Healing of Generated Cracks in Cement Mortar Using MICP

Abstract

This research is carried out to investigate pre-existing repair cracks in cement mortar using the microbiologically induced calcium carbonate precipitation (MICP) technology. In the study, 20-cylinder mortar samples (45 mm in diameter and 40 mm in length) were split to have cracked width of various sizes. Out of twenty cracked samples, sixteen samples of average crack width ranging from 0.12 to 1.3 mm were repaired using the MICP method, while four cracked samples, with an average crack width ranging from 0.16 to 1.55 mm were soaked under distilled water. The water permeability and split tensile strength (STS) of these repaired mortars were tested. The amount of CaCO3 precipitated on the cracked mortar surfaces was evaluated. The results indicated that the MICP repair technique clearly reduced the water permeability of the cracked samples within the range of 73 to 84 %; while water-treated samples were too weak to undergo test. MICP-repaired samples had STS ranging from 29 to 380 kPa after 24 rounds of treatment. A relationship between the STS and percentage amount of CaCO3 precipitated was observed for samples with an average crack width between 0.29 and 1.1 mm, which indicated that STS increased with percentage increase in CaCO3 precipitated on the crack surfaces.

Microbial-Induced Carbonate Precipitation Improves Physical and Structural Properties of Nanjing Ancient City Walls

“…XRD analysis showed that CaCO 3 in calcite form was present in both ancient bricks and MICP filler. On one hand, this result validated that S. pasteurii can successfully utilize chemical components to produce CaCO 3 in the brick cracks; this suggests that S. pasteurii has a similar function to that of Bacillus subtilis species as presented in former MICP-related studies [19,30]. On the other hand, the generated CaCO 3 by MICP appears in calcite form, which is the same form as that of the ancient bricks in this study.…”

“…The remediation of the surface cracks of the ancient bricks involved the configuration and curing of certain sodic particles; the process of bio-calcification during MICP could form CaCO 3 crystals, which could, in turn, be used to fill and bind the generated gaps of the deteriorated masonry [ 18 , 19 ]. In our study, we show that MICP can efficiently remediate both the natural and simulated cracks in the ancient bricks.…”

Coal ash Portland Cement Mortars Sulphate Resistance

“…Portland cement is the material most widely used in the construction industry worldwide and it is estimated that its production releases approximately 7.4% of global anthropogenic emissions of carbon dioxide [1]. The cement industry follows several levers to reduce the unavoidable environmental effects of producing Portland cement, but probably, among all of them, the increase of the period of service-life of the cement-based materials is most important, for instance, by crack reduction [2]. Kulkarni et al (2020) used the technology named "microbiologically induced calcium carbonate precipitation (MICP)" to repair cracks and they found a reduction in permeability in the range from 65 to 85% for cracks ranging from 0.12 to 1.3 mm [2].…”

“…The cement industry follows several levers to reduce the unavoidable environmental effects of producing Portland cement, but probably, among all of them, the increase of the period of service-life of the cement-based materials is most important, for instance, by crack reduction [2]. Kulkarni et al (2020) used the technology named "microbiologically induced calcium carbonate precipitation (MICP)" to repair cracks and they found a reduction in permeability in the range from 65 to 85% for cracks ranging from 0.12 to 1.3 mm [2]. The second one could be the production of blended cements.…”

Mechanical and Thermal Performance of Cement Mortar Incorporating Super Absorbent Polymer (SAP)

“…The desorption of absorbed water from SAP also conserves high internal relative humidity of mortar and thereby mitigate shrinkage of mortar [11,21,22]. Various methods have been investigated to produce self-healing concrete incorporating mineral admixtures as well as bacteria [23,24]. SAP also can be applied to reduce the potential cracking [25,26] as well as to induce self-sealing [27][28][29] of cementitious materials due to the characteristics of SAP, i.e.…”