Design and Performance Study of Rapid Repair Cement Mortar Composition for Roads
The effects of water-cement ratio,sand-cement ratio and the dosage of retarder on setting time,compressive strength and bonding properties of Road Repair Mortar(RRM)prepared by ultrafast hard cement are studied by orthogonal test.The dry shrinkage,toughness and sulfate resistance of RRM are tested to evaluate the durability of RRM,and the influence mechanism is discussed based on the micro-morphology and pore structure.The results show that the main factors affecting the setting time,mechanical properties and bonding properties of RRM are the dosage of retarder,water-cement ratio and sand-cement ratio respectively.Considering the mechanical properties and bonding properties of mortar,the optimal ratio of RRM is recommended as follows:water-cement ratio is 0.32,sand-cement ratio is 1.5 and retarder content is 0.3％.Under the optimal ratio,the 28d shrinkage rate is 0.0176％,which is 88.72％lower than the control group with lower cracking risk.Compared with the control group,the bending pressure increases by 37.5％,and the toughness is improved.The compressive resistance,flexural resistance and corrosion resistance are 1.04 and 1.05,respectively,and the sulfate resistance is improved.SEM and pore structure analysis show that with the growth of age,the internal structure of RRM tends to be complete and dense,the pore size distribution is more uniform,and the properties of mortar are improved.
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