Effect of ion concentration in crack zone on healing degree of microbial self-healing concrete

In this paper, the changes of Ca2+ and CO32- in the crack zone with the concentration and the cumulative molar amount over time were measured, and then the crack healing depth was calculated theoretically. The cumulative molar amount of Ca2+ in the original crack area is 50.4 mmol, and the cumulative molar amount of CO32- is 3.17 mmol; if the dissolved Ca2+ is completely converted into calcium carbonate, the theoretical calculation of crack filling volume ratio is 24.87%, and if the dissolved CO32- is completely con-verted into calcium carbonate, the theoretical calculation of crack filling volume ratio is 1.57%. In addi-tion, after the addition of microbial self-healing agent 1 and 2, the crack area healing rate was increased to 98.5% and 98%, respectively; the water resistance penetration repair rate was increased to 100% and 98.5%, respectively; and the crack filling volume ratio was 32.45% and 30.05%, respectively. The accumulative mole amount of Ca2+ in the crack zone reached 73.85 mmol on 36 days after the addi-tion of microbial self-healing agent 1; and the accumulative mole amount of CO32- in the crack zone reached 36.84 mmol on 36 days after the addition of microbial self-healing agent 2. According to the the-oretical calculation, the filling volume ratio of microbial self-healing agent 1 and 2 are 36.84% and 39.58%, respectively, and the deviation from the test value is 13.5% and 31.7%, respectively. (C) 2021 Elsevier Ltd. All rights reserved.