Preparation And Properties Of Magnesium Oxysulfate Cement-based Straw Lightweight Composite Materials

The sulphur-oxygen magnesium cement and its products have the advantages of light weight,low density,good volume stability,good fire resistance,good decorative effect,no moisture absorption and return to halogen,mild and non-corrosive to steel bars,and corn stalks are also used in China.Lower rates of renewable resources,while incinerating corn stalks can seriously pollute the air.In order to make full use of the advantages of sulphur magnesia cement and a large amount of corn stalk resources,the composite materials prepared by using sulphur magnesia cement and corn stalk can not only combine the excellent performance of the two,but also complement each other and obtain better performance.The materials can also protect the environment and have an important contribution to the construction of a resource-saving society,with good social and economic benefits.In this paper,the effects of magnesium oxide and magnesium sulfate molar ratio(MgO/MgSO4)and water consumption(H2O/MgSO4)on the mechanical properties and water resistance of sulphur-oxygen magnesium cement were studied,and an optimal mixture ratio was obtained.On the basis of the mixture ratio,the sulphur magnesia cement was modified by using different amounts of citric acid,water glass and polyethylene glycol,respectively,and the test results of mechanical properties and water resistance of the test block were compared.The optimum amount of the best modifier and modifier is selected;the modified sulphur magnesia cement is blended with three different forms and different amounts of corn stover,according to apparent density,mechanical properties and The analysis of the water resistance test results shows that the optimal blending morphology and optimum dosage of corn stalks are obtained.Finally,based on the previous test results,the sulphur magnesia cement-based straw composites are foamed by physical foaming.The sulphur magnesia cement-based straw lightweight composite material with lighter quality and strength meets the requirements.The results show that the molar ratio of magnesium oxide to magnesium sulfate(MgO/MgSO4)and water consumption(H2O/MgSO4)have an effect on the mechanical strength and water resistance of magnesium sulphate cement,when the molar ratio of magnesium oxide to magnesium sulfate When(MgO/MgSO4)is increased,the flexural strength and compressive strength of the magnesium humoxide cement paste are also increasing.When the water consumption(H2O/MgSO4)is increased,the flexural strength and compressive strength are gradually increased.Increase.The flexural strength,compressive strength and softening coefficient of sulphur-oxygen magnesium cement are the best when MgO:MgSO4:H2O=8:1:20,and the 28d flexural strength is 5.6MPa,28d.The compressive strength is 32.5MPa and the softening coefficient is 0.52.Among all kinds of modifiers,the modification effect of citric acid is the best.The compressive strength and flexural strength of sulphur-oxygen cement show with the increase of citric acid content.Firstly,the trend of increasing and decreasing is the best.When the dosage is 0.7%,the modification effect is the best.At this time,the 28d flexural strength is 8.7 MPa,which is 55.4%higher than the benchmark group(5.6MPa);the compressive strength of 28d It is 58.1 MPa,which is 78.8%higher than the baseline group(32.5 MPa);the softening coefficient is 0.88,which is 91.3%higher than the reference group(0.46);when the 6%is incorporated into the 6%segment When the corn stover is used,the composite material has the best performance.At this time,the apparent density of the test block is 1574.2kg/m3,the 28d flexural strength is 13.3MPa,the 28d compressive strength is 33.7MPa,and the water softening coefficient is 0.84.The method of foaming,when the foam content is 3000 ml/kg3 the apparent density is 390.1 kg/m3,the 28d flexural strength is 0*5 MPa,and the compressive strength is 0.7 MPa.Coefficient of 0.0935W/(m·K).