Preparation of artificial aggregate using waste concrete powder and CO2 fixed by microorganisms

Abstract

High carbon emissions, shortage of natural aggregates and environmental pollution of waste concrete powder (WCP) have become three imperative crises faced by the traditional concrete industry. The waste concrete crushed to prepare aggregates always has poor mechanical properties and low utilization of waste powder. In this paper, WCP was used to prepare arti cial aggregates by cold-bonding disk granulation. And a novel approach for strengthening mechanical properties and improving CO 2 sequestration of arti cial aggregates was proposed based on using microorganisms. The microorganism enhanced the mechanical properties, porosity and microstructure of arti cial aggregates. The apparent density, crushing strength and water absorption of arti cial aggregates were increased to 2620 kg/m 3 , 9.1 MPa and 4.8 %, respectively. It showed a denser microstructure because more mineralization products with well crystallization reduced the porosity from 20.98 % to 13.88 %. The CO 2 xation of arti cial aggregates increased from 7.39 wt. % to 16.00 wt. % due to the existence of microorganism. The compressive strength of concrete indicated that arti cial aggregate could substitute the nature aggregates partially without affecting its strength, and the better rate should be controlled within 50 wt. %. This method has obvious effect on waste resource utilization and CO 2 emission reduction, displayed good potential for future applications.