Thermomechanical Properties of Polypropylene-Based Lightweight Composites Modeled on the Mesoscale Darina Dosta ´ lova ´ , Vratislav Kafka, David Vokoun, Lude ˇ k Heller, Libor Mate ˇ jka, Luka ´s ˇ Kader ˇa ´ vek, and Jan Pe ˇnc ˇı ´k (Submitted April 11, 2017; in revised form July 6, 2017; published online October 3, 2017) A waste-based particle polymer composite (WPPCs) made of foam glass and polypropylene was developed as a low-cost construction material. Thermomechanical properties of the composite, including creep properties of WPPC and polypropylene binder, were examined. By adding a relatively small amount of polypropylene to foam glass (about 2:8 in volume parts), the maximum bearing capacity at room tem- perature of the composite increased from 1.9 (pure foam glass) to 15 MPa. A significant creep strain accumulated during compressive loading of WPPC (5 MPa) in the first 2000 s at elevated temperatures (40, 60 °C). In the study, KafkaÕs mesomechanical model was used to simulate creep strain changes in time for various temperatures. The applicability of KafkaÕs mesomechanical model for simulating creep properties of the studied composite material was demonstrated. Keywords building material, composite, creep tests, mesome- chanical model, thermal insulation 1. Introduction Polypropylene (PP) fibers have been used in civil engineer- ing applications for several last decades. Specifically, PP fibers are used in concrete as reinforcement or as a material compound enhancing cracking resistance in concrete (Ref 1). The fibers are also added to soils in order to reduce the brittleness of soil stabilized by lime (Ref 2). Furthermore, an addition of the fibers is beneficial in asphalts for road construction (Ref 3). Polypropylene might be a waste material and mixed with other materials; it may reduce the cost of the final composite products. Additionally, PP features low thermal conductivity and hence, it is usable as a thermal insulator applicable for low-energy buildings (Ref 4). Mechanical properties of PP can be adjusted by the molecular weight, degree of crystallinity, or the way of processing (Ref 5, 6). In our study, mechanical properties, such as creep behavior, of waste-based particle polymer composite (WPPC) made from PP and recycled foam glass (FG) were examined. The WPPC was designed as a construction material providing both suit- able thermal and mechanical properties in order to become a material of choice for thermal insulation in a humid environment List of symbols General mechanics r ij Stress tensor d ij r Isotropic part of r ij (r = r ii /3) s ij Deviatoric part of r ij (s ij = r ij  d ij r) e ij Strain tensor d ij e Isotropic part of e ij (e = e ii /3) e ij Deviatoric part of e ij (e ij = e ij  d ij e) d ij KroneckerÕs delta E YoungÕs modulus m PoissonÕs ratio l = (1 + m)/E Deviatoric elastic compliance q = (1  2m)/E Isotropic elastic compliance Specific symbols  j Over-bar that relates symbol | to the composite—average in a representative volume element of the composite r Index relating the symbol to the resistent PP c Index relating the symbol to the compliant FG e Index relating the symbol to the elastic constituent of the PP n Index relating the symbol to the inelastic constituent of the PP m r {m c } Volume fraction of the resistant PP {of the compliant FG} in the composite. In part 3, m r {m c } are denoted as V PP {V FG } m e {m n } Volume fraction of the elastic {inelastic} constituent in PP e ij ¢ e ij   e ij d ij e¢ Isotropic part of e ij ¢ e ij ¢ Deviatoric part of e ij ¢ r ij ¢ Stress related to e ij ¢ similarly as is r ij related to e ij d ij r¢ Isotropic part of r ij ¢ s ij ¢ Deviatoric part of r ij ¢ g e , g n Structural parameters of PP Darina Dosta ´lova ´ , Faculty of Civil Engineering, Brno University of Technology, Brno, Czech Republic and Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic; Vratislav Kafka, Institute of Theoretical and Applied Mechanics of the Czech Academy of Sciences, Prague, Czech Republic; David Vokoun and Lude ˇk Heller, Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic; Libor Mate ˇjka and Jan Pe ˇnc ˇı ´k, Faculty of Civil Engineering, Brno University of Technology, Brno, Czech Republic; and Luka ´s ˇ Kader ˇa ´vek, Institute of Physics of the Czech Academy of Sciences, Prague, Czech Republic and Department of Materials, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Prague, Czech Republic. Contact e-mail: dostalova@fzu.cz. JMEPEG (2017) 26:5166–5172 ÓASM International DOI: 10.1007/s11665-017-2967-1 1059-9495/$19.00 5166—Volume 26(11) November 2017 Journal of Materials Engineering and Performance