Effect Of Calcium Carbonate Whisker On Mechanics And Durability Of Aeolian Sand Concrete

In order to effectively reduce costs and use local materials in the construction of sand areas in the west of Inner Mongolia,we can make use of the abundant aeolian sand resources in desert areas to prepare concrete materials for engineering.In this experiment,60% aeolian sand is used to replace river sand,and the optimum amounts of calcium carbonate whisker for obtaining whisker toughened aeolian sand concrete was analysed by blending different amounts of calcium carbonate whisker,conduct research on the strengthening and toughening mechanism of calcium carbonate whisker on aeolian sand concrete,establish the mathematical model of strength change with age of aeolian sand concrete toughened by whisker.based on the experimental results of freeze-thaw cycle failure of salt solution,this thesis explores the durability change law of whisker toughened aeolian sand concrete,establish the durability life evaluation model of whisker toughened aeolian sand concrete under freeze-thaw damage of salt solution,that provides a scientific basis for the practical application of aeolian sand in the sand area of western Inner Mongolia.Experimental analysis can obtain the following conclusions:(1)Through compressive strength,splitting tensile strength test,nuclear magnetic resonance test and scanning electron microscope test,it can be found that calcium carbonate whisker has an obvious effect on the early age strength of aeolian sand concrete.Calcium carbonate whisker can improve the internal pore structure enhance the mechanical properties of aeolian sand concrete.The content of whisker with the best comprehensive mechanical properties is 0.15%,and the mathematical model of strength change with age is in good agreement with the experimental data,which provides a strong basis for practical engineering application.(2)The whisker group with the best comprehensive mechanical properties(F60J15)and benchmark group(F60J0)were selected for chloride salt freeze-thaw test.It can be found that the damage and deterioration of the two groups of aeolian sand concrete are stronger with the increase of the concentration of chloride salt solution,while whisker group with improved pore structure due to appropriate amount of calcium carbonate whisker,and the maximum depth of chloride salt erosion in the whisker group is lower than in the baseline group.The pore structure of two groups of aeolian sand concrete after 200 freeze-thaw cycles was observed by scanning electron microscope test,the internal damage degree of whisker group is significantly less than that of reference group,therefore,whisker group shows better frost resistance in chloride salt solution.(3)Similarly,the whisker group with the best comprehensive mechanical properties and benchmark group were selected for sulfate freeze-thaw test.It can be found that the damage and deterioration of the two groups of aeolian sand concrete are also increasing with the increase of the concentration of chloride salt solution,however,the damage of sulfate solution is lower than that of chloride solution,and the whisker group also showed better frost resistance than the reference group in sulfate solution.(4)The same experimental groups were selected for composite salt freeze-thaw test.It can be found that it is not the higher the concentration of the salt solution,the stronger the damage to the aeolian sand concrete.Due to the presence of sulfate in the compound salt,it inhibits to a certain extent the destruction of the chloride salt,thus reducing the overall damage to the concrete,and 20 times of composite salt solution showed stronger damage.Enhanced intrusion of sulphate in the composite salt solution was found after testing the test group by XRD,and the whisker group also showed better frost resistance of composite salt.And life prediction using the model for test groups under the three most damaging operating conditions working conditions.