International Concrete Abstracts Portal

Professor Carolyn Hansson’s remarkable journey began in England, during the turbulence of the Second World War. Despite the hardships of wartime and the limitations imposed by rationing, Carolyn was raised in a nurturing environment by parents who instilled in her a deep respect for learning and perseverance. These values would guide her through an exceptional academic and professional life. As the sole woman at the Royal School of Mines, Carolyn studied metallurgy at Imperial College, where she later earned her PhD, focusing on superconductivity and crystal structures at liquid helium temperatures. Her postdoctoral path led her from industrial research at Martin Marietta Laboratories to academic positions at Columbia University and the State University of New York at Stony Brook, and later to Bell Laboratories in 1976. Her pivotal shift into corrosion science began in 1980 at the Danish Corrosion Centre, where she worked on a new type of cement and corrosion of steel in concrete. From Denmark to Canada, Professor Hansson continued her research at Queen’s University and later at the University of Waterloo, building an enduring legacy in the field of steel corrosion in concrete structures. Over the decades, Carolyn’s contributions to corrosion research have shaped and guided generations of engineers and scientists. Her pioneering studies—on electrical resistivity of concrete, quantifying reinforcement corrosion rates, and understanding the complex role of chlorides—remain foundational in the field. Her investigations into corrosion inhibitors, electrochemical chloride extraction, effects of concrete cracking on reinforcement corrosion, and corrosion-resistant steels continue to influence global practices in infrastructure resilience. This Special Publication celebrates more than 60 years of Professor Hansson’s contributions as a scientist, educator, and mentor. The papers collected here, presented at the 2025 Spring Convention in Toronto, reflect not only the lasting relevance of her work but also its future promise. Her vision stands as both a mirror to the past and a beacon for innovations yet to come in corrosion-resistant construction. O. Burkan Isgor David Tepke Ceki Halmen Neal Berke

Corrosion of reinforcement is a common deterioration problem for reinforced concrete structures at coastal areas causing early failure, increased maintenance costs, and significant safety problems. This paper combines a wellestablished diffusion-based service life estimation method with recently developed data-driven models on surface chloride concentration accumulation and critical chloride threshold distribution data to probabilistically analyze the effect of design parameters such as water-cement ratio (w/c), cover depth, and admixed chloride content in various coastal exposure zones. Results indicate that the used probabilistic analysis can result in changes to estimated service life values by an order of magnitude. Although w/c and cover depth were the most significant factors affecting the service life, parameters such as wind speed, temperature, exposure zone, and distance from the coast were identified as influencing the service life of coastal structures.

The management of municipal solid waste incineration fly ash (MSWI FA) has become a critical issue as its generation increases rapidly along with the global population growth. In this study, MSWI FA was treated via water-washing, and then the untreated and water-treated MSWI FAs (RFA and WFA) were blended with mainstream supplementary cementitious materials (SCMs), including ground granulated blast-furnace slag (GS), silica fume (SF), and limestone powder (LS). The MSWI FASCMblends were used as a cement replacement in a mortar. The content of MSWI FAs was set at 10% (by weight of binder) for all mortar mixtures. The content of GS and LS was also set at 10%, while the SF content was 2.5%. Flowability, setting time, isothermal calorimetry, compressive strength, and free-drying shrinkage tests were performed. The results showed that mortars containing raw (untreated) fly ash (RFA) had reduced strength, whereas mortars containing water-treated fly ash (WFA) displayed comparable or even higher strength than the control mortar (made with 100% cement) after 28 days. While mortars containing RFA showed increased drying shrinkage, mortars containing WFA exhibited diminutive or no increase in drying shrinkage when compared to the control mortar. Based on the test results, the mixture with a cement:WFA:GS ratio of 80:10:10 was the optimal binder for concrete applications.

Using particle packing models (PPMs) in combination with limestone fillers has been shown to be effective in proportioning eco-efficient concrete mixtures with reduced Portland cement content, resulting in suitable performance in fresh and short-term hardened states. However, the decrease in Portland cement and increase in limestone fillers may lower the pH of concrete, raising concerns about durability and long-term performance, potentially leading to increased corrosion of steel reinforcement in the presence of carbonation or chlorides. In this study, the performance of three eco-efficient concrete mixtures with varying cement (250, 200, and 150 kg/m³) and inert filler contents is evaluated against accelerated chloride exposure. The findings highlight the influence of the mixture proportioning and water-to-cement ratio on the resistance to chloride ingress. Ultimately, it is verified that the distance between cement particles is a major contribution towards chloride ingress.

Although limestone calcined clay cement (LC³) is a valid alternative to reduce the carbon footprint of cement production, some of its properties, like workability, still need to be investigated and fully understood. In this work, different cement pastes containing variable amounts of calcined clay with and without superplasticizer were analyzed. Measurements at the rheometer scale were performed to evaluate the superplasticizer’s effect on the samples’ workability. The amount of free water available after 1 hour of hydration in cement pastes was detected by Differential Scanning Calorimetry (DSC). Moreover, the Time-Domain Nuclear Magnetic Resonance (TD-NMR) was used to identify whether this water was contained either in capillary pores or in interhydrate spaces. The results obtained by DSC and TD-NMR revealed that pastes containing superplasticizers show a slightly higher amount of available free water, with a direct positive consequence on rheological properties. However, the amount of calcined clay (CC) in cement impacts both aspects: superplasticizer dosage to reach the target fluidity of pastes and workability retention over 60 minutes. Moreover, the confirmation of the exponential correlation between yield stress and the solid content of cementitious particles is possible when considering the detected capillary water as an indicator of the normalized concentration of solid particles.