Research Of Repair Materials Of Cement Concrete Pavement In Frost Zone

With the sharp increase of volume of traffic and the overloading of vehicles, theroad surface was severely damaged and cements concrete pavement need large range ofrepair. Especially in the frost zone, permafrost thaw deposit and frosting heavingdeformation make the pavement more damaged. In this paper, the magnesium phosphatecement (MPC) as the main body, through optimization-design of the mixture ratio, theresearch on mechanical property, durability and other related property of repairmaterials used in the cement concrete pavement. At the same time, several ratio ofrepairing material and its applications environment are got.The results show that there is a proper ratio of magnesia and phosphate in the MPC,it is related to the surface state and the calcined heat of magnesia; the optimumproportion of magnesia and phosphate is 2.5:1 in this paper. The hydration product'smicrostructure of MPC which was added the fly ash is constituted by rod-like structure.When 5% of the fly ash was insteaded of by coarse whiting in MPC which added highvolume fly ash, the fluidity and early strength of MPC are increased. The addition ofwater reducing agent can also increase the fluidity, but it can cause significantlydecreased of early strength. Adding microscopic magnesium chlorate in MPC canimprove water-resistance of MPC, it also makes the strength of MPC under the standardcuring conditions be similar to nature conservation condition. When MPC was cured inwater for 28d, the hydration products of MPC is changed and fibrous crystals aregrowing on the surface.Abrasion resistance of MPC is equality to high strength ordinary cement mortar andabrasion value of MPC decreases by more than 40 % between 7d and 28d. MPC repairmaterial shows well in the resistance of dry shrinkage. MPC whose phosphates waspotassium dihydrogen phosphate always keeps the inflation trend in 28d and in the enddrying shrinkage rate has reached -500×10-6.The addition of coarse whiting can increasethe frost resistance of MPC and its strength loss is less than 10% after 100 cycles ofdeicer-scaling. The hydration products'microstructures of MPC are different when itwas in the different freeze-thaw environments. Adhesion strength of several types ofMPC which were studied in this paper is all above 3.0MPa and the amount of mineraladmixture is the main cause which affects the adhesion strength. Although themicrostructures of these MPC are different, there are no new substances through theXRD analysis.