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

The use of kaolinite as a pozzolanic activator in the hydration of cement is widely established. The optimum calcination conditions and the scientific basis of the reaction kinetics for the systems metakaolinite (MK)/lime, used as a standard system, and metakaolinite (MK)/cement have been set. These treatments reach their maximum effectiveness in the presence of non-altered calcite. The objective of this research is to determine the influence that calcite has on the pozzolanicity of the kaolinite, in order to do so, different mixtures kaolinite (K)/calcite (Ca) thermally activated at 600ºC and 750ºC for 2 hours were prepared. The products obtained in the pozzolanic reaction were studied with XRD and SEM/EDX analysis. The calcite addition generated an inhibitor effect in the reactivity of natural kaolinite (K) when the thermic activation is at 750°C for 2 hours. The optimal calcination conditions regardless of the proportion of calcite are 600°C/2 hours.

Scrap tyres are one of the most serious wastes that are landfilled with small percentages. Recycled scrap tyres are being used in different domains of industry because they are notdegradable. The experimental work focused on mechanical properties and durability indicators of self-compacting sand concretes blended with recycled rubber. Such modified concretes comprised 5, 10, 15 and 20% of rubber fine powder (RFP) and coarse particles (RCP) as partial substitutions of natural sand and aggregates. To shed light on physical and mechanical properties rubber particles effects, ordinary vibrated and self-compacting as well as self-compacting sand concretes (SCSCs) were characterised. Special attention was given to compression and bending performances of SCSCs. Identification of two durability indicators — water porosity and density — was assessed, according to AFGC specifications. Experimental findings enhanced previous literature reported statements and demonstrated that use of rubber particles as substitutes improved performances of elaborated SCSCs and produced eco-friendly materials that are appropriate for large surface applications such as pavements and terraces as well as civil engineering constructions.

Compared to normal concrete, packing density optimised Ultra High Performance Concretes have a high shrinkage up to 1 mm/m due to their high cement content. Especially in the first 24 hours approximately 80 % of the final shrinkage is reached which reduces the early strength due to microcracks. Instead of additives within the scope of this research work, parts of normal portland cement (NPC) were substituted by Calcium Sulfoaluminate (CSA) Cement and Calcium Aluminate (CA) Cement with the aim to reduce shrinkage of UHPC-mixture as well as a fast setting. CSA-cements with low CO2 footprint are characterised by their fast strength development and expansion behaviour due to early ettringite formation. X-ray diffraction was used to study the phase development. The influence on the shrinkage value was measured by shrinkage tests. In addition, the development of the microstructure was investigated by scanning electron microscopy. Finally, the influence on the strength development was correlated by ultrasonic measurement. These techniques allow a prediction of the setting process in the early stages. Finally, an environmentally friendly NPC-CSA blend could be developed which, in addition to high early strength, also achieves low shrinkage. Furthermore, the influence of the ettringite formation on the microstructure could be determined.

Converter steel slag exhibits very low hydration activity compared to ordinary portland cement. To increase its reactivity, a mixture with metakaolin (Al2O3·2SiO2) was designed to increase the binding capacity. Metakaolin was used for its purity and high pozzolanic reactivity, owing to its high alumina and silica content. Two systems were prepared, metakaolin and portlandite as a reference, and the second system was composed of converter slag and metakaolin. Reactivity was assessed by measuring the heat release of the hydration reactions by isothermal calorimetry. Calorimetry results show the cumulative heat of converter slag increases when metakaolin is added. Furthermore, new hydration products were identified. Large area phase mapping based on SEM/EDX spectral imaging was done to investigate the reactions between the components.