FLEXURAL CREEP BEHAVIOR OF POLYMER CONCRETE SYSTEMS

[摘要] The creep of polymer concrete (PC) systems based on unsaturated polyester/styrene and versamid-cured epoxy resins was investigated using PC systems with different resin and aggregate contents, as well as the unfilled resins respectively. In both polyester and epoxy PC systems data was obtained at different temperatures, stresses, and resin contents. Data reduction made it possible to describe the creep compliance (J) of PC systems as a product of separable functions of time (t), temperature (T), stress ($sigma$) and resin volume fraction (v): J(t,T,$sigma$,v) = J$sb{m r}$ (exp (-$Delta$H$sb{m T}$/RT) exp (K$sb{sigma}sigma$) exp (K$sb{m v}$v) t)$sp{m m}$. The activation energy of the creep compliance is independent of temperature (Arrhenius behavior), decreases with increasing stress, and increases with resin content, indicating that creep behavior of the aggregate-filled PC systems is governed by the polymer matrix. Use of this master curve enables prediction of the long-term creep compliance of different PC systems through a range of temperatures, stresses and resin contents from limited data on a single system over short time periods (ca. 10 hours). Introduction of chopped glass fiber in the polyester PC systems (in addition to aggregate and filler) enhanced their short-term flexural strength as well as their creep resistance. It also extended the stable creep domain to stress-to-strength ratios of 0.8. The creep data obtained with fiber-reinforced PC systems at different levels of the governing variables (temperature, stress, resin content) were also reduced to a master curve using the triple-superposition scheme. Treatment of the glass fibers with silane coupling agent and dispersion of the mineral montomorrilonite (MMT) into the resin produced further enhancement in both the short-term flexural strength as well as the long-term creep resistance of fiber-reinforced PC systems. Morphological studies of the fracture surface of the PC systems indicated either adhesive failure (disbonding of the aggregate or the fiber from the resin matrix) or cohesive failure (aggregate or fiber rupture). The mode of failure depends on the size of aggregate, type of binding polymer, treatment of glass fiber and use of special additives. (Abstract shortened with permission of author.)

[发布机构] Rice University