Loose sand particles cemented by different bio-phosphate and carbonate composite cement

• A new bio-cement was applied to bind loose particles into bio-sandstone.
• Loose particles can be cemented by different bio-phosphate and carbonate composite cement.
• Ammonia/ammonium can be effectively become into struvite in injection process.
• Permeability, porosity, strength and microstructure of the bio-sandstones were investigated.

Loose sand particles could be cemented by the microbial induced phosphate and carbonate precipitation into a bio-sandstone with a certain mechanical strength when the Sporosarcina pasteurii contained K2HPO4·3H2O and the mixture solution of urea and MgCl2 in the 1:1 of volume ratio were injected by a peristaltic pump into quartz sand mold. The result shows that loose quartz sand particles are well cemented into a bio-sandstone, and the compressive strength of bio-sandstones is greater than 1.0 MPa. Ammonia/ammonium was produced during the hydrolysis of the urea and could be effectively become into environment-friendly struvite in the cementation process. In addition, the ingredients of the bio-sandstones were mainly quartz sand, struvite and hydromagnesite through XRD analysis. The internal microstructure of bio-sandstone was observed by SEM and the bio-phosphate and carbonate composite cement between sand particles indicated the shape was mainly irregular particles. The solidified layer of the surface of dust and sand particles was formed after spray bio-phosphate and carbonate composite cement, and wind erosion rate of dust and sand is 0 g/m2/h and 0 g/m2/h, respectively.