Bio and waste-based binders with hybrid rubberized-thermoplastic characteristics for roofing

Abstract

Non-bituminous binders with sustainable characteristics have been developed as potential roofing materials. A vegetable colophony rosin ester, waste cooking oil, waste crumb rubber and a blend of recycled high-density polyethylene (HDPE) and polypropylene (PP) have been used for binder formulations. Rheological, calorimetric and technological characterizations have been performed to assess the compatibility among binder components and optimal compositions. Additionally, thermal conductivity, heat capacity and solar radiation tests have been performed on selected non-bituminous and bitumen-based binders. Solar radiation experimental set-up has been simulated by Computational Fluid Dynamics (CFD) in order to get a deeper insight into heat transmission mechanisms involved. A binder formulation composed of 40 wt% maleic-modified rosin ester, 32 wt % waste oil, 20 wt% crumb rubber and 8 wt% recycled HDPE/PP blend has shown suitable mechanical properties and solar behaviour for roofing materials. The use of recycled thermoplastics and elastomers imparts material with a hybrid character, showing enhanced flexibility and softening points, respectively, at low and high inservice temperatures. Its solar behaviour is comparable to that of the modified bitumen, with a similar heat absorption from Sun (about 30 %) but lower heat storage capacity at ambient temperature.