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Showing 1-5 of 586 Abstracts search results

Document: 

SP349

Date: 

April 28, 2021

Publication:

Symposium Papers

Volume:

349

Abstract:

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


Document: 

SP-349_25

Date: 

April 22, 2021

Author(s):

Klaus-Juergen Huenger and Mario Kositz

Publication:

Symposium Papers

Volume:

349

Abstract:

Supplementary cementing materials (SCM) have a great importance for preventing ASR in concrete structures worldwide. Different materials were used, e.g. fly ashes, silica fume or metakaolin. However, the results are often contradictory. What works with one aggregate does not necessarily work with another, or in other cases, the efficiency is not the same. Not all effects can be explained by fluctuations in the SCM composition.

Long-term investigations were carried out using three different aggregates. Concrete prisms were produced, and parallel aggregates were stored together with different SCM`s (different types and concentrations) in highly alkaline solutions with and without calcium hydroxide in the system. The reaction products, which precipitated as a result of the interactions between aggregate and SCM`s at different storage times, could be investigated by NMR and even XRD. The results were surprising because different aggregates formed different reaction products when using the same SCM. Such effects can only be explained by the release of different soluble minerals that are part of aggregates.

The conclusion is that obviously aggregates control the formation process of reaction products which are formed as a result of the interactions between SCM`s and aggregates. And these products are responsible for preventing ASR when using the SCM`s.


Document: 

SP-349_05

Date: 

April 22, 2021

Author(s):

Corentin Le Talludec, Annabelle Phelipot-Mardelé, and Christophe Lanos

Publication:

Symposium Papers

Volume:

349

Abstract:

Geopolymers are interesting solutions to avoid the use of traditional portland cement. Many studies focus on geopolymers formulation and final performances highlighting the short setting time and the rapid increase of mechanical performances. However, it is necessary to adapt the formulation regarding the components (including origin, reactivity, chemical formula). The successive steps to achieve the geopolymerization of an aluminosilicate in alkaline media are very sensitive to any change in the molar ratios of Si, Al and M (cation) available in the solution. This study focuses on Na-geopolymers. Several formulations performed using metakaolin, silica fume and soda are tested. Samples are subject to mass monitoring and shrinkage measurement varying the curing conditions. Long stabilization times (one month), and significant shrinkage, in the order of 10 %, are quoted. The interaction between autogenous shrinkage and drying shrinkage is discussed. The link between volume and mass variations suggests a large contribution of the drying shrinkage. This phenomenon interferes with the last steps of geopolymerization leading to the hardening. The results show that a part of the formulation water remains trapped in the binder matrix after the geopolymerization. TGA analysis confirm the results. To limit the shrinkage, mix formulation is modified introducing various type of calcium silicate fillers.


Document: 

SP-336_01

Date: 

December 11, 2019

Author(s):

James Lafikes, Rouzbeh Khajehdehi, Muzai Feng, Matthew O’Reilly, David Darwin

Publication:

Symposium Papers

Volume:

336

Abstract:

Supplementary cementitious materials (SCMs) in conjunction with pre-wetted fine lightweight aggregate to provide internal curing are being increasingly used to produce high performance, low-shrinking concrete to mitigate bridge deck cracking, providing more sustainable projects with a longer service life. Additionally, the SCMs aid in concrete sustainability by reducing the amount of cement needed in these projects. This study examines the density of cracks in bridge decks in Indiana and Utah that incorporated internal curing with various combinations of portland cement and SCMs, specifically, slag cement, Class C and Class F fly ash, and silica fume, in concrete mixtures with water-cementitious material ratios ranging from 0.39 to 0.44. When compared with crack densities in low-cracking high-performance concrete (LC-HPC) and control bridge decks in Kansas, concrete mixtures with a paste content higher than 27% exhibited more cracking, regardless of the use of internal curing or SCMs. Bridge decks with paste contents below 26% that incorporate internal curing and SCMs exhibited low cracking at early ages, although additional surveys will be needed before conclusions on long term behavior can be made.


Document: 

SP326-08

Date: 

August 10, 2018

Author(s):

Ojedokun Olalekan and P.S. Mangat

Publication:

Symposium Papers

Volume:

326

Abstract:

An Investigation on the mineralogical and chemical characterization, pore structure, chemical shrinkage and pozzolanic activity of commercially produced rice husk ashes (RHA 1 and 2) and a control silica fume (SF) are presented in this paper. RHA possesses high silica content like silica fume which is used as supplementary cementitious materials (SCM) in the production of concrete. There is a need for an alternative to silica fume in the production of concrete because of its high demand and relatively high cost.

The mineralogical composition of RHA 1 and 2 show high silica content of 77% and 84% respectively which is close to the silica content (˃80%) of class 2 silica fume. The oxides of Ca are 3.53% and 7.68% while Al is 1.19% and 1.29% for RHA 1 and 2 respectively which suggest that RHA is a low Ca+2 content binder. The results of chemical shrinkage of RHA 1, 2 and SF are 0.42 mL/g, 0.52 mL/g and 0.11 mL/g after 500 hrs of hydration. This indicates that RHA 2 has the highest reactivity (hydration) with water due to its highest Ca+2 content.


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