Fracture simulation of concrete with ASR and DEF expansions by RBSM

Abstract

In this study, cracking behaviors affected by two main expansion causes: Alkali-silica reaction (ASR) and Delayed ettringite formation (DEF), are predicted by the three-dimensional Rigid Body Spring Model (RBSM). By dissection concrete into 2~3mm randomized polynomial elements and analysis the forces between elements through spring connecting them, RBSM is especially a good solution for fracture analyses. For DEF, initial expansion strain is applied between mortar elements, to reflect the expansion caused by high temperature during curing, which is more concentrated in the inner part where mortar elements experienced higher curing temperature. While in the case of ASR, the expansion strain is applied at the mortar-aggregate interfaces, to reflect the alkali-silica gel formation in and around the aggregates. This is an effective approach to discuss the effect of these two common causes of concrete expansion in long-term, which is difficult to be analyzed using traditional experiment due to its long experiment term required and complexity of quantitatively determinate the contribution of each expansion cause. In this simulation, cracking patterns due to ASR and DEF are well presented. Especially in ASR case, cracks are more localized with expansion given more concentrated. In DEF case, localized crack is well simulated when the expansion is intensified in the center considering the hightemperature zone during the curing.