Manufacture of Lightweight Thermal Insulation Concrete Using Recycled Aggregates and Syrian Pozzolan

Abstract

This research is part of the national project for the recycling and reuse of demolished building and infrastructure in Syria. It is an attempt to find a lightweight concrete mix with local components suitable for use in the concrete mixes with acceptable resistance to pressure and low thermal conductivity and good workability. Syrian Pozzolan aggregate (PA) was used with recycled concrete (RCA) aggregates to manufacture concrete mixtures for use in a concrete mixes or in the outer cover of the buildings, as slabs of inclination on the last roofs, and in the non-load-bearing exterior walls to benefit from it as a thermal insulator and get rid of important quantities of rubble that constitute an environmental and economic damage on the government in the reconstruction phase. A practical program was designed to include 12 groups for mixing concrete samples, where groups were distributed as follows: 6 groups, natural aggregate (NA) were mixed with PA, and also 6 groups, PA were mixed with RCA. The replacement percentage of PA was 90%, 85%, 80%, 75%, 70%, and 65% of NA and RCA. Replaced PA was from the total volume of NA due to the different densities. The results showed that the compressive concrete have good values related to the Syrian standard, and the thermal conductivity decreased very significantly. The use of 90 %PA with 10% RCA is an optimum ratio, as CSC value was 58 MPa, considered relatively high, density was 1529 Kg/cm3 and it is light compared to ordinary mixtures of more than 1800 Kg/cm3, for thermal conductivity it is also low. The use of PA and RCA improved the thermal performance of concrete mixtures with a relatively lightweight.