Polypropylene Fibers as Reinforcements of Polyester-Based Composites

Effects of gamma radiation and the polypropylene fibers on compressive properties of polymer concrete composites (PC) were studied. The PCs had a composition of 30？wt% of unsaturated polyester resin and 70？wt% of marble particles which have three different sizes (small, medium, and large). The PCs were submitted to 200, 250, and 300？kGy of radiation doses. The results show that the compressive properties depend on the combination of the polypropylene fiber concentration and the applied radiation dose. The compressive strength value is highest when using medium particle size, 0.1 vol% of polypropylene fibers and 250？kGy of dose; moreover, the compressive modulus decreases when increasing the particle size. 1. Introduction Polymer concrete (PC) is a composite material formed by combining mineral aggregates with a thermoset resin. In its elaboration several parameters must be taken into account, such as resin type, initiator, and accelerator concentrations. The unsaturated polyester resin (UPR) is the most widely used due to their balanced mechanical and chemical characteristics, its ease of handling, and low cost; for its polymerization, 2？wt% of methyl-ethyl-ketone peroxide (MEKP), as initiator, and 0.5？wt% of cobalt naphthenate as accelerator are normally used, with at least 40？wt% of styrene. The composition of polymer concrete is determined by its applications especially loading stress levels and ability to resist corrosive environment. PC is increasingly being used as an alternative to ordinary Portland cement concrete (PCC) in many applications, such as finishing work in cast-in-place applications, precast products, highway pavements, bridge decks, waste water pipes, and even decorative construction panels. In the last 40 years polymer concrete has made tremendous progress and continues to be very promising materials for a wide range of new and innovative applications. Moreover, the use of polymers should be well considered to guarantee better performance and improved sustainability [1–3]. Improvement on mechanical strength and chemical resistance is basic advantages of polymer concrete in comparison to ordinary Portland cement concrete (PCC). Three to five times on the compressive strength, high values for tensile strength (20？MPa), and flexural strength (50？MPa) are still an outstanding advantage of polymer concrete [3, 4]. Mechanical properties of polymer concrete depend on the type of resin and mineral aggregates. In the case of the last, higher specific surface means higher mechanical values, for example, (a) polymer concrete with clean sand