Creep Studies of Polyester Polymer Concrete under Flexural Loading

The creep of unsaturated polyester/styrene polymer concrete (PC) under flexural loads was investigated using two PC systems with different resin contents, as well as the unfilled resin* Measurements were taken at temperatures, ranging from -5 to 60°C, time periods up to 160 hrs, and stress levels from 4 to 12 MN/m^ which represent stress-to-strength ratios of 0.3 to 0.7. The data obtained over these ranges of temperature, stress and resin content were successfully superposed on a single master curve of creep compliance versus time. On the basis of these results we propose a single expression, which describes the creep compliance (J) of the PC system as a product of separable func tions of temperature (T) , stress (a), resin content (v), and time (t) : J(T,a,v,t) - exp[A0] exp[-Aiaj exp[-&H/RT]tmA0 is itself dependent on resin content, ranging from 5,4 to 20.1 for the most highly filled PC and pure resin respectively; is constant (1.3 ± 0.1) for all systems. The activation energy (aH) is independent of temperature (Arrhenius behavior) and separable into two terms, one dependent on resin content (H0, ranging respectively from 18.6 to 11.1 for the pure resin and most highly filled PC) the other stress-dependent (Hwhere Hi = 0.83 ± 0.03 for all systems). These results indicate that the creep behavior of polyester PC is governed by its polymer matrix. The time depen dence (for periods up to 60 hours) can be represented by a power law model in which the exponent m (0.66 ± 0.05 for all polyester PC systems) is a material parameter.