Preparation and properties of a low-cost magnesium phosphate cement with the industrial by-products boron muds

Abstract Boron muds are the by-products in the production of borax. As its too small particle size and high alkalinity, the piled boron muds could cause some serious environmental problems. Magnesium phosphate cement (MPC) is usually prepared by calcined magnesia (MgO), phosphates and retarders. Boron muds are mainly composed of magnesite and forsterite. Calcined boron muds containing periclase (MgO) could be used as magnesia raw materials to prepare MPC. The properties of the boron muds before and after calcination were studied. After calcination, the tests on workability, mechanical performances, hydration products and microstructures of the MPC pastes prepared by calcined boron muds instead of dead burned MgO were carried out. Furthermore, the properties of MPC pastes with partial substitution of dead burned MgO by calcined boron muds were also investigated. The results show that the pastes with 40% dead burned MgO replaced by calcined boron muds showed sufficient setting time, good fluidity and high compressive strengths. Therefore, partly substituting dead burned MgO with calcined boron muds in MPC production was recommended to deal with the piled boron muds.