Mechanical properties and durability of bio-blocks with recycled concrete aggregates

Harnessing bio-processes to improve the mechanical properties of building materials have gained interest in developing green construction. One of the bio-processes utilized to improve the mechanical properties of building materials is the bio-mineralization of calcium carbonate by the activity of the urease-positive bacterium. In this research, the recycled concrete aggregates, as one of the main constituents of construction and demolition wastes, were used to produce bio-blocks by the bio-mineralization of CaCO3 and the results were compared to bio-blocks produced with natural aggregates. Furthermore, the durability and mechanical properties of both types of bio-blocks were investigated. The difference in compressive strengths of bio-blocks made with both aggregates was less than 10%. The results showed that bio-mineralization reduced the water absorption of the RCA bio-blocks, which is one of the drawbacks of recycled concrete aggregates. In addition, durability tests revealed that the bio-blocks maintained their strength under freeze thaw cycles and high temperatures.