Crack healing in cement mortar using enzyme induced calcium carbonate precipitation

• Published in: Construction & building materials 2023-08, Vol.394, p.132223, Article 132223
• Main Authors: Junwale, Rishabh, Nikode, Aishwarya, Bhutange, Snigdha, Latkar, M.V.
• Format: Article
• Language: English
• Subjects: Biocementation; Cement mortar; Crack healing; EICCP; Urease; Watermelon seeds
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.132223

•Plant-based urease enzymes derived from urease-rich seeds offer a breakthrough approach to crack healing.•Pulverized watermelon seeds serve as a valuable source of urease to produce calcium carbonate in crack repair.•The specialized suspension, containing urea, watermelon seeds’ urease, and calcium hydroxide, effectively repairs cracks in cement mortar.•The biocementing suspension achieves 90% compressive strength recovery on day 7, indicating complete crack repair and enhanced water tightness. The current study highlights a breakthrough approach to crack healing by harnessing the potential of plant-based urease enzymes derived from urease-rich seeds. In this investigation, pulverized watermelon seeds (Citrullus lanatus) served as a valuable source of urease, which facilitated the production of calcium carbonate for crack repair in cement mortar. The healing process involved introducing a specialized suspension, consisting of urea, watermelon seeds’ urease, and calcium hydroxide, into the existing cracks of the specimens. Prior to treatment, the cracked mortar specimens exhibited a substantial 35% reduction in compressive strength as compared to the control specimens. The application of the biocementing suspension led to complete repair of the cracks, resulting in an impressive recovery of approximately 90% of the compressive strength on 7th day, comparable to the control specimens. The UPV results clearly indicated that the crack was healed on the 7th day thus confirming that the proposed biocementing suspension was able to repair the crack completely within 7 days of application. Moreover, the treated i.e experimental specimens demonstrated significant improvements in water tightness, indicating remarkable effectiveness of this crack healing methodology.