Simulating acoustic nonlinearity change in accelerated mortar bar tests: A discrete meso-scale approach

Alkali silica reaction (ASR) in concrete is a complex, multi-scale chemo-mechanical problem characterized by expansion and cracking of concrete meso-structure resulting in mechanical properties degradation. Currently available standardized tests to investigate concrete vulnerability to ASR (accelerated mortar bar test and concrete prism test) can give some insight for new structures, however, the assessment of residual load carrying capacity of existing ASR affected structures mostly rely on destructive evaluations. Promising alternatives are ultrasonic nondestructive evaluation techniques, but, they don’t provide a direct measurement of the damage characteristics and mechanical properties deterioration. This paper integrates nondestructive measurements with accurate computational modeling of ASR induced damage using the Lattice Discrete Particle Model (LDPM), a mesoscale model for concrete with superior modeling capability of fracturing behavior that was recently extended to account for ASR damage. The numerical simulations demonstrate the ability to replicate ultrasonic nonlinear phenomena and show its strong correlation with cracking evolution.