Microbial damage mitigation strategy in cementitious materials exposed to calcium chloride

Deterioration of concrete pavements in the United States has increased over the past decade. This damage is triggered by two possibilities: classic freeze-thaw behavior, as well as the formation of calcium oxychloride (CAOXY) that originates from calcium chloride (CaCl2) in deicing salt. CAOXY is an expansive phase leading to damage and cracking in the cementitious matrix. This study investigates use of alkaliphilic, spore-forming bacteria to mitigate formation of CAOXY. Cementitious samples were made with ordinary portland cement (OPC); OPC combined with nutrients; and OPC combined with bacteria and nutrients. Low-temperature differential scanning calorimetry, thermogravimetric analysis, sorption analyzer, and acoustic emissions were used to quantify the amount of CAOXY, calcium hydroxide, microstructural change, and damage caused by CaCl2 salt in the cementitious samples, respectively. It was observed that the addition of bacteria changes in the micropore structure of cement pastes and significantly reduces the formation of CAOXY. (C) 2018 Elsevier Ltd. All rights reserved.