International Concrete Abstracts Portal

Sponsors: American Concrete Institute, RILEM, Université de Sherbrooke, CRIB, Université Toulouse III, Lmdc Toulouse, Kruger Biomaterials, Euclid Chemical, Prodexim International inc., BASF Master Builders, ACAA Editor: Arezki Tagnit-Hamou In July 1983, the Canada Centre for Mineral and Energy Technology (CANMET) of Natural Resources Canada, in association with the American Concrete Institute (ACI) and the U.S. Army Corps of Engineers, sponsored a five-day international conference at 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 taken place 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 renewed interest in alternative and sustainable binders and supplementary cementitious materials, a new series was launched by Sherbrooke University (UdeS); ACI; and the International Union of Laboratories and Experts in Construction materials, Systems, and Structures (RILEM). They, 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 in Montréal, QB, Canada, from October 2 to 4, 2017. The conference proceedings, containing 50 refereed 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 held online from June 7 to 10, 2021. The conference proceedings, containing 53 peer reviewed papers from more than 14 countries, were published as ACI SP-349. 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 was to highlight advances in the field of alternative and sustainable binders and supplementary cementitious materials, which are receiving increasing attention from the research community. To all those whose submissions could not be included in the conference proceedings, the Institute and the Conference Organizing Committee extend their appreciation for their interest and hard work. Thanks are extended to the members of the international scientific committee to review the papers. Without their dedicated effort, the proceedings could not have been published for distribution at the conference. The cooperation of the authors in accepting reviewers’ suggestions and revising their manuscripts accordingly is greatly appreciated. The assistance of Chantal Brien at the Université de Sherbrooke is gratefully acknowledged for the administrative work associated with the conference and for processing the manuscripts, both for the ACI proceedings and the supplementary volume. Arezki Tagnit Hamou, Editor Chairman, eleventh ACI/RILEM International Conference on Cementitious Materials and Alternative Binders for Sustainable Concrete (ICCM2021). Sherbrooke, Canada 2021

Ye’elimite-rich cements or calcium sulfoaluminate cements (CSA) are commercialized to prepare shrinkage compensation and self-stressing concretes. Moreover, CSA cements show environmentally friendly characteristics associated to their production, which include reduced CO₂ footprint. The expansive behavior of CSA cements is mainly controlled by ettringite amount, produced upon hydration of the key-phase, ye’elimite [Ca₄(Al₆O₁₂)SO₄]. This paper presents, on one hand, the optimal conditions for the synthesis of highly pure ye’elimite by solid state reactions, and on the other hand, it shows a fundamental description of ye’elimite formation mechanisms. Another aspect of the study encompasses the influence of fineness and citric acid addition on ye’elimite phase dissolution, then on hydrates composition of lab made ye’elimite-rich cement. For the fineness effect study, a highly fine and pure ye’elimite was originally synthetized by sol-gel methods. Various experimental techniques were performed to conduct the different aspects of the present study, namely XRD-Quantitative Rietveld analysis, Thermal analysis (TGA, DTA and Dilatometry), SEM (BSE imaging and EDS mapping), BET analysis, PSD by laser diffraction, and Image analysis (2D porosity and 2D PSD).

Sulfate attack is generally classified into chemical and physical sulfate attack. It is significantly different from lab ponding tests, instead, so called physical sulfate attack dominates in semi-immersed conditions which primarily occurred in field. However, due to its greater complexity, it has been strongly neglected and less investigated. This paper concerns developing a new test approach for physical sulfate attack degradation investigation and understanding the mechanisms behind it. The new test setup allowing unidirectional flow that enables to study it under controlled conditions (i.e., constant wicking action over fixed thickness with fixed relative humidity). To imitate the real field condition, sodium sulfate solution was used in contact with one side and refreshed every month, on the other side the relative humidity was controlled at 55 %. portland cement paste specimens were used with the proposed setup in the semi-immersed conditions to investigate the effect of w/c on sulfate attack. After several months of exposure to 30 g/L sulfate solution, the profile of sulfate ingression and phase assemblage was investigated by SEM-EDS and XRD, respectively. The lateral expansion and physical appearance of the samples were tracked over time. The results indicated physical and chemical sulfate attack occurred simultaneously on both sides of single sample and mechanisms and parameters involved were further discussed.

This study presents an accurate corrosion prediction through an intelligent approach based on deep learning. The deep learning is used to predict the time-to-corrosion induced cover cracking in reinforced concrete elements exposed to chlorides ions. The key parameters taken into consideration include thickness, quality and condition of the concrete cover. The prediction performance of the deep learning model is compared against traditional machine learning approaches using neural network and genetic algorithms. Results show that the proposed approach provides better prediction with higher generalization ability. The efficiency of the method is validated by an accelerated corrosion test conducted on 91 and 182-day moist cured reinforced fly ash concrete samples with different water-to-binder ratios. The results are in agreement with the model predictions. They also show that using the proposed model for numerical investigations is very promising, particularly in extracting the effect of fly ash on reducing the extent of corrosion. Such an intelligent prediction will serve as an important input in order to assist in service life prediction of corroding reinforced concrete structures as well as repair evaluation.

Strain-hardening geopolymer composite (SHGC) based on industrial wastes and by-products has emerged as a feasible alternative to strain-hardening cementitious composite (SHCC). Lately, a novel slag/fly ash-based SHGC with promising strain-hardening tensile performance and multiple cracking behavior has been successfully developed. However, its environmental impact with regards to its global warming potential and energy consumption remain to be evaluated.

This paper presents an evaluation and comparative study of the environmental impact factors of a newly developed slag/fly ash-based SHGC and three different types of conventional SHCC materials. The CO₂ equivalent global warming potential (GWP) and the embodied energy (EE) were calculated under a life cycle assessment scheme based on the product stage. SHGC has significant advantages in terms of the global warming potential (GWP) while maintaining comparable or lower embodied energy (EE) when compared with greener version of SHCC materials and typical SHCC material (ECC M45), respectively. It could be concluded that the newly developed slag/fly ash-based SHGC demonstrates a very promising LCA record while possessing excellent technical performance. Consequently, SHGC could serve as a promising alternative for SHCC materials with considerably lower environmental impact.