Preparation And Structural Characterization Magnesium Oxychloride Cement

Sorrell cement is also called magnesium oxychloride cement,it is composed of MgO,MgCl2 and H2O,because of its main ingredient is magnesium,so-called magnesium cement.Magnesium cement has same advantages,such as early strength,high strength,fast-setting,low alkalinity,strong bond,good decorative effect and anti-corrosive brine,etc.,Currently,there are a large number of domestic and foreign institutions and scholars had in-depth research on it,but some drawbacks of magnesium cement is not resolved,such as back to halogen,easy to deformation,etc.so it has been a certain degree of constraint in practical application process.Active magnesium oxide is part of of the magnesium cement,In this paper,we use two methods prepared active magnesium oxide,one is microwave sintering magnesite,the other is using high temperature to calcine magnesite.Determined its activity by the citric acid,under different calcining temperatures and time of magnesite,we determine the best calcining conditions of magnesia by testing activity of magnesium oxide.Then,we analyse two preparing methods and calcination temperature impacting on activity of magnesia and magnesium cement's microstructure.In order to study the structure of the magnesium cement,by changing chemical proportion of the magnesium oxide,magnesium chloride and water and the magnesium oxide's preparation temperature,explore different stoichiometry and temperature impacting on magnesium cement morphology and microstructure.Finally,we do a doped experiment on magnesia,stoichiometric of magnesia is 5.5:1:12 adding phosphoric acid of 0%,1%,2%,3%,sample conservation 7 days in the air,soaked in water for 3 and 7 days,we analyzed phosphoric acid impact on magnesia.The results showed that:if the type of preparing magnesium oxide is different,its activity is also different.The activity of microwave sintering preparing magnesium oxide is higher than the activity of calcination preparing magnesium oxide,and with the calcination temperature increasing,the activity is decreased;If we use microwave sintering method,when the temperature is 700? that magnesium oxide's activity reachs the highest in this case,if using calcination method,when the calcination temperature is 800? that magnesium oxide's activity reachs the highest.The raw materials' ratio of Magnesium cement is different,the corresponding XRD analysis results are very consistent with the theoretical,magnesium oxide's ratio of raw materials and preparation temperature have a certain impact on microstructure of magnesium cement.With increasing MgO content,Magnesia becomes more dense,and the ratio of raw materials is M5.5/H 12,it have best dense;With increasing water content,Magnesia become loose,when the ratio of raw materials is M4.5/H15 its structure become worst;Ratio of raw materials is M6.5/H12,MgO calcination temperature has little effect on the magnesia,when the ratio of raw materials is M4.5/H12,when MgO calcination temperature is 850 ?,dense of magnesia is best.Phosphoric acid can improve the performance of Magnesia,it has the best effect of improving when content of phosphoric acid was 1%.