The Performance Study On Crack Repair Materials In Severe Cold Area Marine Concrete

Marine concrete is in a worse environment than inland.Ion erosion,changes in dry and wet conditions,low temperature freezing and thawing cause it to be prone to surface damage and cracking,which requires repair.Commonly used marine concrete crack repair materials are mostly organic resins,which have problems such as high price and aging.The cost of crack repair materials prepared by compounding inorganic gelling materials and organic substances is relatively low,which is a trend of the industry development.In this study,quartz stone powder,dispersible latex powder,basalt fiber,and additives,they were used to improve the performance of sulphoaluminate cement-based crack repair materials.Among them,the defoaming agent,water repellent agent,polycarboxylic acid water reducing agent and retarder are used as the admixture.Studies have shown that with the increase in the amount of dispersible latex powder,the setting time of crack repair materials gradually increases,the fluidity decreases,the tensile bond strength increases,the compressive strength decreases,the flexural strength increases first and then decreases,and the hardened micro-expansion significantly improved,dynamic elastic modulus significantly reduced,abrasion resistance increased.And it can significantly improved the resistance to chloride ion penetration,the resistance to sulfate attack and the resistance to single-sided salt freezing are significantly improved.The its content should be controlled at about 1%of cement quality.Basalt fiber improves the performance of crack repair materials for marine concrete better than glass fiber and wood fiber.With the increase of basalt fiber content,the dry shrinkage of crack repair material is significantly improved,and the flexural strength and tensile strength of 1d,3d,and 28d are all significantly improved.The bond strength is significantly improved too.The water reducing agent can effectively adjust the fluidity of crack repair materials.When the amount of water reducing agent is controlled at 0.4%of the cement mass and the citric acid content is controlled at 0.04%of the cement mass,the mechanical properties of the repairing material remain relatively reasonable within range.When the amount of latex powder and basalt fiber is 1%of the cement,and the appropriate amount of quartz stone powder,water repellent,defoamer,water reducer,retarder,etc.,the compactness of crack repair material is better,28d resistance The flexural strength can reach 11.3 MPa,the compressive strength can reach 62.35 MPa,the tensile bond strength exceeds 1 MPa,the dynamic elastic modulus is less than 8 GPa,the micro-expansion rate of0.1%or more is maintained during the hardening process,and the chloride ion penetration test flux is only 140.38C,the corrosion resistance coefficient of the saturated sulfate solution after150 dry and wet cycles is still over 90%,and after 28 cycles of single-sided salt freezing,the mass loss is only 53.5 g/m~2.In this study,dispersable latex powder and basalt fiber were used to modify sulphoaluminate cement to prepare crack repair materials.It has the advantages of micro-expansion,low elastic modulus,high durability,etc.,and can meet the actual engineering requirements of marine concrete repair in cold regions.