1373046 - Deconvoluting the mechanisms of thermal degradation and oxidative aging in polymer-modified asphalt binders

Polymer modification has direct benefits in enhancing various performance attributes of asphalt binders. However, the aging of such binders during pavement service life is inevitable and leads to various pavement distresses. There is very little information in the literature that explores the different physicochemical mechanisms of aging in polymer modified binders (PMB) when considering the asphalt binder and polymer components individually. In particular, this study attempts to understand and deconvolute the aging of PMBs and discretize the thermal degradation and oxidative effects of aging in PMBs. Six binders, including two unmodified binders and four SBS-modified binders with two polymer contents (3% and 4.5% binder wt.) were aged using two different protocols. The first protocol involved aging binders in a conventional oven under an air blanket at 100°C and atmospheric pressure for two days, four days, and six days separately. The second protocol involved aging binders under a nitrogen blanket with other conditions similar to the first protocol. The aged binders were tested using thin-film poker chip ductility and tensile strength, frequency-temperature sweep testing, and FTIR spectroscopy. The results from the study indicated that the effect of thermal degradation of polymers was minimal and the loss of ductility during aging can be mainly attributed to the effect of oxidation on binder and polymer components.