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.

Modeling and Simulation on Static and Fatigue Behaviors of Intact and Frost Damaged Concrete with Ice-strengthening Effects

“…It could be found that the current model with integrating the ice-filled meso-cracks was closer to the experimental data. Besides, a previous study by Gong et al (2018) reported that the even under freezing temperature, the strength of frost damaged concrete could not go beyond the strength of intact concrete under room temperature, in case that only the ice-filled pores effect was integrated. However, current study indicated that the freezing strength of damaged concrete could be higher than the strength of intact concrete in thawing temperature by both simulation and experiment.…”

“…2.1 Meso-scale scheme with RBSM As introduced, the impacts of ice formation take place in different scales thus a multi-scale approach is needed. Following the scale separation by Gong et al (2018), the damaging and strengthening effects are explained.…”

“…For the ice-filled micro and meso pores, the bulk and shear modulus could be calculated according to the volume fraction of each component as suggested by Gong et al (2018), see Eq. (3).…”

“…1). Afterwards, the static behaviors of concrete with icing effect in pores was numerically proceeded by Gong et al (2017bGong et al ( , 2018 and validated by Lee et al (1988aLee et al ( , 1988b (second line in Fig. 1).…”

Experimental Examination of Electrical Characteristics for Portland Cement Mortar Frost Damage Evaluation

“…The de-icing agents can accelerate the frost damage of concrete; such damage has raised much concern in recent years [2]. Analytical studies have been conducted to predict the frost damage of concrete [3][4][5][6], but some discrepancies remain due to the complex of damage phenomena. In addition to salt scaling, which spoils the appearance of the concrete, more importantly, internal frost damage threatens safety.…”