The Federal Highway Administration (FHWA) Demonstration Project No. 74 has clearly shown that significant differences exist between the volumetric properties of the laboratory designed and plant produced hot mix asphalt (HMA) mixes. The volumetric properties include voids in the mineral aggregate (VMA) and the voids in the total mix (VTM). This project was undertaken to develop practical guidelines for the HMA contractors to reconcile these differences thereby assisting them to consistently produce high quality HMA mixes. The HMA mix design and field test data from 24 FHWA demonstration projects were entered into a database. The data included mix composition (asphalt content and gradation) and volumetric properties. The data were analyzed to identify and, if possible, quantify the independent variables (such as asphalt content and the percentages of material passing No. 200 and other sieves) significantly affecting the dependent variables (such as VMA and VTM).
Based on the preceding work, troubleshooting charts have been constructed to correct and reconcile differences between the volumetric properties of the job mix formula and the produced mix.