Self-Compacting Concrete with Recycled Traditional Roof Tile Powder

Bad reinforcement concrete works could generate building failures after earthquake. Concrete pouring and compacting on structural element with dense reinforcement and beam column joint are difficult. Suitable solution on this problem is the use of self-compacting concrete that has flow-ability, filling-ability, and passing-ability. Traditional roof tile waste is available in Indonesian villages. The use of traditional roof tile powder in self-compacting concrete is an effort to recycle waste and new development in environmental friendly concrete material technology. This research tends to understanding contribution of traditional roof tile powder in development of workability and strength of self-compacting concrete. On this research, self compacting concretes are designed as follows: 1) water-powder ratio (w/p) is designed with 0.35, 0.32, and 0.29; 2) maximum dimension of coarse aggregate is limited by 15 and 20 mm; 3) dosages of traditional roof tile powder are 0%,10%,20%, and 30% from powder weight; 4) dosage of silica fume sets to be 5% for all trial mixes; 5) super-plasticizer is added with dosage of 0.5%, 1.0%, 1.2% and 1.5% from powder weight to achieve flow characteristic of self compacting concrete; 5) aggregates are washed before mixing. Indonesian standard (SNI 03- 2834-2000) combined with simple mix design Okamura are used to calculate the compositions of self-compacting concrete. Test on fresh concrete is slump spread for all trial mixes. The mix that has the largest slump spread is tested with V-funnel and L-shaped box. Specimens of cylinder with diameter of 10 cm and height of 20 cm are used in this research to determine the compressive strength and split-tensile strength. Maximum diameter of slump spread could achieve 65 cm. Duration in V-funnel test is 14.6 second. In L-shaped box, duration to reach 40 cm and to reach box-end are 45 and 65 second, respectively. Blocking/passing ratio (H2/H1) is 4.5/32. Optimum dosage of traditional roof tile powder is 20% at w/p of 0.35 and dosage of super-plasticizer of 1% that has compressive strength of 44.11 MPa and split-tensile strength of 3.25 MPa. Washing aggregate before mixing could increase workability performance and increase compressive and split-tensile strength of 17.06% and 42.37%. Coarse aggregate with maximum dimension of 20 mm has compressive strength of 51.05 MPa. Optimum w/p is 0.32 and optimum dosage of super-plasticizer is 1.5% at dosage of traditional roof tile powder of 20%, dosage of silica fume of 5%, and proportion of coarse aggregate of 45% that has the largest compressive strength of 67.72 MPa.