未加沥青矿料V_(MAa)物理模型构建与应用

Building and Application of V_(MAa) Physical Model of Mineral Aggregate Without Adding Asphalt

为研究矿料性状与级配对矿料间隙率的影响规律与作用机制,发展沥青混合料矿料级配设计理论,首先采用数学建模方法,基于一定假设,分别建立了骨架空隙、骨架密实和悬浮密实型级配的未加沥青的矿料间隙率(V_(MAa))物理模型;根据模型,建立了一种矿料间隙率(VMA)排序的早期诊断技术,并提出了一种骨架密实型级配设计新方法。其次,通过沥青混合料制件试验,对模型揭示的规律性进行检验。研究结果表明:未加沥青矿料的矿料间隙率等于普遍意义上的粗料间隙率和细料间隙率的乘积;所建模型联合揭示了V_(MAa)的变化规律,即随着粗细分界粒径通过率的增大,V_(MAa)先减小(骨架空隙级配),当减小到一定程度(骨架密实级配)后开始增大(悬浮密实级配),呈现两边不对称的V形趋势,试验验证效果较好;粗、细料的间隙率,密度及细料用量等参数对V_(MAa)分别有不同的方向性影响,与级配类型有关;级配曲线设计应分为粗料和细料两段进行,在级配设计的初始阶段,无需制件,仅根据拟定级配的粗、细料间隙率、密度及粗、细分界粒径通过率等数据信息就能预估VMA的排序;路面中常用的沥青混合料如AC-25可设计成骨架密实级配。

In order to investigate the effect laws and mechanisms of mineral properties and gradation on voids in mineral aggregates and develop the gradation design theory of asphalt mixture, the method of mathematical modeling was firstly adopted, and physical models were established including framework-void, framework-dense, and suspend-dense gradation of voids of mineral aggregate without adding asphalt （VMAa） based on certain assumptions. According to the models, an early diagnostic technique was built to forecast the order of sizes of the voids in mineral aggregate of asphalt mixture （VMA）, and then a new method to design the framework-dense gradation was put forward. Secondly, by the test of making specimens of asphalt mixture, the regularity revealed by the models was verified. The results show that the value of VMAa is equal to the product of the values of the void of coarse aggregate and the void of fine aggregate in universal meaning. The established models reveal the change law of VMao, which is with the increase of the passing rate of the demarcation particle size between coarse and fine aggregate, the value of the VMaa firstly decreases （for framework-void gradation）, and then, when it reduces to a certain value （for framework-dense gradation）, it increases （for suspend-dense grade）, which presents an asymmetric V shape and is well verified by the test. Parameters such as voids in aggregate and density of coarse and fine aggregate as well as dosage of fine aggregate have different directional influences on VMAa, and the influences are related to the gradation type. Gradation curve design should be divided into two sections, which are coarse aggregate design and fine aggregate design. In the initial stage of gradation design, only according to the voids in aggregate and densities of coarse and fine aggregate which come from proposed gradations as well as the passing rate of demarcation particle size between coarse and fine aggregate, the order of VMa can be forecasted without making asphalt mixtures specimens and the common asphalt mixture in road like AC-25 can be designed as framework-dense gradation.