Energy-efficient polymer/bitumen roofing materials formulated with non-encapsulated beeswax phase change material

Abstract

With the aim of overcoming the drawbacks involved in PCM encapsulation and taking into account the potential of beeswax as bio-PCM, the main objective of this work is to develop novel energy-efficient roofing materials for building applications by its direct inclusion. These materials are formulated with bitumen (B), styrene butadiene styrene copolymer (SBS) and beeswax (BW) as bio-based phase change material. To that end, the effects of possible interactions between B compounds and BW on thermal storage capacity and technological characterization were firstly evaluated on binary B/BW blends. Afterwards, leakage tests conducted on ternary B/SBS/BW blends revealed that form-stable materials (with no BW leakage) can be manufactured with a maximum BW concentration of 30 wt%. Thus, the prototype roofing material composed of 61.6 wt% B, 8.4 wt% SBS and 30 wt % BW shows excellent thermal stability (no weight loss up to ca. 200 ◦C) and meets the technological requirements specified by ASTM D8051 for wax-modified asphaltic roofing products. In addition, the selected roofing material displays high thermal storage capacity (ca. 50 J/g) for a long period of time (at least, for 300 heating/cooling cycles), which is reflected in the results derived from the indoor thermoregulation tests conducted in a climatic chamber. Interestingly, the tests conducted on a reduced-scale isolate room indicated a percentage reduction in the heat needed to be removed from the room of 9.3 % when comparing the prototype roofing material with the commercial SBS bituminous binder.