Measurement Method of Critical Voids in the Mineral Aggregate (VMA) of AC-13 Asphalt Mixture
The voids in the mineral aggregate (VMA) is considered to be the most important mix design parameter which affects the durability of the asphalt concrete mix. This has traditionally been addressed during mix design by meeting a minimum voids in the mineral aggregate (VMA) equirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal of this study is to determine the validity of the minimum VMA requirement versus nominal maximum aggregate size required in Marshell volumetric mix design. The project seeks to fulfill two specific objectives: A. to establish a laboratory method by which the transition of an asphalt paving mixture from sound to unsound behavior may be credibly identified and measured; and B. to derive a predictive relationship relating critical state (e.g., critical VMA) to aggregater elated properties such as nominal maximum aggregate size, gradation, shape, and texture. Specimens were compacted using the Superpave Gyratory Compactor (SGC), conventionally tested for bulk and maximum theoretical specific gravities and physically tested using the Thiaxial creep test system under a repeated load confined configuration to identify the transition state from sound to unsound. AC-13 were classified in the light of fine gradation and coarse gradation. The upper limit gradation, medium value gradation and lower limit gradation of AC-13 asphalt mixtures were tested as the object of study. The results clearly demonstrate that the volumetric conditions of an HMA mixture at the stable unstable threshold are influenced by a composite measure of the aggregate size gradation and by aggregate shape and texture. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures.. Based on the laboratory data and analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate factors (gradation, shape, and texture).
critical VMA AC-13 asphalt mixture measurement method
LI Chuangmin CHEN Chao ZHANG Tianze LI Jian
Department of Highway Engineering, Changsha University of Science and Technology, Changsha, 410076, China
国际会议
北京
英文
2007-08-05（万方平台首次上网日期，不代表论文的发表时间）