Experimental Study On Modification Of Magnesium Oxychloride Cement With Additives

As a new type of inorganic cementitious material,magnesium oxychloride cement has attracted more and more attention.Although many factors affect the properties of magnesium oxychloride cement,such as hydration mechanism and mix ratio of magnesium oxychloride cement,the poor performance of water resistance and volume stability in the practical application of magnesium oxychloride cement material is still poor.Not good improvement.In this paper,the effect of magnesium oxychloride cement on the properties of magnesium oxychloride cement is investigated by the modification of the admixture.The admixture used in the modification test is poplar wood powder and fly ash.Admixtures are tested in the form of separate addition of magnesium oxychloride cement,and the effect of additives on their properties is obtained.The concrete results are as follows:(1)It is determined that when the mole ratio is MgO:MgCl2=7:1,the dry compressive strength of the magnesia cement material reaches the maximum and the magnesium oxychloride cement has the best water resistance.When the n value of MgO:MgCl2=n is greater than 7,the resistance to moisture and halogen resistance of the MgO cement material can also be better.When mole ratio of magnesium oxychloride cement is MgO:MgCl2=7:1,it is better to determine mole ratio MgO:MgCl2=7:1 as the reference ratio for subsequent experiments.(2)By adding wood flour alone,the peak value of hydration heat release of magnesium oxychloride cement can be reduced.When the particle size of wood flour is 20 to 40 and the mixing ratio is controlled between 20%-30%,the strength of magnesium oxychloride cement material is improved.(3)When the admixture is added to fly ash alone,the hydration heat peak of magnesium oxychloride cement is worth reducing.When the proportion of fly ash is up to 25%,it has a good effect on improving the strength and water resistance of magnesium oxychloride cement.When the mixing ratio is between 20%and 30%,the volume stability of magnesium oxychloride cement can be effectively improved.The results of this study provide an important basis for further study of magnesium oxychloride cement materials.