基于矿料间隙率的SMA混合料设计新法

Modified SMA Design Procedure Based on Voids in Mineral Aggregate

摘要:

根据沥青马蹄脂碎石混合料(SMA)中集料、沥青、空隙率与矿料间隙率(VMA)之间的体积关系，推导了VMA与沥青用量之间的关系;论证了VMA对SMA混合料级配的影响;讨论了VMA与级配之间的关系.由此得出了基于VMA的SMA混合料设计新方法：首先根据技术要求确定VMA的大小，从而得出最佳沥青用量，并可缩小SMA的级配范围，最后在此范围内，采用确定的最佳沥青用量试配3个级配，空隙率最接近目标空隙率的级配即为最佳级配.通过具体混合料设计实例,证明SMA混合料设计新法比常规方法简便、快速、准确、可靠.

Abstract:

Based on the volume relationship of aggregate,asphalt, air voids (Va) and voids in mineral aggregate (VMA)in stone mastic asphalt (SMA),the relationship between VMA and asphalt content is discussed and an optimum asphalt content(OAC)equation is deduced.Besides,the influence of VMA on the gradation of SMA is analyzed.According to the deduced relationship of VMA,OAC and gradation,a modified SMA design procedure is proposed.First,VMA is determined as the technology required,and then both the OAC and a more accurate gradation range based on the determined VMA are obtained.Finally,three trail gradations are selected according to the narrowed gradation range;accordingly,specimens using the OAC are compacted.Of the three gradations,the one of the closest Va to 4% is selected as the optimum gradation.A case study is conducted and results show that the modified design procedure for SMA is quicker,simpler and more reliable than conventional design procedures for SMA.