Experiment On Sulfate Corrosion Resistance Of Concrete Modified By Calcined Layered Double Hydroxides

There are many factors affecting concrete durability,of which sulfate erosion is an important aspect.It's destructive and the mechanism is complex.Generally speaking,there is relatively little research on concrete resistance to sulfate attack.Using layered double hydroxides improve the concrete durability is a new research field.However,there is little research on concrete resistance to sulfate attack by using layered double hydroxides.This paper appointed LDOs as the mainly experimental material.The mechanism of LDOs absorbing sulfate ion was studied by the means of microscopic analysis,and the permeation law of sulfate ion in concrete mixing LDOs was analyzed,and then the resistance to sulfate attack of concrete mixing LDOs and carbonation resistance were studied.The main research results are as follows:(1)LDOs can absorbing sulfate ion in solution and reconstruct its laminate structure during absorbing.With XRD,SEM and EDS,it demonstrates that LDOs can effectively adsorb sulfate ion in cement hydration environment.(2)The fitting curve of absorbing sulfate ion capacity with the content of LDOs in solution is obtained by barium sulfate titration.By determining the content of water soluble sulfate ion in each layer of concrete mixing different contents of LDOs,it is proved that LDOs can delay the infiltration of sulfate ion in concrete.(3)It can be concluded that LDOs can reduce the volume expansion caused by sulfate attack.The strength test of concrete under sulfate attack shows that LDOs can effectively delay the strength degradation of concrete,and the effect is obvious when the content of LDOs is 2% of cement.(4)It demonstrates that LDOs can absorbed carbon dioxide in cement paste and significantly improves carbonation resistance of cement-based materials.