The Test Research On Critical Voids In The Minerals Of Asphalt Mixture

Voids in the Mineral Aggregate (VMA) of the bituminous mixture is one of the most important parameters of bituminous mixture design and it influences the durability of mixture. The specified minimum VMA can assure not only the enough bitumen content, but also the stability of mixture. At present both Marshall,Superpave and China design method of bituminous mixtures stipulated a minimum VMA according to the maximum nominal size of aggregate. So according to the types of mixture or the content of the coarse and fine aggregate or the types of aggregate gradation, which assured the stability of designing mixture and avoided ruling out economical mixes with acceptable performance properties because of the restrictive VMA, studying the critical VMA of current specification's bituminous mixture and putting forward the minimum VMA have the important values in academic and practical research.Among so many factors influencing VMA, the principal factors are as follows: the maximum nominal size of aggregate, gradation, asphalt content, dust content or particle angularity and so on. The paper has studied influences on VMA of the gradation and asphalt content by orthogonal experiment. An ANOVA analysis of the orthogonal experiment result obtains the predictive model and identifies the significance and quality of the influence of these factors on gradation parameters(CA,FAC,FAF) by SPSS.At present there are four methods for computing VMA. The paper has computed the values of VMA with 4 kinds of computation method for 24 kinds of mixtures, has analyzed the difference of the 4 kinds of computation method and has established the relationship between ? VMA and the product (M) of fine aggregate content and the average water absorption of each kind of mixture. In the end, the paper put forward a proposal for the amends to the VMA.The VMA at which mixtures in fact transition from sound to unsound is...