Performance Studies On Magnesium Phosphate Cement

Magnesium phosphate cement(MPC) is a New Gelled Material of early-strength andhigh hardness. It mixed up with Magnesium oxide(M) reheating or Magnesium oxideelectrolysis and phosphate or acid phosphate(P) with adjusting admixture accompaniedwith other material according to a certain proportion. It would have The sour alkalineutralizes reaction when mix it with the water with MgNH4PO4·6H2O (struvite)produced as a result. MgNH4PO4·6H2O is extensively used in the repair of the cementconcrete pavement and airstrip with high crystal structure. But the engineeringroadblock is that MPC’s reaction of hydration has a large heat release and it has soquick a reaction that easy to beyond control.At the beginning of this passage, we have do the research of the influence to theMPC’s mechanics characteristics of different ratio of P&M. From this we haveacquainted the composition of MPC which satisfied the feature of early-strength andhigh hardness. In view of the above, we discuss the influence to MPC’s solidificationtime and compressive strength of different retarder and the retarder ways, we alsoanalyse the regular of the varies of the factor. From this, we found an MPC fitconstruction plan and strength requirement. In the end, conbined with the environmentrequirement of MPC, we do the study of the water resistance, frost resistance andsulphate corrosion resistance of MPC. Here’s the conclusion.(1)When the other raw material ratio is settled, if you change the ratio of M/P, thestrength of MPC changes a lot. When the ratio of M/P is:one fourth, MPC’s Mechanicscharacteristics is optima.(2)In MPC made of different acid phosphate, the one have MgNH4PO4·6H2O fit the technical performance of high-early-strength best. But for it’s solidification time is toolong, it can’t fit the require of the engineering construction technology.(3)An moderate of Na2O/P2O5can delay the rate of hydration of MPC. When addmore Na2O/P2O5, the rate of hydration first increase and then decrease. When thecontent of Na2O/P2O5is4%,it has a low influence of Na2O/P2O5to MPC’s3hflexural and compressive strength,and it’s1d,3d flexural and compressive strength hasa obvious improvement compared with the MPC don’t have Na2O/P2O5.(4)When put Pulverized fuel ash in it, the solidification time of MPC has improved,and it still increase when the quantity of ash is mixed. When the quantity mixed up to30%,the solidification time would extend to20minutes. And it also improve thestrength of the cement three days ago in some degree, but it is not obvious in the later.What’s more, it’s not obvious in improve MPC’s freeze-thaw.(5)The raw material of MPC, MgO, NH4H2PO4and MgNH4PO4·6H2O, MAP, can beinsolubilized when put into the water and made the strength decrease. But when mix8034H,it can decrease the dissolution rate and reduce the defect formation. And whenthe content is0.5%, it has the best poor water resistance. It is inconspicuous when theratio increased, but can do an obvious effect to freezing and thawing resistance andsulfate resistance.