The Influence Of Compositions And Process Conditions On The Performance Of Concrete Structure Repair Mortar

Polymer modified cement mortar with excellent performance, is the main direction of research for repair materials of concrete structure.In this paper, the best mix proportion of repair mortar was obtained through analyzing the impacts of the constituent materials on the performances of repair mortar. The effects of preparation process, construction process and maintenance process on the performance of repair mortar were studied.The research results show that:The addition of polycarboxylate superplasticizer can reduce the water cement ratio of mortar effectively and improve compressive strength, flexural strength and tensile bond strength to some extent, and the suitable dosage was 1.4%.With the addition of dispersible polymer powder, the flexural strength and tensile bond strength of mortar first increased and then decreased, but also improved the compressive strength of mortar in low dosage, enhancing the water retention of mortar, prolonging the setting time of mortar, improving the workability of mortar, and its appropriate dosage range was 2.0%.The cellulose ether can enhance the water retention of mortar significantly, improving the construction performance of fresh mortar. The flexural and tensile bond strength with the increase of cellulose ether content increased first and then decreased. Its suitable dosage was 0.05%. Defoaming agent can eliminate excess mortar harmful bubble, and the suitable dosage should be 0.06%.The repair mortar had long operation time and high water retention rate and small dry shrinkage value, and the compressive strength, flexural strength and tensile bond strength was 71.2 MPa, 15.1 MPa, 2.88 MPa in the 28 d. Its performances was far more than A type mortar requirements of JG/T 336-2011.Mixing the dry materials in advance was useful of repair mortar mixed uniformly. Feeding order of mixing mortar was premixed dry materials, water, water reducing agent, defoaming agent. The suitable mixing time was 3min.Before the construction, repair mortar surface should keep dry because of excessive water having a negative impact on bonding properties of the repair mortar. The bonding properties would be better if coating repair paste interface agent. The best curing method of repair mortar was to keep wet firstly and dry again, because wet curing was advantageous to the cement hydration and dry curing was advantageous to the polymer film. Performances of repair mortar were excellent in the practical application, and good to meet the requirements of the actual repair work. The mortar was applied to repair the damaged actual road shoulder edge, and repair effect was very good.