STUDY ON WORKABILITY CHARACTERISTICS OF SELF-COMPACTING CONCRETE AT DIFFERENT PROPORTIONS OF CLASS-F FLY ASH AND GGBS B.Bhavani 1,C. Krishnama Raju 2, Talha Zaid 3 1 Post-Graduate Student, 2 Associate Professor, 3 Assistant Professor,Department of Civil Engineering, Rajeev Gandhi Memorial College of Engineering and Technology, Nandal ABSTRACT This paper investigates the study of workability properties of Self-compacting concrete with Class-F Fly ash and Ground granulated blast furnace slag(ggbs) at different proportions. Self-compacting concrete is a sort of concrete which flows under its own weight without any vibration. The main aim of this study is to use mineral admixtures like Fly ash and Ground granulated blast furnace slag(ggbs) to compare the fresh properties governed by slump flow,t50,j-ring,v-funnel,l-box tests. The mix design for Self-compacting concrete (SCC) is adopted by the Nan-Su et.al method (2001).The percentage of powder proportions other than cement are established for M25 grade concrete as 100%GGBS, 80%GGBS&20%FA,60%GGBS& 40%FA, 40%GGBS&60%FA,20%GGBS &80%FA,100%FA in the Nan-Su mix design with a W/P ratio of 0.425. Super plasticizer CONPLAST SP430 it is a super plasticising admixture based on selected sulponated naphthalene polymers is used to maintain workability. The Fresh properties of Self-compacting concrete have been carried out as per EFNARC Guidelines. Keywords: EFNARC, Fly ash, Ground granulated blast furnace slag (GGBS),J-Ring test,l-box test,slump Flow test,t50 test,v-funnel test I. INTRODUCTION Concrete is a adaptable material extensively used in construction applications throughout the world. Properly placed and cured concrete shows excellent compressive-force-resisting characteristics and engineers rely on it to perform in numerous situations. The growth of concrete in special architectural configurations and closely spaced reinforcing bars have made it very important to produce concrete that ensures proper filling ability, good structural performance and sufficient durability.to help to lighten these concerns, Japanese researchers in the late 1980 s developed a concrete mixture that collapsed under its own weight, thus filling around and enclose reinforcing steel without any mechanical consolidation. Self compacting concrete (SCC) is a high performance, better and more dependable and uniform quality concrete which doesn t require any vibration. SCC was first acknowledged by Japan in the late 1980 s and by the 1990 s Japan has developed and used SCC that doesn t not require vibration to attain full compaction. SCC consists basically of the same constituents as a normally vibrated concrete. However, there is a clear difference 192 P a g e
in the concrete composition. It requires a higher amount of ultra fine materials and the integration of chemical admixtures, mainly effective high range water reducers. Current studies in SCC, which are being conducted in many countries, can be divided into the following categories: (i) Use of rheometers to obtain data about flow behaviour of cement paste and concrete, (ii) Mixture proportioning methods for SCC, (iii) Characterization of SCC using laboratory test methods, (iv) Durability and hardened properties of SCC and their comparison with normal concrete, and (v) Construction issues related to SCC. II. EXPERIMENTAL INVESTIGATION Materials Self compacting concrete was made of cement, Fine aggregate, Coarse aggregate, water, Class-F Fly ash and Ground granulated blast furnace (GGBS) as mineral admixtures and Super plasticizer as chemical admixture. 2.1 Cement: Ordinary Portland cement, 53 grade, cement has been tested for various proportions as per IS: 4031-1988 and found to be conforming to various specifications of IS: 12269-1987. By conducting different experiments on the cement (Ordinary Portland Cement (OPC) of 53 grade) following results are tabulated. Table-1 Test Results On Cement (IS 12269-1987) Properties Results obtained Range Setting time Initial 129 min >30 min Final 225 min <600 min Specific Gravity 3.16 3.0 3.25 Soundness of Cement 0.5mm <10 mm Fineness 2% <10% Standard Consistency 31% - 2.2 Fine aggregate : : Locally available sand having specific gravity of 2.64 conforming to IS: 383-1970. Table-2 Test Results On Fine aggregate (IS 383-1970) Properties Results obtained Range Specific Gravity 2.64 2.5-3.0 Fineness Modulus Test 2.46 2.2-2.6 Bulking Of sand 21% - 2.3 Coarse aggregate: Locally available crushed stones graded of nominal size of 12.5-20mm as per IS: 383-1970. 193 P a g e
