Influence of Curing Media and Mixing Solution on the Compressive Strength of Laterized Concrete

Abstract

Concrete has been a major building material over the centuries due to its strength, durability and versatility. However, despite the numerous advantages of concrete, it is still plagued with several limitations in addition to its high use of raw materials. In order to improve the resilience of concrete mixtures, this study was carried out to investigate the effect of curing media and mixing solution on the compressive strength of concrete mixtures incorporating different proportions of laterite as partial replacement of the conventional fine aggregate. The laterite content in the concrete was varied at 0%, 15% and 30% of fine aggregate, and mixed with bacteria solution or water. The compressive strength of the mixtures was evaluated at 7, 14 and 28 days for concrete mixtures cured in water, bacteria solution, nutrient broth and combined bacteria and nutrient broth. Results from this study indicate concrete mixtures cured in nutrient broth plus bacteria solution have the highest compressive strength followed by bacteria, nutrient broth and water. The improvement in compressive strength due to Bacillus sp. CT-5 (i.e. bacteria used in this study) can be attributed to the precipitation of CaCO₃ at the cell surface as well as within the concrete matrix. This provided a nucleation site which made it to become less porous and permeable and thereby increasing the compressive strength of the concrete cubes. The results of this study can be used to understand how various solutions incorporating bacteria can be used to enhance the performance of concrete. In addition, this study exhibits the viability of using locally available materials such as laterite in concrete mixtures.