Study on the discreteness of dynamic compressive strength of concrete with different coarse aggregate particle size
In order to study the discreteness problem of dynamic compression test caused by the difference of coarse aggregate particle size,concrete and mortar specimens with the largest particle size of 8 mm,14 mm and 26 mm are prepared,and the stress-strain curves and strain rate-dynamic increase factor(DIF)curves of each sample under different strain rates are obtained through dynamic and static compression tests.In order to more intuitively analyze the problem of test discreteness caused by the difference in coarse aggregate particle size,the particle size coefficient λ is defined as the ratio of the maximum particle size of the coarse aggregate d to the diameter of the specimen D,and the coefficient of variation CV is introduced.Using mathematical statistical methods to quantify the discreteness,obtain the relationship between λ and CV,and intuitively reflect the relationship between the discreteness and the coarse aggregate particle size.The analysis shows that,λ=0.34 is the critial point of concrete material heterogeneity.When the particle size coefficient λ<0.34,the effect of concrete material heterogeneity is not obvious.When λ>0.34,the excessively large coarse aggregate particle size has affected the dynamic response of concrete,and the material heterogeneity is obviously enhanced.This conclusion has guiding significance for the selection of coarse aggregate particle size in future engineering and experiments.
discretenessparticle size coefficientdynamic increase factorconcretesplit Hopkinson pressure bar
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