Utilization of Eco-Friendly Construction and Demolition Waste Materials in Soil Improvement

Abstract

This study comprehensively assesses using Concrete Waste (CW) and Rubber tire Fly Ash (RFA) eco-recycled materials to enhance the mechanical characteristics of cohesive soil obtained from Al-Araby district in Mosul city/Iraq. These materials are added by 3, 6, 9% CW and 6, 12, 18, and 24% of RFA of soil dry weight and passed sieve (No.40), in addition to adding 3, 6, and 9% cement as an activator to soil-RFA mixture. Several techniques have been used, such as mercury intrusion porosimeter, X-ray diffraction, unconfined compressive strength, water retention ability, and axial sample compressibility. In addition, curing period effects on soil-soil-eco-recycled mixtures have been evaluated. Results showed that 18% RFA had been concluded to be the optimal percentage. Also, adding eco-recycled materials exhibited an alteration in soil pore structure distribution from meso to micro-meso pore size for CW and to predominantly micropore size for RFA, and modifying the treated soil compressive strength properties. At the same time, varied effect on maximum dry density has been observed between the development in CW addition and decrement in RFA, accompanied by decrement in soil compressibility and water retained ability for both eco-recycled materials. Also, a 5.5% cement activator addition to the soil-RFA mixture was the optimum cement activator percentage. The curing period tests of soil treated with (CW) and soil-18%RFA-5.5% cement activator reflected cement’s continuous pozzolanic reaction ability in concrete waste additive and cement activator, respectively.