Initial Evaluation of Foamed Asphalt Stabilization Using Modified Asphalt Cement

With six experienced foamed asphalt stabilization contractors operation in Eastern Ontario, this method of pavement rehabilitation is now commonly used in this part of the province. The quality of foamed asphalt stabilized pavement depends on such factors as the uniformity of compaction achieved in the field, gradation of stabilized material and in particular the content of fines and mixture uniformity. It is typically required that the dry tensile strength should not be less than 300 kPa and for durability purposes, the Tensile Strength Ratio (TSR) should be not less than 50 percent. Lafarge North America in cooperation with Roto-Mill Services Ltd. and Golder Associates has completed a pilot foamed asphalt stabilization project in Ontario using modified asphalt cement. Besides regular quality control/quality assurance testing, additional evaluation of the foamed asphalt stabilization, it included process monitoring, additional compaction testing using nuclear densometer (direct transmission method), sampling of materials and Falling Weight Deflectometer (FWD) testing. The initial results of the evaluation are very encouraging. The compaction on both sections (asphalt and granular pavements) with modified asphalt cement was higher and more uniform than on the section with conventional material. The laboratory testing indicated that the tensile strength and the TSR of the modified material is higher that that of the conventional material. The structural capacity of the foamed asphalt layer with modified asphalt cement was significantly better than that of the layer with the conventional asphalt cement.