Effect of Gap Gradation on Compressive Strength of Recycled Aggregate Concrete

Abstract

Use of well graded aggregates in concrete is one of the key parameters to ensure proper strength of the concrete. Green concrete on other hand is need of the day. Therefore, this research paper presents laboratory investigations of compressive strength due to gap gradation of coarse aggregates in green concrete cubes. Green concrete was developed using demolishing waste as coarse aggregates. Five batches of cubes with 5 cubes in each batch were prepared by omitting 1”, 3/4”, 1/2”, 3/8” and #4 sizes in turn. In these batches conventional and recycled aggregates were used in equal proportions. Two more batches of the cubes; one with well grades conventional aggregates, and other with well graded recycled aggregates were also prepared. For preparation of all cubes, a 1:2:4 mix with 0.5
water/cement ratio was used. Slump value of all batches was determined. All the specimens were cured for 28 days by standard water curing. After curing, weight and compressive strength of the specimens were determined. From the obtained results, it is observed that omission of smaller size aggregates has least effect (3%) on compressive strength. On the other hand, if larger sizes are omitted, then the residual strength of the concrete is about 67%.