Two‐dimensional rigid body spring method based micro‐mesoscale study of mechanical strengthening/damaging effects to concrete by frost action

Abstract

Frost damage is an important issue for service life evaluation of concrete structures in cold regions. In fact, the frost action can have both strengthening and damaging effects on the mechanical properties of concrete material, depending on several environmental and material factors, and this complexity makes the damage evaluation more difficult in the real environment. This paper aims to develop a unified model through a micro‐mesoscale approach, which can quantitatively estimate and distinguish the strengthening/damaging effects by frost action. At microscale, the model takes into account the prestressed condition by internal pore pressures, as well as the change of effective elastic properties when ice forms in micropores. At mesoscale, the mechanical contribution of ice and liquid inside mesocracks is considered. Finally, the static mechanical behaviors of concrete under different situations are simulated based on a two‐dimensional discrete model rigid body spring method. The simulated results can clearly distinguish and separate each strengthening and damaging effect. The microice may enlarge the strengths by 50–110% while the mesocracks may reduce the strength by 40–80%, the effect of ice in mesocracks is also discussed. The final apparent performance depends on which strengthening/damaging effect is more dominant and is mainly controlled by the entrained air amount. Previous experiments are also used to verify the proposed model, and they are found in a good agreement.