Study On Effect Factors Of Autogenous Healing Of Concrete

Concrete with its many advantages widely used in the areas as water conservancy construction, but the cracks widespread existed in the concrete structure, reduce the function of the structure and the safety. Concrete as one of excellent performance building materials, have a certain capacity for the repair of cracks, that is, the autogenous healing of concrete cracks, the paper tried to study on the mechanism of concrete cracks autogenous healing, and the factors of concrete cracks autogenous healing.Various impact factors of autogenous healing of concrete cracks were analyzed in the paper. Including fly ash,silica fume,the width of cracks and conservation conditions. Using scanning electron microscopy (SEM),X-ray diffraction analysis (XRD) to analyze hydration process and hydration product in the crack of different concrete mix and different age. And make use of Gray correlation calculation and GM (1, N) model to analyze effect factors of autogenous healingThe results show that the pure cement samples, after the autogenous healing of cracks, the cracks splitting the highest tensile strength, split tensile strength of the concrete samples with fly ash have a great development in the latter part of autogenous healing of cracks and can be achieved more than 30 percent of the splitting tensile strength that concrete samples without cracks have. Concrete with silica fume, in the early part autogenous the healing splitting tensile grow obviously, but the silica fume have little help for the splitting tensile strength in the latter part. The concrete with cracks width between 0.30mm～0.50 mm have a better healing effect, the splitting tensile strength can reach a certain level. In addition, water is the key factor of concrete autogenous healing, the effect of autogenous healing when the concrete sample conserved in water is distinct higher than the general conservation.The main chemical reaction of autogenous healing is the cement hydrate second time, create C-S-H and Ca(OH)₂crystal, Ca(OH)₂ continue to work with the reaction of CO₂ in water create CaCO₃ crystal. Gray correlation calculation and GM (1, N) model analyze effect factors of autogenous healing, the result show that the concrete unit volume of cement consumption is the most important factor of autogenous healing in the early time of autogenous healing is the width of crack, the fly ash is the important factors in the latter part of autogenous healing.This article described the existing problems of autogenous healing, and prospect the direction of future research.