In July of 1983, the Canada Centre for Mineral and Energy Technology of Natural Resources Canada (CANMET), in association with the American Concrete Institute (ACI) and the U.S. Army Corps of Engineers, sponsored a 5-day international conference in Montebello, Quebec, Canada, on the use of fly ash, silica fume, slag, and other mineral by-products in concrete. The conference brought together representatives from industry, academia, and government agencies to present the latest information on these materials and to explore new areas of needed research. Since then, eight other such conferences have been held around the world (Madrid, Trondheim, Istanbul, Milwaukee, Bangkok, Madras, Las Vegas, and Warsaw). The 2007 Warsaw Conference was the last in this series. In 2017, due to the renewed interest in alternative and sustainable binders and supplementary cementitious materials, a new series was launched by Sherbrooke University (Professor Arezki Tagnit-Hamou), American Concrete Institute (ACI), and the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM)—in association with a number of other organizations in Canada, the United States, and the Caribbean—sponsored the 10th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete (ICCM2017). The conference was held October 2-4, 2017, in Montréal, Canada. The conference proceedings, containing 50 reviewed papers from more than 33 countries, were published as ACI SP-320. In 2021, UdeS, ACI, and RILEM, in association with Université de Toulouse and a number of other organizations in Canada, the United States, and Europe, sponsored the 11th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete (ICCM2021). The conference was scheduled to take place in Toulouse, but due to COVID, it was held online June 7-10, 2021. The conference proceedings, containing 53 reviewed papers from more than 21 countries, were published as ACI SP-349. In 2024, the conference was finally held in-person in Toulouse from June 23 to 26, 2024, with the support of UdeS, ACI, and RILEM in association with Université de Toulouse (Martin Cyr) and a number of other organizations in Canada, the United States, and Europe. The purpose of this international conference was to present the latest scientific and technical information in the field of supplementary cementitious materials and novel binders for use in concrete. The new aspect of this conference is to highlight advances in the field of alternative and sustainable binders and supplementary cementitious materials for the transition to low carbon concrete. The conference proceedings, containing 78 reviewed papers from more than 25 countries, have been published as ACI SP-362. Thanks are extended to the members of the International Scientific Committee who reviewed the papers. The cooperation of the authors in accepting the reviewers’ suggestions and revising their manuscripts accordingly is greatly appreciated. The involvement of the steering committee and the organizing committee is gratefully acknowledged. Special thanks go to Chantal Brien (Université de Sherbrooke) for the administrative work associated with the conference and for processing the manuscripts for both the ACI proceedings and the supplementary volume. Arezki Tagnit Hamou, Editor Chairman, 12th ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete (ICCM2024). Sherbrooke, Canada, 2024

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.

Geopolymers are amorphous mineral materials manufactured from aluminosilicates and a strongly basic alkaline solution. One of their advantages is a lower carbon footprint than conventional cementitious binders. However, they are subject to significant drying shrinkage. In this study, geopolymer samples are produced from metakaolin, silica fume, and a potash solution. The mixture proportions are selected to reach the molar ration Si/Al=1.8, K/Al=1.15, and H₂O/K=5.3 leading to satisfactory rheology while mixing. Cylindrical samples (70 mm diameter, 40 mm height) are exposed to various curing conditions (temperature and relative humidity). A protocol including 3D scanning and instrumented macroindentation is used to monitor the drying shrinkage and hardening kinetics. Sample volume change and hardness are measured periodically until sample mass stabilization. It appears that the hardest samples are also the most cracked. Covering the sample for 5 days at 23°C or 24 hours at 40°C limits the shrinkage to ~1% but leads to a large decrease of the hardness compared to the hardest samples. An optimal geopolymerization requires a minimal amount of water which decreases with the progress of the reaction. Optimal curing conditions are identified. Thus, covering the sample for 3 days at 23°C allows to limit the shrinkage to 3% without cracking while reaching satisfactory mechanical properties.

There is no accepted test to determine the time needed for a cement paste microstructure to stabilize (and thus, for its diffusion coefficient to stabilize). This stabilization time is crucial when applying Crank's solution to Fick's law of diffusion of deleterious ions, as an important hypothesis is a constant diffusion coefficient. One potential approach involves utilizing the hyperbolic law to fit the evolution of bulk electrical resistivity, which is directly related to microstructural changes. This approach could provide a rapid means of determining the stabilization time and the final resistivity value. The objective of this work is to validate if this law is appliable for different types of cement and different types of curing and to determine the stabilization time for the different types of cement pastes: Ordinary Portland Cement (OPC) and blends with Supplementary Cementitious Materials (SCMs, i.e., slag, fly ash, silica fume, and limestone). Results show that the hyperbolic law for Portland cement allows predicting in 56 days the resistivity after 120 days with an error of less than 1%. Moreover, this law can be useful to estimate the time necessary for stabilization of the resistivity. However, it appears that this law is not applicable to every type of SCM especially silica fume and fly ash.

The increasing demand for sustainable building products with lower carbon footprints is a huge global challenge that can hardly be faced by conventional cementitious mixtures. In this context, the use of alternative primary binders, such as hydraulic lime, should be explored. Research in this direction should aim at the development of innovative eco-friendly materials with suitable mechanical performance. For the retrofitting of masonry structures, for instance, it may be necessary to improve their mechanical properties by incorporating supplementary cementitious materials (SCMs), further reducing, at the same time, their environmental impact.

This study investigates the effects of silica fume and metakaolin included either individually or together alongside natural hydraulic lime. The mechanical performance of such binary and ternary binders has been characterized in terms of flexural and compressive strength. Moreover, scanning electron microscopy (SEM) has been used to study the microstructure of the mixtures. Finally, a preliminary investigation concerning the effect of curing time in lime-based mixtures with combined silica fume and metakaolin has been performed to investigate the possible benefits of this approach. The results highlight the superior pozzolanic efficacy of silica fume compared to metakaolin and point towards the proper dosages of SCMs to achieve optimal mechanical performance.