The influence of standing time and content of the slurry on bio-sandstone cemented by biological phosphates

• A new method was found to bind loose sand particles into bio-sandstone.
• Loose sand particles can be cemented by biological barium hydrogen phosphate.
• Bio-sandstones cemented by biological phosphates have good mechanical properties.

Loose sand particles can be cemented by the microbial inducing the slurry of barium hydrogen phosphate precipitation into a bio-sandstone with certain mechanical strength, which is a new technique to bound loose sand particles with biological phosphates. This paper confirms the feasibility of biological phosphates binding loose sand particles and presents results from laboratory researches on the influence of standing time and content of the slurry on the mechanical properties of sandstone biological phosphates bound. The results show that standing time and content of the slurry have a strong influence on the mechanical properties of bio-sandstone. The best standing time, which is 24 h, of the slurry mixing with quartz sand and obtained higher compressive strength of sand column (bio-sandstone) than three other standing times. The maximum compressive strength of bio-sandstone is 2.1 MPa when the content of the slurry reaches 50% with 24 h standing time. In addition, the ingredients of the slurry and bio-sandstone are mainly hydrogen phosphate barium through XRD analysis. The corresponding variation of porous characteristics of sand column is observed by scanning electron microscope (SEM) and indicated that the cementitious materials between quartz sand are mainly irregular sphere clusters in shape. The technique can be used in other fields: including dust-fixing, foundation reinforcement, slope and so on.

Bio-calcite cement and portland cement can release ammonia and carbon dioxide respectively, and these gases have a negative impact on the environment. In response to these aspects, a new binder should be selected to cement loose particles, and bio-phosphate cement (microbial induced deposition phosphate) was taken into our consideration due to the presence of phosphate minerals in the nature. In this research, barium hydrogen phosphate by microbial deposition can well bind loose sand particles into sandstones.Figure optionsDownload as PowerPoint slide