Long-Term Shear Creep Behavior of Polymer-Based Injection Mortar Systems

Abstract

To assess the lifetime of resin-based injection mortar systems, a fundamental knowledge of their long-term behavior is necessary. In this research, the long-term shear creep modulus of two commercially available polymer-based injection mortar systems was investigated. Besides an epoxy resin based injection mortar system (EP), a vinyl ester resin based injection mortar system (VE) was utilized. Therefore, an accelerated characterization method providing shear creep modulus data considering various material states was implemented. Due to the sensitivity of the injection mortar systems to curing state and moisture content, the shear creep master curve was generated by testing under stable material conditions. Hence, upper bound material conditions with a defined curing state (cured) and moisture content (dry) were introduced. For this reference state I, shear creep curves were determined at different temperatures. Based on the time-temperature shift methodology, for both injection mortar systems shear creep master curves were generated for up to 50 years. To allow for an evaluation of the influence of curing state and moisture content, reference state II and reference state III were defined as lower bound material conditions. Due to the long-term instability of these reference states, short-term tests were utilized to evaluate reduction factors enabling a shift of the shear creep master curve of reference state I. Together, these results provide an evident effect of curing state and moisture content. For both injection mortar systems, the effect of curing state was rather small and the influence of moisture content was more pronounced.