Research On Development And Application Technology Of Fast Repair Material MPC For Cement Pavement

The maintenance and repair of cement concrete pavement has restricted its application and development in road engineering,and it is also a hot research topic for road workers.Cracks are the most common diseases of cement concrete pavement.Using ordinary portland cement to repair cracks,it needs a longer health molding time and seriously affects the progress of the project and road traffic.Then the magnesium phosphate material has the advantages of controllable setting time,high strength and small volume change,and can be widely used in crack repair of cement concrete pavement.Therefore,it is very important to study the composition,performance and construction technology of magnesium phosphate fast repair material MPC,giving full play to its rapid and high-strength repair characteristics.Based on the analysis of influencing factors and changing rules of the MPC,s initial setting time,fluidity and strength,the MPC production formula was presented,whose bonding performance,volume stability,durability and construction technology are carried out a comprehensive study.The MPC,s basic performance is closely related to its composition and ratio,its initial setting time extending and fluidity increasing with more P/M and sodium tetra borate;with water-cement ratio and fly ash increasing,the MPC,s initial setting time does not change significantly,but the fluidity of the slurry will be greatly improved;too high level of water-cement ratio and sand-cement ratio is harmful to development of strength,and the use of appropriate amount of fly ash to replace part of the powder material can improve the strength.Based on the basic performance and economic considerations,in the best condition that P / M is 1/4,we can get suitable repair material formula for different types of pavement disease by adjusting the amount of sodium tetra borate,water-cement ratio and the amount of aggregate to control the MPC,s construction performance and mechanical properties,which is MPC-??MPC-??MPC-?? MPC-?.When the pavement has more cracks and almost loses carrying capacity,using the auxiliary repair method with repair material MPC-? or MPC-? has good repair effect and economy;for cracks with a width above 0.6 cm,direct perfusion with MPC-?material can achieve rapid repair requirements;if the width of the crack is less than 0.2cm,it can be repaired by pressure grouting or expansion joints.In the case of crack repair,compared with ordinary Portland cement and fast hard cement SAC,the MPC,s initial strength develops faster,whose strength can reach more than 30 MPa in 2 hours;it has small initial shrinkage and good volume stability,which is only a fraction of the shrinkage of ordinary cement;it has excellent early bond strength and interface performance.MPC has good corrosion resistance in water environment and has excellent resistance to sulfate attack;MPC has a good impermeability,wear resistance and anti-salt capacity.From application situation of the Gansu Maijishan Tunnel project,MPC has a good technical and economic advantages.Therefore,repairing cement concrete pavement cracks by giving full play to the technical advantages of MPC materials,not only can achieve good repair effect,but also can shape and open traffic fast,with good technical and economic benefits.