Bio-cementation of sand, also known as MICP (Microbially Induced Calcite Precipitation), is a rather novel soil-reinforcement process that uses bacterial activity to cement loose cohesionless sand. It leads to the precipitation of calcium carbonate (CaCO3) as calcite crystals on the surface of the particles, that act as ‘bridges’ between them. This process has been industrialised and is now being used for engineering purposes. The aim of this work is to study the growth of these bio-minerals in the medium using scanning 3D X-ray diffraction with time, by also varying different parameters that are known to affect the cementation process.