Performance Comparison And Microstructure Evolution Of ASC In Different Regions

Based on aeolian sand concrete(ASC)that 40%of river sand quality replaced by aeolian sand as the main material,this paper has carried out two kinds of macro tests:unconfined compressive strength test and clear water freeze-thaw cycle test,supplemented by dynamic particle analysis test,particle grading test,X-ray diffractometer analysis test,NMR test and nano indentation test,combined with grey theory and other analysis methods Research on:1.According to the fineness modulus of aeolian sand,three kinds of aeolian sand concrete are divided into three categories:A,B and C.Among them,the c-asc has the highest compressive strength and little difference from the ordinary concrete(OC);combined with the analysis of nuclear magnetic resonance technology,it can be seen that the internal pores of the C-ASC are the least compared with Class A and class B,with the most small holes and the least large holes in the pore distribution.2.In the freeze-thaw cycle test,it is more accurate to determine the durability by using the relative dynamic modulus of elasticity.Under the same water cement ratio,the frost resistance of C-ASC is the best,and the difference between the frost resistance of class C-ASC and that of OC is not significant.It can be seen from the analysis of pore diameter that it is due to the largest number of pores and the smallest variation of small pores in the test.When the fine aggregate is the same,the frost resistance of C-30 than that of C-20 and C-40,and the analysis pore because it has the most small holes and the smallest change of large holes;3.Nano indentation tests show that the elastic modulus and hardness decrease in the ITZ of ASC after freezing and thawing cycles,because the decrease of CH influences the instability of HD C-S-H gel and leads to transformation LD C-S-H gel in the interfacial transition zone.4.A grey system model is established based on the grey entropy relation between the distribution of pore size,the distribution of HDC-S-H gel and the distribution of CH and the dynamic elastic modulus of ASC.The relative error between the predicted value of ASC durability and the actual value is 4.75%.