Study On Acceleration And Aging Performances Of Magnesium Oxychloride Cement

The inorganic adhesives have significant research value,which can solve the problems of formaldehyde emission and flame retardancy of wood-based panels.To study the acceleration and aging performances of magnesium oxychloride cement(MOC),four accelerators were selected in this paper:sodium silicate,sodium aluminate,sodium hydroxide and barium oxide.Through macro-performances(setting time and compressi've strength)and the SIC(stand in cement)rapid aging testing,the changes of hydration productions and the aging performance were investigated systematically.In addition,regulative mechanisms were discussed by some microstructure analysis techniques.The main conclusions were summarized as follows:1.The four accelerators(sodium silicate,sodium aluminate,sodium hydroxide and barium oxide)all can significantly shorten the setting time and promote the hydration reaction of MOC.The main mechanisms were as follows:firstly,amount of heat can be released when the accelerators participate in the hydration reaction;secondly,the introduction of OH-ions can increase the pH of the cement system.Therefore,the progress of hydration reaction was promoted.2.The four accelerators(sodium silicate,sodium aluminate,sodium hydroxide and barium oxide)had no obvious adverse effects on the mechanical properties and had certain feasibility in the field of wood composites.Among them,after adding sodium aluminate and barium oxide,the compressive strength of MOC for 28 days increased by 10.62%and 25.09%respectively.3.The accelerator of sodium aluminate can not only improve the early strength of MOC,and did not affect the development of late strength,even slightly higher.The main results were that the Al(OH)3 colloid generated during the hydration reaction after the introduction of sodium aluminate,which had a certain protective effect on the 5·1·8 crystal and can be filled in the gaps of the cement itself.The increased dense structure eventually leaded to less obvious influence on the later strength of MOC.