Mechanical properties and frost resistance of self-healing concrete based on expended perlite immobilized bacteria

Abstract

• Self-healing concrete was prepared by pre-wet with SHA. • The compressive strength of self-healing concrete with SHA of 0.6 m 3 was 36.1 MPa. • SHA can improve the frost resistance of concrete. The existing research on self-healing concrete based on Microbial-induced carbonate precipitation (MICP) focuses on the crack-healing effect. However, there are limited studies on the physical and mechanical properties of such concretes. In this paper, the effects of different mixing methods and self-healing agent (SHA) particle size on SHA crushing rate, apparent density, and mixture strength are experimentally investigated. The optimal particle size of the SHA was determined as 1–2.36 mm. Also, it was shown that the SHA should be put in first when mixing. Considering the particle size and mixing method, self-healing concrete specimens with two different sizes and five dosage gradients were prepared. The resulting change in compressive strength and splitting tensile strength of concrete with the SHA amount was determined. Also, the change in frost resistance of specimens after 200 freeze–thaw cycles was evaluated. The results indicate that the compressive strength and splitting tensile strength of concrete gradually decrease with the increasing amount of the SHA. The splitting tensile strength decreases slightly compared with the compressive strength of self-healing concrete. However, the frost resistance of concrete increases firstly and then decreases with the increase of SHA content. Therefore, when the content of the SHA is 0.4 m 3 , the frost resistance of concrete is the best.