Improvement of the Mechanical Properties of P300 Kaolinite Using MICP in the Low Water Content Range

Reducing greenhouse gas emissions is one of the major concerns of our time. That is why eco-building materials such as raw earth are gaining interest. It requires low grey energy due to its manufacture and presence on site. The problem is that the dehydration of its clay fraction causes its shrinkage, generating cracks. Many researchers have tried to solve this problem. Microbially induced calcite precipitation (MICP) appears as a potential solution. Its use has been extensively studied to improve inert soils such as sands, but only some studies have focused on its use in loaded and low-permeability clays. In this study, we aim to demonstrate the proper functioning of MICP and its positive impact on clays. To do so, we prepare low water content clay samples with the “Soil-Mixing” technique, mixing our dry powder of yellow kaolinite P300 with a bacterial and calcifying solution to form a paste that will be compacted to a fixed dry density. These cylindrical samples are kept at a fixed water content for 3 days and are then subjected to a simple compression test. The comparison of the significant stresses obtained attests to the increase in strength of the material treated by MICP, and the use of the Dietrich Frühling calcimeter confirms the presence of calcite in the MICP treated kaolinite. The use of the MICP process in clays is very promising. This study has highlighted the improvement of mechanical strength through MICP treatment by “Soil-Mixing” method in clay materials with low water content. We intend to apply this treatment in raw earth construction materials such as compressed earth blocks.