An investigation of the compatibility of different approaches to self-healing concrete: The superabsorbent polymers and microbially induced calcite precipitation

Abstract

The concept of the self-healing concrete, thus an improvement of the durability of concrete structures, has become a widely investigated topic in recent decades. The aim of this study is to examine a possible combination of two existing approaches to the spontaneous crack-sealing – the biologically driven calcite precipitation and the addition of superabsorbent polymers (SAP) into the concrete matrix. Firstly, the paper compares the absorption rate of SAP in various solutions, including a nutrient-based solution which is used in the bio-concrete. The results show that the ionic composition of the liquid influence the swelling capacity greatly. In this study, the absorption rate of SAP in the nutrient-based solution is as low as 6% of the rate in distilled water. Thus, this finding could indicate a possible drawback of the combination of the proposed self-healing approaches. Further, this paper determines the impact of the SAP addition to cement paste with different water/cement ratios. In this experiment, the SAP is applied in various dosages (1% and 0.5% by c. w.) and states (a dry state or a fully swollen state). The conducted flowability and mechanical properties tests indicate a profound, generally negative, impact of the SAP addition on the cement paste characteristics. The paper then discusses possible adjustments of the SAP-cement paste composition and compares the present results with previous studies.