Research on Early Performance Optimization for Magnesium Phosphate Cement Materials in Severe Cold Environment
Aimed at the problems that the hydration of Portland cement commonly used in pavement repair is tending towards stagnation,and the strength is difficult to generate under severe cold environment(-20 ℃),a magnesium phosphate cement is selected which can still hydrate normally under negative tem-perature environment.The effects of water-cement ratio(W/C),borax content,polycarboxylate super-plasticizer content and naphthalene superplasticizer content on the early performance of magnesium phos-phate cement in severe cold environment are studied,and the optimal ratio is given.The results show that the increase of W/C in cold environment enables to reduce the flexural strength and prolong the condensa-tion time,but has little effect on the compressive strength.The borax dosage and strength basically show a trend of increasing first and then decreasing,and the strength performance is better at 5％.With the in-crease of polycarboxylate superplasticizer,the compressive strength shows a trend of increasing first and then decreasing.And the flexural strength shows the same law at 1 h,and then shows a negative correla-tion at the later stage.The content of naphthalene superplasticizer is negatively correlated with strength.Therefore,this paper recommendes to choose the mix ratio of 0.16 W/C,5％borax dosing and 0.4％polycarboxylate superplasticizer dosing in the cold environment.The results of this paper can provide a theoretical support for the rapid repair of airport pavement in the severe cold environment.
severe cold environmentmagnesium phosphate cementpolycarboxylate superplasticizernaph-thalene superplasticizermechanical propertiesworking performances
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