Slant shear strength of hybrid concrete made with old and new parts using reactive and inert waste powders

Manufactured reactive powders, as a silica fume, are usually used in production of high strength concrete with for retrofitting purposes of concrete structures. The efficiency of inert waste glass powder in hybrid concrete fabrication has not been widely investigated, thus further studies are essentially considered in this area. In the present study, hybrid concrete prisms with size of 10x10x30 cm have been made with old ordinary concrete (OC) and new high strength concrete (HSC). High strength of new concrete part of these prisms is achieved via using of waste glass powder, silica fume and mixture of them. The roughness of interfacial surface between old and new parts of hybrid concrete is improved in various manners with utilizing sand blast, holes and grooves. Performance of these elements has been measured in terms of slant shear strength and mode of failure. The results have been shown that there is a relatively similar strength with using retrofitted concrete made with the used powder which includes silica fume, glass powders, and their mixture, the mixture of both powders, namely, silica fume and waste glass powders is regarded a best choice in the present stud. It is demonstrated also that the grooved interface between old and new concretes induces proper strength equivalent to 89% of control concrete prisms strength.