Enhanced erosion resistance of cement-treated bricks using multiple biological surface treatments

Water erosion can deteriorate cement-treated bricks. The goal of this study was to investigate the use of multiple biological surface treatments (BSTs) on cement-treated bricks to enhance their resistance to water erosion. Calcite crystals were precipitated on the surface of cement-treated sand bricks by the microbial-induced calcite precipitation (MICP) technique. Multiple BSTs with MICP were used to enhance the properties of the cement-treated bricks further. The experimental results showed that, after a single BST, the flexural strength of the cement-treated bricks increased from 500 kPa to 750 kPa and the compressive strength increased from 3000 kPa to 4000 kPa. Erosion and water absorption were reduced by 71.2% and 16.3%, respectively. Compared with cement-treated bricks without any BST, the cement-treated bricks with triple MICP BSTs showed increases of nearly 140% and 100% in peak flexural and compressive strength, respectively. In addition, the triple BSTs resulted in 32% less water absorption compared with cement-treated samples without any BST. The surface of cement-treated bricks with triple BSTs was found to resist accelerated erosion over a 60 min time period. Overall, the results showed that BST can strengthen the erosion resistance of cement-treated bricks.