Influence of direct urease source incorporation on mechanical properties of concrete

Strength augmentation of cementitious materials is a highly studied research area and incorporation of microbes in cementitious materials has drawn attention of many researchers worldwide recently. While most of the research work has been performed by using microbes, the cost and maintenance of involved microbes causes significant increase in overall cost. Moreover, involvement of microbes makes it difficult to implement the technique as it requires expert supervision. Many researchers have tried to minimize the cost by using various innovative ways to grow and maintain microbes. However, no study has been performed to completely replace the microbes to achieve comparable enhancement in the properties of the cementitious materials. Generally, ureolytic bacteria are used as a source of urease enzyme (EC 3.5.1.5) to perform the biocementation process. However, the involvement of bacteria makes the on field application of the process difficult. The present study, for the very first time demonstrates the direct utilization of plant-based urease for the process of calcium carbonate precipitation. Various urease rich seeds of plants such as watermelon seeds, soya beans and pumpkin seeds were directly added to the concrete mix in powdered form along with urea and calcium hydroxide in measured quantities. Results showed a noteworthy improvement in the properties of treated concrete specimens as compared to control specimens.