Research On Effect Of Composition On Properties Of Magnesia Cement

Magnesium oxychloride cement is made by Magnesium Oxide and Magnesium Sulfate active solution to form the gas hard magnesia cementitious material,because of its light weight,excellent fire resistance performance,low thermal conductivity,is widely used in the production of lightweight thermal insulation board,insulation materials,refractory material etc..Relative to magnesium chloride cement,the report of magnesium oxide cement is less,because of the low mechanical strength of magnesium oxide cement compared with magnesium chloride cement.However,it is obvious that magnesium oxide cement has the advantages of high temperature resistance,high temperature resistance and low corrosion resistance.In this paper,the basic properties of sulfur oxygen magnesium cement are studied in the paper.This paper first in the magnesium oxychloride cement composition of water control sulfur ratio,oxygen sulfur ratio,citric acid three basic variables,experimental study on the single factor,determine the optimal values of three variables and the optimal range of variables,and then expand the orthogonal experiment,and analyzed the compressive strength reached the highest value,the the optimum mixture ratio for water sulfur ratio:oxygen sulfur ratio:citric acid=1.8:0.9:1.2.Respectively adding three kinds of mineral admixture of fly ash,slag,silica fume was doped test of magnesium oxychloride cement based on the ratio of the.In order to meet the requirements of strength,to test its water resistance,determine the amount of three kinds of mineral admixtures range.On the basis of orthogonal test,the optimum experimental results showed that the three kinds of admixtures have the effects on improving the performance of magnesium oxychloride cement,the orthogonal experiment that admixture was better than single mixing effect,the best proportion for fly ash:Powder:silica fume =15%:10%:10%.At this point,the compressive strength of the 28d is the best,which can reach 65.7MPa,and the water resistance softening coefficient can reach 0.94.On the basis of the basic composition determination of the basic ratio,adding three kinds of additive citric acid three sodium,sucrose,water glass to the sulfur oxygen magnesium cement single mixed test.In order to meet the requirements of strength,to test its water resistance,determine the amount of each of the three types of additives.On the basis of orthogonal test,the optimum experimental results showed that the three kinds of additives have the effects on improving the performance of magnesium oxychloride cement,the orthogonal experiment that admixture was better than single mixing effect,the best proportion was three citric acid sodium:sucrose:water glass ＝1%:1.5%:1%.At this point,the compressive strength of the 28d is the best,which can reach 63.5MPa,and the water resistance softening coefficient is 0.95.Finally,on the basis of macro research on magnesium oxychloride cement,the microstructure morphology and phase composition analysis by scanning electron microscope and XRD diffraction analysis of magnesium oxychloride cement in the age of 3D were analyzed,it was found that the adding of citric acid can promote the formation of magnesium oxychloride gel phase.Mineral admixture can be observed in the presence of the 5 · 1 ·7 phase,and the presence of the 3 · 1 ·8 phase can be observed.These are the main support for the formation of high strength in the early hydration process of magnesium oxide cement.There are detailed discussions in this article.