Effect of sodium silicate and silicafume solution on workability of recycled coarse aggregate in concrete

Abstract

Recycled coarse aggregate is known as suitable solution for reduce waste disposal cost in construction and enviromental sustainability. In this research, recycled coarse aggregate from concrete waste is used. Recycled coarse aggregate exhibits high absortion and mortar coating in surface. The replacement of recyclde coarse aggregate in range of 25 to 100% by weight in concrete mix proportion is considered. Sodium silicate solution 5% by weight is used for treatment recycled coarse aggregate. Then, silicafume is mixed in range from 25 to 100% by weight sodium silicate in treatment solution. In the results, slump of concrete is tend to reduce with higher content of recycled coarse aggregate. It can be decreased in 50% in slump and 30% in compressive strength of concrete, respectively, with 100% untreatment recycled coarse aggregate in mix. Recycled coarse aggregate can be improved absortion and reaction of surface by treatment in sodium silicate 5% solution. Hence, concrete can be improve in slump and 20% in strength with treatment aggregate. The suitable time for treatment is 3-4 hours in sodium silicate solution. Moreover, The replacement of silicafume in solution with 1 -1 of ratio can be improved in surface of recycled coarse aggregate during 4 hours. Then, concrete can be incresead in 70% slump and 28% in compressive strength, rspectively, with treatment aggregate in sodium silicate – silicafume solution.