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 production of cement by calcination of limestone releases large amounts of carbon dioxide. Development of concrete quality lead to optimize the sustainability and maintenance phases of concrete structures, so, using supplementary cementitious materials (SCM) is one of the methods adapted to reduce the environmental impact of cement production. In addition, self-healing of concrete appears as a process to considerably improve the durability of a damaged structure [1]. As revealed by most analyses, mineral additions can be used to improve the autogenous healing ability of cementitious materials [2].

In this study, the influence of using a combination of SCMs, such as ground granulated blast furnace slag and metakaolin, on the mechanism of autogenous crack healing was assessed in ternary formula. Self-healing evolution was characterised by means of mechanical tests carried out on notched mortar samples with different substitution ratios. The mechanical recovery was investigated after the healing period. Moreover, the micro-chemical structure of the healing products was determined using various techniques (TGA, SEM/EDS and XRD). The primary results showed that using metakaolin and ground granulated blast furnace slag together greatly improve the healing efficiency.

MgO/hydromagnesite (Mg5(CO3)4(OH)2·4H2O, abbreviated as HY) blends are cementitious materials, which set and harden when mixed with water. These blends reach acceptable strengths and therefore can potentially be used as binders in mortars and concrete. In case MgO is derived from carbonation of magnesium silicates and subsequent calcination, MgO/HY blends offer the possibility to be used as alternative binders with reduced carbon footprint compared to normal portland cement-based products.

This study focuses on the characterization of hydration products and mechanical properties of MgO/HY blends. Hydration of solely MgO leads to formation of brucite (Mg(OH)2) without any strength-building properties. In contrast, by blending MgO with hydromagnesite, it is possible to produce mortar samples with a strength of up to 11.0 ± 0.4 MPa (1595 ± 58 psi) after 28 d. Moreover, blending with hydromagnesite accelerates early hydration of MgO. XRD and TGA studies of hydrated blends revealed the presence of brucite and of a poorly crystalline, unidentified hydrate phase. The latter might play an important role in strength development.

The feasibility of producing “just add water” alkali-activated self-consolidated (AASCC) mixtures using multi-powder activators and various cement-less binder combinations was evaluated in this study. During this study, fresh properties for mortar mixtures were evaluated by conducting the mini-slump flow test. Moreover, the relative performance of activated mortars and potential interactions among materials used in the mixtures was examined using the isothermal calorimeter. The performance of the hardened mortar mixtures was evaluated after 3, 7 and 28 days by conducting compressive strength tests. Results indicated an increase in the mechanical properties was observed while increasing the dry-powder activator ratio and source material nature for ground and non-ground mixtures.

It has been well stablished by several studies that LC3 requires an additional amount of gypsum on top of the normal dosage contained in OPC. In this manner, the second (aluminate) peak do not overlap with the first (alite) peak. This required increase of the sulfate content is attributed to the additional aluminate phases introduced to the system by the addition of calcined clay. However, a correlation between metakaolin (alumininosilicate phase) content and the amount of additional gypsum required for proper sulfation has not been found, and the relationship between these parameters and the position of the aluminate peak is not clear. This study explored in depth this issue in order to further understand the driving mechanism controlling the sulfate demand in LC3. Our results show that there is no direct link between the aluminate phase content and the gypsum demand. On the contrary, the driving mechanism is linked to the specific surface area that the mineral additions (calcined clay and limestone) introduce to the system, interaction commonly referred as filler effect.