Table-3 Test Results On Coarse aggregate (IS 383-1970) Properties Results obtained Range Flakiness Index 21.52% <35% (BS 882-1992) Shape Tests <40% (BS 882-1992) Elongation Index 26.32% Aggregate Impact Test 16.66% <35% Los Angeles Abrasion Test 10.34% <40% Specific Gravity Test 2.73 2.6-2.8 Aggregate Crushing Value 18.32% <45% 2.4 Fly ash: It is a finely divided residue resulting from the combustion of powdered coal and transported by the flue gases and collected by electro-static precipitator. In the chemical properties of Fly ash CaO content is less than 20% hence it is said to Class-F fly ash, confined as per IS 3812:2000. Table-4 Chemical Properties of Fly Ash Properties Test results Chemical requirement as per IS 3812-1:2003 Moisture 0.20% - Loss on ignition 4.00% 5.0 Max Sio2+Al2o3+Fe2o3 89.82% 70.0 Min Silicon dioxide(sio2) 60.70% 35.0 Min Reactive silica 52.35% 20.0 Min Magnesium Oxide(Mgo) 0.64% 5.0 Max CaO 9.02% <20% for Class-F fly ash >20% for Class-C fly ash Total Sulphur as Sulphur Trioxide(So3) 0.18% 3.0 Max Available Alkalis as Sodium Oxide(Na2o) 0.34% 1.5 Max Total Chlorides <0.01% 0.05 Max Specific gravity 2.2-2.5 Ground granulated blast-furnace slag (GGBS) : Ground granulated blast-furnace slag is a non-metallic powder consisting of silicates and aluminates of calcium and other bases. The chemical composition of blast furnace slag is similar to that of cement clinker. The quality of slag is governed by IS 12089-1987 and BS 9966. 194 P a g e
Packing Factor Coarse aggregate Fine aggregate W/P ratio Cement SP dosage% of powder SP Content Fly ash GGBS Water (lt/m 3 ) Table-5 Chemical Properties of GGBS Approximate Chemical Properties Test results requirements as per IS 12089-1987 and BS 9966 Moisture 0.15 % - Loss on ignition 1.56 % - Cao+MgO+SiO2 78.56 % - Silicon dioxide(sio2) 34.28 % 30-38 Calcium oxide(cao) 37.08 % 30-45 Magnesium Oxide(Mgo) 7.20 % 4.0-17.0 Glass content 92.60 % 85-98 Aluminum oxide(al2o3) 18.02 % 15-25 Chloride content 0.007 % - Specific gravity 2.89-2.6 Chemical admixtures: Super plasticizers (High range water reducers) : It is chemical compound used to increase the workability, without using any additional water; these admixtures allow 12-30% water reduction. In this investigation we have used Conplast SP430, it is a chloride free superplasticising admixture based on selected sulponated naphthalene polymers compiles with BS 5075 part 3 and with ASTM C494 as Type A and Type F. Table-6 Properties of Super plasticizer Appearance Brown liquid Specific gravity Typically 1.20 at 20 C III. MIX PROPORTIONS Chloride content Nil to BS 5075 The trial mix design Self compacting concrete(scc) with different proportions of Class-F fly ash and Ground granulated (GGBS) based on Nan-Su et.al (2001) method. Table-7 Mix proportions w.r.t to Nan su et.al mix design Mix proportions Powder proporti ons other than cement in Nan % of cement in total cement itious materi al 195 P a g e
su mix design 1.14 787 865 100GGB S 35.8% 0.42 5 1.14 787 865 80G&20 37.4% 0.42 F 5 1.14 787 865 60G&40 38.8% 0.42 F 5 1.14 787 865 40G&60 40.25 0.42 F % 5 1.14 787 865 20G&80 41.421 0.42 F % 5 1.14 787 865 100FA 42.6% 0.42 5 230 1.0 2.3-411.46 270.32 230 0.9 2.25 76.81 307.25 258.75 8 4 230 0.9 2.20 145.0 217.53 249.65 6 8 2 5 230 0.9 2.16 204.8 136.54 240.69 4 2 2 8 9 230 0.9 2.11 260.2 65.052 234.86 2 6 1 230 0.9 2.07 309.3-227.19 8 IV. RESULTS AND DISCUSSION Concrete can be classified as Self-compacting concrete if it has the following characteristics: Filling ability Passing ability Segregation Resistance Tests on fresh properties 4.1 Slump Flow Test: Slump-flow value describes the filling ability of a fresh mix in unconfined conditions. It is a sensitive test that will normally be specified for all SCC, as the primary check that the fresh concrete consistence meets the specification.the minimum value of slump is to be 650 mm and the maximum value 800 mm for a fresh SCC. The slump values for different proportions according to the specified ranges are shown in Fig.1 Table-8 Slump Flow with Class-F fly ash and GGBS Mix proportions Slump flow(mm) (%) 100G 656 80G20F 668 60G40F 671 40G60F 667 20G80F 669 100F 668 196 P a g e
