Evaluation of effects of multi-varied atmospheric curing conditions on compressive strength of bacterial (bacillus subtilis) cement mortar. (10th September 2019)

• Record Type: Journal Article
• Authors: Abdulkareem, Muyideen; Ayeronfe, Fadeelat; Majid, Muhd Zaimi Abd; Mohd.Sam, Abdul Rahman; Kim, Jang-Ho Jay
• Is Part Of: Construction & building materials. Volume 218(2019)
• Page Start: 1
• Page End: 7
• Publication Date: 2019-09-10
• Subjects: Bio cement mortar -- Bacteria -- Atmospheric curing conditions -- Compressive strength -- Self-healing; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2019.05.119
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Curing conditions effects on compressive strength of bio cement mortar. Combination of varying temperature and relative humidity on bacteria activities. Combination of varying wind speed and sunlight exposure on bacteria activities. Compressive strength comparison at 7 and 28 days. Abstract: Addition of calcite-producing bacteria is a relatively new technique used globally to produce self-healing concrete/cement mortar as well as to increase compressive strength and durability. Due to different atmospheric conditions around the world, the performance of these bacteria will vary due to different curing conditions. In this study, the effects of different atmospheric curing conditions on the compressive strength of bio cement mortar (BCM) are examined. The atmospheric conditions (curing) are varied by combining different temperature and relative humidity, and wind speed and sunlight exposure time. The microorganism used is Bacillus subtilis, and it is added to concrete mortar through direct mixing. The concentration of the bacteria solution is 10 9 cells/ml and two volumes of 30 ml and 50 ml are applied. Two control specimens - water-cured bio cement mortar (BC) and water-cured cement mortar (NC), are made to serve as baselines for comparison and evaluation of the effects of the curing conditions. The results showed that increased temperature, relative humidity and wind speed increased the compressive strength of BCM. However, increased sunlight exposure time decreased the compressive strength. The results indicated that atmospheric conditions influence the performance of bacteria in BCM. The BCMs had higher 7 and 28 days compressive strength than the control sample (water-cured cement mortar). The minimum and maximum 7 day increments were 53.7% and 120.6% respectively, while the 44.9% and 130.6% respectively were the 28 day. The results show that calcite-producing bacteria improves the compressive strength of cement mortar, however, the environmental curing conditions of the produced BCM will influence the calcite-producing ability of the bacteria.