Optimization of the recycled aggregate processing using the full factorial design approach, chemical, physical and microstructural characterization of treated aggregates by pre-coated with cementitious paste

Abstract

The present study aims to study the treatment of (RCA) faction (16/25) by their encapsulation into cement slurry with a (W/C) ratio of (0.5). A complete factorial plan 23was applied by considering three independent factors, namely the state of RCA (GR), the soaking time into slurry (DT) and the hardening time (RCA) (A). The selected responses are the compressive strength and the water accessible porosity (voids) of concrete incorporate treated (RCA), after 28 days of curing. The results were analyzed using the statistical software JMP Trial 16.The compressive strength of concretes showed an increase between 20.5 % and 21.04 % with respect to (NCA).However, the porosity of concretes showed a decline with respect to RCA. The main factor that conditions the two responses is the cure time (A), followed by the RCA state. According to the physical characteristics of RCATi, the encapsulation leads to increased water absorption, bulk, and absolute density. The XRD and TGA techniques confirmed the presence of hydrates and quartz in RCA and RCAT. The microstructural analysis of RCAT seems to be in favor of (dry RCAT) soaked in the cement slurry for 10 min where the adhesion is stronger and the (ITZ) is denser.