Abstract

Effect of recycled aggregate in concrete can be useful for environmental protection. Recycled aggregates are the materials for the future. The environmental impact of concrete constructions and improves natural resource conservation. The results of a test programmer to study the use of recycled concrete aggregate (RCA) into highstrength 50 N/mm 2 or greater. The effects of coarse RCA content on the compression strength, bulk density and durability properties of such concretes have been established. The results showed that up to 30% coarse RCA had no effect on concrete strength but there after there was a gradual reduction as the RCA content increased. Concrete mixes with partial replacement of natural aggregate with (0,50,100) recycled aggregate. the effects of silica fume (SF) in the concrete mix design to improve the quality of recycled aggregates in concrete are presented. Cement was replaced with SF at 0%, 5% and 10%.

At all the test age the tensile split strength gain of the natural aggregate concrete mixture (NA) with and without SF was higher than that of the recycled concrete mixtures. Continuous and significant improvement in the tensile splitting strength of recycled aggregate concretes SF was observed. Similar to compressive strength test results, concrete incorporating 10% SF and containing 4/12 mm fraction recycled aggregates showed better performance among recycled aggregate concretes.