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 artificial aggregates by cold-bonding disk granulation. And a novel approach for strengthening mechanical properties and improving CO2 sequestration of artificial aggregates was proposed based on using microorganisms. The microorganism enhanced the mechanical properties, porosity and microstructure of artificial aggregates. The apparent density, crushing strength and water absorption of artificial aggregates were increased to 2620 kg/m3, 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 CO2 fixation of artificial aggregates increased from 7.39 wt. % to 16.00 wt. % due to the existence of microorganism. The compressive strength of concrete indicated that artificial 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 CO2 emission reduction, displayed good potential for future applications.

Effect of waste concrete powder on concrete properties and microscopic mechanism analysis

“…[18,19] Remade concrete materials, due to the powder surface roughness, contains a lot of uneven parts, the surface of the powder wrapped with cement and other impurities, may lead to recycling of concrete materials absorb water quickly. [20][21][22][23] Through life cycle assessment, Zhang [24] and Senthil [25] found that the use of concrete powder is bene cial to environmental protection and resource conservation.…”