mm 2, Split tensile strength of 4.92 N/mm 2 and Flexural strength of 4.21 N/mm 2 at 28days on 1 of SF and RHA can be replaced in concrete to obtain the optimum strength. REFERENCES ACI 234 (96), Guide for the Use of Silica Fume in Concrete EFNARC (200), The European guide line for Self-compacting concrete

7 specification, production and use pp. 77. Farhad Aslani and Shami Nejadi (2012), Mechanical Properties of conventional and self-compacting concrete, An Analytical Study of Construction and Building Materials, Vol. 36, pp Dehwah H.A.F. (2012), Mechanical Properties of Self Compacting Concrete incorporating quarry dust powder, silica fume or flyash, Conctruction and Building Materials, Vol. 26, pp Hajimaokamura and masahiroouchi. (2003), Self-compacting concrete, Journal of Advanced Concrete Technology, Vol. 1, pp -1. Kennoucha S. and Zerizer A. (2013), Formulation and characterization of self compacting concrete with silica fume. Journal of Engineering and Technology Research, Vol., pp Ramanathan P. and Baskar L. (2013), Performance of Self-Compacting Concrete Containing Different Mineral Admixtures, Journal of Civil Engineering Vol.17, pp M.S.SHETTY. (200), Text book on Concrete Technology, S.Chand and Company Ltd. Rio Janeiro. (2012), Influence of Silica Fume on the Properties of Self- Compacting Concretes, International Conference on Engineering Optimization, Brazil Authors: 1 D.Mohan Kumar, 2 S.Pradeep