Fig 1 Slump Flow with Class-F fly ash and GGBS 4.2 J-Ring test: The J-ring test is used to determine the passing ability of the SCC. The diameter of the ring of vertical bars is 300 mm, and the height 100 mm.after the test, the difference in height between the concrete inside and that just outside the J-ring is measured. This is an indication of passing ability, or the degree to which the passage of concrete through the bars is restricted. The J-Ring values for different proportions according to the specified ranges are shown in Fig.2. Table-9 J-Ring Test with Class-F fly ash and GGBS Mix proportions (%) J-Ring test(mm) 100G 1.460 80G20F 1.180 60G40F 1.152 40G60F 1.200 20G80F 1.151 100F 1.147 197 P a g e
Fig 2 J-Ring Test with Class-F fly ash and GGBS 4.3 L-Box test : This test is used to evaluate the fluidity of Self compacting concrete and its ability to pass through the steel bars. The basic test result is the 'blocking ratio' h2/h1. It is the ratio between the height of the concrete surface in the vertical column part of the apparatus (h1) and the height of the concrete surface in the through at its far end (h2), after the passage through vertical reinforcing bars There are two additional marks on the horizontal trough at 200mm and 400mm from the sliding door. ratio between these two heights (h2/h1), which is usually 0.8-1.0. The L-Box results for different proportions according to the specified ranges are shown in Fig.3. Table-10 L-Box Test with Class-F fly ash and GGBS Mix proportions (%) L-Box test(mm) 100G 1.0 80G20F 0.971 60G40F 0.947 40G60F 0.95 20G80F 0.984 100F 0.994 198 P a g e
Fig 3 L-Box Test with Class-F fly ash and GGBS 4.4 V-Funnel Test: The version selected for evaluation in this study had a rectangular crossing tapering to a bottom opening of 65mm 75mm.The funnel was fitted with a trap door. A sample of fresh concrete of between 12 to 15 litres in volume is required. The V-funnel test is used to determine the deformability through restricted area. The V- Funnel results for different proportions according to the specified ranges are shown in Fig.4. Table-11 V-Funnel Test with Class-F fly ash and GGBS Mix proportions (%) V-Funnel test(sec) 100G 11.7 80G20F 9.4 60G40F 9.0 40G60F 9.2 20G80F 8.9 100F 9.0 199 P a g e
V-Funnel test(sec) 12 11 11.7 V-Funnel test(sec) 10 9 8 9.4 9 9.2 8.9 9 V-Funnel test(sec) 7 6 100GGBS80G&20F60G&40F40G&60F20G&80F Proportions of GGBS and Fly ash(%) 100FA Fig 4 V-Funnel Test with Class-F fly ash and GGBS 4.5 T50 Slump Flow Test: T50 slump flow test is same as the slump flow test. When the slump cone is lifted, start the stop watch and find the time taken for the concrete to reach 500 mm mark. This is called T50 time. Lower time indicates greater flowability.the typical range for T50 time is 2-5 sec. The T50 slump flow test results for different proportions according to the specified ranges are shown in Fig.5. Table-12 T50 slump flow Test with Class-F fly ash and GGBS Mix proportions (%) T50 slump flow test(sec) 100G 3.9 80G20F 4.2 60G40F 4.3 40G60F 4.3 20G80F 4.1 100F 4.0 200 P a g e
Fig 5 T50 Slump flow Test with Class-F fly ash and GGBS V. CONCLUSION The fresh properties such as Slump flow, J-ring test,v-funnel,l-box,t50 slump flow test values of SCC were satisfied as per EFNARC guidelines. With the addition of Fly ash to the concrete, it increases the workability of fresh concrete properties. Conplast SP430 has a substantial influence on fresh properties of SCC. SCC mix which incorporates GGBS requires high dosage of super plasticizer to produce satisfactory workability. The results shown that use of FA in GGBS concrete offsets the impact of GGBS has increasing the dosage of admixture in concrete to attain fresh concrete properties. Therefore by considering the fresh properties values as shown in Fig 1,2,3,4 and 5 we can say that SCC can be designed with Fly ash and GGBS with these proportions. REFERENCES [1] A.A.Maghsoudi, Sh.Mohamadpour,M.Maghsoudi. Mix design proportions of self compacting light weight concrete,2011. [2] Chung-ho huang, Shu-ken lin,chao-shun chang, How-ji chen. Mix proportions and mechanical proportions of concrete containing very high volume of Class-F fly ash, 2013. [3] Concrete Technology Theory and Practice Text book by M.S Shetty. [4] Dhiyaneshwaran.S, Ramanathan.P, Baskar.I, Venkatasubramani.R. Study on Durability Characteristics of Self-compacting Concrete with Fly ash, 2013. [5] EFNARC May 2005. European guidelines for self-compacting concrete, specification, production and use. [6] H. Okamura, Self Compacting High Performance Concrete Ferguson Lecture for 1996, Concrete International, Vol. 19, No. 7, 1997, pp. 50 54. 201 P a g e
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