Studies on Cent Percent Utilization of Recycled Coarse and Fine Aggregates in the Construction Industry

Abstract

As a measure of conserving the resources and for creating eco-friendly environment, studies have been conducted on recycled demolished concrete aggregates (RCA) for their complete usage in the construction industry. The method adopted comprises improving the structure, physical and mechanical properties of RCA. The RCA that are obtained from impact jaw crusher, the surface of these aggregates is improved by processing it through miller machine by way of ball rotation action, where the surface defects and brittle fracture are removed without affecting the permanent mortar adhered on the aggregate, to these modified aggregates which are porous and weak in structure, the surface of the aggregates is subjected to various treatments to improve its structure. The techniques used are densification, hydrophobization, polymerization, and a combination of polymerization & densification. On these combinations, the various dosages of chemical treatments were applied and tested for their properties on coarse and fine aggregates. Finally, a combination of 2.5% of Lithium silicate treatment on coarse aggregates and 1 % colloidal silica treatment on fine aggregates has given satisfactory results in usage in concrete/cement mortar mass. On these combinations, the durability and microscopic studies (SEM, EDS, XRD) were done and it was observed that the combination has more association of silica with calcium and these resulted in more formation of C-S-H, and a dense interfacial transition zone. The aggregates applicability was tested in the field by using it for various civil works. All the tests and analyzed parameters indicate that the treated aggregates are future materials and act as a complete replacement for natural aggregates.