超速凝磷酸镁水泥涂层新型喷射工艺及裂缝修复性能研究OA

Aiming at the construction problem caused by the rapid setting and hardening of magnesium phosphate cement(MPC)under the condition of no retarder,this study adopted the new mixing-stirring-spraying integrated spraying construction to carry out the mechanized construction of ultra-rapid setting MPC coating,which effectively solved the bottleneck of jet construction of rapid setting cement coating and reduced the cost of raw materials.Based on this,this paper focused on the influence of spraying ultra-rapid MPC coating on the chloride ion penetration resistance of concrete matrix,and evaluated the improvement effect of ultra-rapid MPC coating on the mechanical properties and chloride ion penetration resistance of cracked mortar members.The results show that after 90 d seawater immersion,the chloride ion content of coated concrete in the depth 0～<5 mm is significantly reduced by 24.8%(mass fraction)compared with that of uncoated concrete,and the chloride ion penetration resistance is effectively improved.The permeability behavior of chloride ion in coated concrete obeys the law of decreasing with the increase of structural depth.In the depth 0～<5 mm,the chloride ion content increases with the increase of seawater immersion age,and gradually tends to be saturated,reaching saturation at 454 d,and the content is 0.193%.The 28 d flexural strength of the cracked concrete members after coating repair is increased by 131.3%,and the chloride ion content in the depth 0～<5 mm is reduced by 12.9%.This study provides a theoretical basis for the application of spraying ultra-rapid MPC coating in the protection,repair and reinforcement of concrete structures in marine environment.