Computed tomography: an evaluation of the effect of adding polymer SBS to asphaltic mixtures used in paving

This work applies the Computed Tomography (CT) technique to the study of asphaltic mixtures to which polymer has been added. An evaluation has been made of the effect of adding Brazilian produced polymer SBS (styrene-butadiene-styrene), to the asphaltic mixtures used in paving. Laboratory mechanical tests and nondestructive testing (NDT) of cylindrical specimens have been made. Three mixtures were prepared for the purpose of this study, all containing 5.4% of asphalt RASF (propane deashalting). One of the mixtures contained no polymer, while the other two were made with 7 and 5% of the SBS polymer. Investigations of Brazilian pavements have shown that cracking is the most important defect due to fatigue in the asphaltic contained overlay. Preliminary results of mechanical tests show that the polymer additive Favorably enhances performance of the mixtures. It may be noted that adding polymer SBS to the asphaltic mixture used in paving increases the percentage void. Crack growth in specimens of asphaltic mixtures to which polymer has been added displays the same behaviors as that in specimens in which polymer has not been added. (C) 2000 Elsevier Science Ltd. All rights reserved.