Research On Self-healing Properties Of Inner-mixed Type CCCW Concrete Under Different Environmental Influence Factors

For key impermeability and anti-leakage projects such as tunnels,anti-corrosion projects,hydropower nuclear power plants,sewage treatment,and various civil and hydraulic engineering,ordinary concrete materials are subject to many environmental factors in the application engineering,resulting in cracking of the concrete,resulting in concrete structural mechanical properties and anti-seepage,performance and durability are severely reduced,causing engineering safety accidents.Cementitious capillary crystalline waterproofing materials(abbreviated as CCCW)is a powdery rigid waterproof material mixed with special active chemicals.The material has unique self-healing ability strong waterproof and impermeability,and is green,environmentally friendly,and construction convenience and other advantages.Therefore,CCCW is added to ordinary concrete to improve the performance of concrete.The active material in CCCW is penetrated into the concrete through the micro cracks and capillary channels in the water as a carrier,and the hydration of the concrete is stimulated to penetrate and crystallize to repair the cracks and capillary channels In order to effectively improve the compactness and mechanical properties of the concrete structure,to achieve permanent waterproof,and to resist the corrosion of reinforcing steel and enhance the durability of the concrete structure.Domestic research on the application of CCCW in engineering is still in its infancy,mainly because the mechanism and performance characteristics of CCCW are still lacking a large amount of experimental data and theoretical analysis to support the practical application of engineering,and the price is relatively expensive.In this paper,two different brands of CCCW materials are used to study the self-healing ability and impermeability of the CCCW concrete with different prefabricated cracks under different environmental factors.The self-healing effect of the self-healing rate of the inner-mixed type CCCW concrete was analyzed by experimentally testing the mechanical property self-healing rate of the sample and the secondary anti-seepage pressure.The test parameters involved are: curing conditions,crack width,age,concentration of soaking solution,amount of dispersant,and number of impermeability tests.Based on the comparison of the benchmark group and the theory of existing research results,combined with the results of this test,the mechanism of repairing through cracks of two types of inner-mixed type CCCW concrete was summarized to determine the best conditions for self-healing of concrete.In addition,through microscopic analysis,using scanning electron microscopy,X-ray fluorescence spectroscopy,X-ray diffractometer,etc.to determine the phase composition,number of crystals and micro-structure morphology of the internal concrete.Through experimental research,it was found that:(1)The standard curing effect of the mixed CCCW concrete is the best,and the repair performance and impermeability are obviously better than the benchmark group.The larger the width of the concrete cracks,the less favorable the self-healing.(2)The inner-mixed type CCCW concrete soaked in ammonium sulfate,chromium chloride,lead nitrate and other solutions has strong corrosion resistance.The ability of self-healing at different ages is related to the concentration of the chemical solution,a certain concentration of chemical solution can promote the self-healing of concrete cracks,and the increase of the concentration increases the adverse effect.(3)The two dispersants can enhance the dispersion performance and crack self-healing ability of the concrete under the appropriate dosage.SHMP decreases the mechanical properties of the concrete with the increase of the dosage,and the retarding time increases;TEOA can promote the hydration of concrete to enhance the mechanical properties,and the blending amount has little effect on self-healing performance.(4)Microscopic analysis shows that the inner-mixed type CCCW concrete has a certain ability to adsorb heavy metals,and the aqueous medium is conducive to exciting CCCW active substances to form crystals,and its main component is calcium carbonate or ettringite,these crystalline substances are the key factors that can repair cracks in concrete.