Concrete

Saskatoon is facing widespread aggregate pop-outs in new concrete. The petrographic analysis revealed the root cause being freeze-thaw cycles and alkali silica reactions. Effective remedial techniques could reduce repair needs and enhance sidewalk aesthetics and safety.

This research established a method to quantify corrosion parameters like potential, current density, and Tafel slopes for rebar in simulated conditions. It examined how depassivation duration, chloride concentration, carbonation, and humidity affect these parameters. Notably, in partially saturated mortar, no distinct threshold was found for critical chloride content, and humidity significantly influenced depassivation indicated by shifts in corrosion parameters.

This dataset provides comprehensive corrosion parameter data for reinforcing steel (rebar) in simulated pore solutions and mortar. It includes detailed measurements of corrosion potential, corrosion current density, and Tafel slopes under various chloride levels and carbonation treatments. The data aims to shed light on the corrosion behaviour of rebar in environments that closely mimic real-world conditions.

This comprehensive corrosion model solves the evolution of the non-uniform microenvironment in cracked reinforced concrete and utilizes the environment-dependent homogenized corrosion kinetics to describe the electrochemical reaction on the rebar-concrete interface and solves for the potential and current fields. It explained the complex effects of cracks on corrosion, including corrosion reduction over time, crack size and healing effects.

This research develops a circuit model to simulate non-uniform rebar corrosion in concrete, revealing that concrete’s resistivity causes non-uniform rebar potential, affecting polarisation curves. This leads to overestimated Tafel constants and corrosion current density, particularly under higher concrete resistivity. Accurate corrosion predictions require potentiodynamic scans or averaging techniques like this model.

This study models rebar corrosion in an existing arch bridge, using historical environmental data to assess moisture, chloride concentration, and carbonation in concrete. Corrosion rates were deduced by correlating pore solution composition with electrochemical measurements of extracted rebar. Simulation results align well with actual conditions, showing significant corrosion on upper longitudinal rebars, especially near columns. Less exposed areas, like vertical columns and sheltered arch parts, exhibit minimal damage. The study concludes that carbonation, chloride ingress, and exposure to rain significantly accelerate corrosion rates.

Built in 1910, the Moose Jaw Inland Grain Terminal stands as a multi-cellular, concrete-constructed grain facility. Recent evaluations hinted at potential corrosion from concrete carbonation, prompting a proposal for extensive rehabilitation.

This study investigates the impact of cracks on water flow in concrete. It examines both artificial and natural cracks of varying widths (0.3 mm and 1.0 mm) under wetting and drying conditions. The Time Domain Reflectometry technique is used to monitor water content evolution around the cracks, revealing that all types of cracks behave similarly to open surfaces exposed to environmental elements.

The study focused on understanding the effects of cracking on transport characteristics under wetting and drying cycles. It involved examining the infiltration properties of natural and artificial cracks, monitoring saturation conditions, and employing numerical simulations to model saturation evolution. Results showed increased permeability and a complex water saturation pattern in cracked concrete, with significant findings on water flow simulation, material properties, and hysteresis in the Van Genuchten parameters. The study suggests different modeling approaches for accurately representing cracks in various scenarios.

This study investigates the role of chloride ion penetration in cracked structures. It addresses chloride ingress in both pre-cracked and cracked concrete, demonstrating the significant impact of cracks on chloride penetration, and models moisture and chloride movement under severe conditions.