Creep behaviour of FRP-reinforced polymer concrete C.M.L. Tavares, M.C.S. Ribeiro, A.J.M. Ferreira * , R.M. Guedes Faculdade de Engenharia, Instituto de Engenharia Mec^ anica e Gest ~ ao Industrial, Universidade do Porto, Rua do Barroco 174, 4465-591 Lec ßa do Balio, Portugal Abstract Polymer concrete is a kind of concrete where natural aggregates such as silica sand or gravel are binded together with a thermoset resin, such as epoxy. Although polymer concretes are stronger in compression than cementitious concrete, its tension behaviour is still weak. The reinforcement of polymer concrete beams in the tension zone with pultruded profiles made of epoxy resin and glass fibers are a good compromise between stiffness and strength. In this paper it is reported an investigation of the creep behaviour of polymer concrete beams reinforced with fiber-reinforced plastics (pultruded) rebars. Four-point bending creep test were performed. An analytical model was applied to verify the experimental results. Ó 2002 Elsevier Science Ltd. All rights reserved. Keywords: Creep; Polymer concrete; Composites; Reinforced concrete 1. Introduction In polymer concrete a resin binds natural aggregates. Common thermoset resins are polyester and epoxy while natural aggregates can be of various nature, such as silica sand. Like any other type of thermoset resin, catalyst or hardeners are added to the resin prior to mixing and casting of such polymer concrete. In poly- mer concrete, water is not present at all, unlike cement concrete where water play a major role. Water or moisture can damage the hardening process of the resin [1,2]. Polyester resin is the most common due to low price and good corrosion properties. However, curing of polyester must be well controlled in order to maintain good workability for a high viscous polymer concrete. Polymer concretes have high compressive strength, good corrosion resistance, low permeability and fast setting times [3]. These characteristics allow the continuous, although slow, increase of polymer concrete in civil construction industries. Polymer concrete have similar mechanical behaviour to cement concrete. Compressive strengths of 100 MPa are common in polymer concrete. However, like cement concrete, its tensile strength is much lower. Therefore some reinforcement is needed in the tensile zone. Several authors have used steel rebars for reinforced concrete and also glass or carbon short fibers to reduce cracking [4–7]. In this work pultruded rods were used. These rods are manufactured from polyester resin and glass fiber. Polymer concrete is rate- dependent, due to the polymeric nature of its matrix. Creep tests were performed on polymer concrete beams reinforced with composite rods. It is reported the ex- perimental results of such creep tests and conclusions about their performance is discussed. 2. Testing set-up Polymer concrete with 80% (in mass) of foundry sand and 20% epoxy resin was used as the basic material. This formulation corresponds to an optimised result from previous research [9–15]. Foundry sand has rather uni- form granulometry with a mean diameter of 245 lm. The mechanical properties of this polymer concrete are presented in Table 1 and the mechanical properties of the pultruded rods are presented in Table 2. Beams with dimensions 296  30  50 mm were casted, with 4 mm pultruded rods reinforcement, as shown in Fig. 1. 3. Static testing Static tests are needed in order to check the ulti- mate load. In this case we choose a failure by bending. Three point bending tests were performed at a speed of * Corresponding author. E-mail address: ferreira@fe.up.pt (A.J.M. Ferreira). 0263-8223/02/$ - see front matter Ó 2002 Elsevier Science Ltd. All rights reserved. PII:S0263-8223(02)00061-2 Composite Structures 57 (2002) 47–51 www.elsevier.com/locate/compstruct