Development of new calcium source using limestone and acetic acid solution in MICP

Abstract

Biocement Biocement production from microbially-induced calcium carbonate precipitation (MICP) is an environmental friendly approach for construction works, but the use of calcium chloride (CaCl2) in the conventional MICP process is a cost-limiting factor. The aim of this work is to develop a method for producing soluble calcium ions through two waste sources, limestone powder derived from aggregate quarries and acetic acid derived from fast pyrolysis of lignocellulosic biomass, as a replacement of the reagent grade CaCl2 in the MICP process. The ratio of limestone powder to acetic acid solution was optimized for a desirable calcium concentration with an appropriate pH. Procedures for applying the urease-producing bacteria, urea and calcium solutions were developed for a successful MICP process, and were treated for sand column test. Engineering properties of the biocemented sand, including unconfined compressive strength, and tensile strength, were evaluated as a function of the calcium carbonate content of the product. It was found that the properties of the sand treated using the limestone/acetic acid derived calcium solution were comparable to those treated using reagent grade CaCl2. Collectively, the results indicate that the new MICP process is effective, more sustainable and cheaper compared with the conventional MICP method.