Nonlinear Gel Migration in Cracked Concrete and Broken Symmetry of Corrosion Profiles

Abstract

The initiation and subsequent propagation of corrosion-induced cracks is simulated by multi-phase mechanics where the coupled corrosion gel migration and crack-based fracture can be coherently taken into consideration. A key focus is given to the nature of corrosion products and their dependency on the corrosion rate and the anisotropic stiffness and permeability caused by cracking. Migration of corrosion gel to both micro-pores of cementitious composites and crack gaps are explicitly considered under the gradient of gel pressure, which is newly defined on the corrosion gel phase. The effects of cover depth, corrosion rate and the mix-proportion of concrete on the crack initiation and propagation are discussed with experimental facts. The broken symmetry of corrosion profile around reinforcing bars is successfully simulated as a nature even though the geometry of analysis domains would be in perfect symmetry. This scheme which allows kinematics of produced gel is indispensable for a versatile framework of durability mechanics.

Time-Dependent Capacity of Large Scale Deep Beams under Sus-tained Loads

“…Reproducibility of experimentally obtained shear-capacity was found to be about 5% around the mean values based upon the statistical survey of about 2,000 experimental specimens (Okamura and Higai 1980). As stated on the CPU parallel process-induced perturbation, variation in computed capacity can be also reproduced as the nature does Gebreyouhannes and Maekawa 2016) owing to the broken symmetry of failure mode.…”

Strong Coupling of Freeze-Thaw Cycles and Alkali Silica Reaction - Multi-scale Poro-mechanical Approach to Concrete Damages -

“…There are some slight differences in the ASR expansion between closed and open conditions. This is natural and mainly due to the randomness on multi-directional crack opening under rather uniform field of stresses before cracking and the broken symmetry is simply reproduced by using parallel computing process (Gebreyouhannes and Maekawa 2016). After ASR exposure, the FTC expansion has the similar tendency to the sole FTC event, but the amplitude become smaller.…”

“…28, the stiffness and ductility are the same but the strong coupling of these events has a greater compressive strength. In view of the nonlinear stability, so called broken symmetry cannot be avoided when ASR gel induced cracks are first introduced like the case of corrosion around reinforcing bars (Gebreyouhannes and Maekawa 2016). The following FTC brings about ice formation accompanying the further volumetric expansion.…”

“…The total liquid and solid pore pressure in pores and crack system can be calculated as an extension of previous models (Biot 1941(Biot , 1963Maekawa et al 2008;Gebreyouhannes and Maekawa 2016) as follows.…”

“…The system should start from the hydration stage in nano-scale, and then be upgraded to the physical and chemical equilibrium in porous media, and finally lead to the structural performance (Maekawa et al 2003(Maekawa et al , 2013. Based on this platform, dual impacts have been well modelled and simulated based on poro-mechanics, such as the fatigue effect of condensed water under traffic loads (Maekawa and Fujiyama 2013), the steel corrosion and crack opening caused by corrosion gels (Gebreyouhannes and Maekawa 2016), as well as the ASR expansion and damage (Takahashi et al 2016).…”