Performance-Related Characterization of SBS-Modified Bitumen-Filler Mastics Incorporating Hydrated Lime

Nowadays, road maintenance and rehabilitation strategies represent important budget investments worldwide as a result of the need for suitable pavement structures. The selection of alternative materials for more efficient and durable solutions is therefore imperative through research initiatives and field projects. In response to these requirements, this paper reports the main results derived from an experimental study on asphalt mastics produced with a combined use of styrene-butadiene-styrene polymer modified bitumen and hydrated lime as a partial replacement of limestone filler. The set of five materials considered were subjected to laboratory tests, to characterize the stiffening mechanism and the performance response in terms of fatigue, thermal cracking and permanent deformation. From the results, some benefits and limitations on the use of hydrated lime as a partial replacement of limestone filler were observed, indicating its potential use at optimum filler dosage for pavement locations with warm-to-hot weather as a consequence of the filler stiffening mechanism and its consequences on the elastic response to counteract permanent deformation. Fatigue cracking results suggested detrimental effects on the predicted fatigue lives for very high hydrated lime concentrations, further suggesting the need of an optimum HL below 10% by total mastic volume. Furthermore, the low-temperature results measured through delta Tc values validate substantial improvements in the thermal cracking resistance with the incorporation of HL as a partial replacement of LF.