تحضير ودراسة اسمنت فوسفومغنيزي على أساس الدولوميت والفوسفـات.

Abstract

In this work, it is the possibility of the preparation of cement phosphomagnisium, which quickly hardened at room temperature, starting from a local raw material available and no expensive which is dolomite. Dolomite was calcined partially, to obtain a mixture of magnesium oxide and calcium carbonates (MgO, CaCO3).This mixture was then used to form a phosphomagnesity bond after addition of different compounds such as: MgCl2, MgSO4, NH6PO4, H3PO4, Na2B4O7.10H2O and H2O with different percentage (preparation of three solutions). The first stage percentages are processed during preparation of the two solutions. When we studied the third solution we added cement kiln dust to improve the properties of the phosphomagnesium cement samples. Different techniques were used to investigate the physical properties of this cement are: DRX, FTIR, RAMMAN, MEB, DSC, tensile strength and bond strength. The results obtained show that this cement hardened in 15 to 20 min, the value of tensile strength and bond strength is at 2.95 MPa and 3.4 MPa respectively, comparable or even better than that found in the literature. The addition of 20 % weight of cement kiln dust improved the mechanical properties of this cement. The study of the structure of this cement shows the formation of a phase called Struvite in the case of cement prepared from the first and third solution, and the phase struvite with Mg(PO2)4S410H2O for cement prepared with the method using the second solution. The decomposition of this cement starts at 70 °C. The results of this work can show that it can be used well as cement phosphomagnisium at lower cost in the place of existing cement on the market.