Mechanisms of Alkali-Silica Reaction Mitigation in AMBT Conditions: Comparative Study of Traditional Supplementary Cementitious Materials

2022 ◽  
Vol 34 (3) ◽  
Author(s):  
Marie Joshua Tapas ◽  
Paul Thomas ◽  
Kirk Vessalas ◽  
Vute Sirivivatnanon
Keyword(s):  
Comparative Study ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Alkali Silica Reaction

scholarly journals Role of Aluminum and Lithium in Mitigating Alkali-Silica Reaction—A Review

2022 ◽  
Vol 8 ◽  
Author(s):  
Zhenguo Shi ◽  
Barbara Lothenbach
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Lithium Salts ◽  
Alkali Silica Reaction ◽  
Reaction Products ◽  
Ambient Conditions ◽  
Slow Kinetics ◽  
Zeolite Formation ◽  
Available Information

Effective mitigation of alkali-silica reaction (ASR) is critical for producing durable concrete. The use of alumina-rich supplementary cementitious materials (SCMs) and chemical admixtures such as lithium salts to prevent expansion caused by ASR was first reported 70 years ago, shortly after the discovery of ASR in 1940s. Despite numerous investigations, the understanding of the mechanisms of Al and Li for mitigating ASR remain partially inexplicit in the case of Al, and hardly understood in the case of Li. This paper reviews the available information on the effect of Al and Li on ASR expansion, the influencing factors, possible mechanisms and limitations. The role of Al in mitigating ASR is likely related to the reduction of dissolution rate of reactive silica. Moreover, the presence of Al may alter the structure of crystalline ASR products to zeolite or its precursor, but such effect seems to be not that significant at ambient conditions due to the slow kinetics of zeolite formation. Several mechanisms for the lithium salts in mitigating ASR have been proposed, but most of them are not conclusive primarily due to the lack of knowledge about the formed reaction products. Combination of Al-rich SCMs and lithium salts may be used as an economic solution for ASR mitigation, although systematic studies are necessary prior to the applications.

scholarly journals Microstructural Analysis of Concrete Using Cow Bone Ash for Alkali-Silica Reaction (ASR) Suppression

2020 ◽  
Vol 4 (2) ◽  
pp. 34-40
Author(s):  
Adanikin Ariyo ◽  
Funsho Falade ◽  
Adewale Olutaiwo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Microstructural Analysis ◽  
Cementitious Materials ◽  
Sem Analysis ◽  
Supplementary Cementitious Materials ◽  
Alkali Silica Reaction ◽  
Bone Ash ◽  
Cow Bone ◽  
Scanning Electron

Concrete pavements are prone to microstructural changes and deterioration when exposed to Alkali-Silica Reaction (ASR). ASR results in strength reduction, cracking, spalling and other defects in the concrete if left unchecked. Supplementary Cementitious Materials (SCMs) such as Cow Bone Ash (CBA) however can be used to improve concrete performance, hence its use in this study. Concrete samples were prepared at replacement levels of 0%, 5%, 10%, 15%, 20% and 30% of cement with Cow Bone Ash. The concrete samples were then subjected to petrographic and Scanning Electron Microscopy (SEM) analysis. Petrographic examination shows that the minimal and least amount of ASR gels and micro cracking were observed at 15% CBA replacement of cement in the concrete samples. Scanning Electron Microscopy (SEM) analysis shows that changes in the elemental composition of the concrete samples is related to the effect of CBA which enhances adhesion in the concrete. SEM analysis show that, in general, the change in microstructure in the concrete was mainly due to the change in the arrangement of the C-H-S compounds. The microstructure analysis indicates that CBA in concrete influences the densification of the concrete at the transition zone, resulting in a much lower porosity. This results in the concrete having a tightly bound layer that repels ingress of water and thereby inhibiting cracks and gel formation as water is a contributing factor to the ASR in concrete.

scholarly journals Properties of Western Cape Concretes with Metakaolin

2018 ◽  
Vol 199 ◽  
pp. 11011
Author(s):  
Alice T. Bakera ◽  
Mark G. Alexander
Keyword(s):  
Dilution Effect ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Superior Performance ◽  
Alkali Silica Reaction ◽  
Western Cape ◽  
Western Cape Province ◽  
Calcined Clay ◽  
Global Demand ◽  
Strength And Durability

A global demand for affordable, sustainable, and durable concrete has resulted in growing use of Supplementary Cementitious Materials (SCMs). In the Western Cape Province of South Africa, the readily available SCM is Granulated Ground Corex Slag (GGCS), although fly ash can also be obtained. However, the availability of these SCMs, particularly GGCS, is subject to market and other extraneous factors, and this may render them vulnerable as sources of SCM for concrete. This points to the need for innovation and investigating other potential SCMs which are economically and environmentally effective. Metakaolin, a high-grade type of calcined clay, emerges as a possible potential future SCM in the Western Cape. This study aimed at investigating the influence of a locally available metakaolin on mechanical (compressive and tensile strength), and durability (concrete penetrability and potential to mitigate Alkali Silica Reaction (ASR)) properties of Western Cape concrete. In comparison to GGCS, concretes with metakaolin showed superior performance in both mechanical and durability properties. This was attributed to its role in concrete in terms of accelerating hydration reactions, pozzolanic activity, and dilution effect. Metakaolin can therefore be regarded as a beneficial substitute for GGCS in Western Cape concrete. However, questions that remain include cost-effectiveness, and the awareness and willingness of industry to incorporate this material.

A Comparative Study on the Influence of Supplementary Cementitious Materials on Marine Concrete

2019 ◽  
Vol 48 (3) ◽  
pp. 20190138
Author(s):  
Xiaosheng Li ◽  
Zhonghe Shui ◽  
Yun Huang ◽  
Xu Gao ◽  
Jie Chen
Keyword(s):  
Comparative Study ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Marine Concrete

Mitigation of Alkali–Silica Reaction by Hydrated Alumina

2017 ◽  
Vol 2629 (1) ◽  
pp. 15-23 ◽  
Author(s):  
Tiffany Szeles ◽  
Jared Wright ◽  
Farshad Rajabipour ◽  
Shelley Stoffels
Keyword(s):  
Fly Ash ◽  
Ion Transport ◽  
Pore Size ◽  
Pore Solution ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Alkali Silica Reaction ◽  
Hydrated Alumina ◽  
Recent Trends ◽  
Water And Ion Transport

Recent trends and forecasts on the availability of fly ash, slag, and lithium admixtures for use in concrete suggest a need to seek reliable alternatives for the mitigation of alkali–silica reaction (ASR). One such option may be aluminum-based admixtures. Past studies have shown that supplementary cementitious materials that contain alumina (Al2O3) are more effective at mitigating ASR than are supplementary cementitious materials purely rich in silica (SiO2). To establish the effectiveness and mechanisms of ASR mitigation by alumina, this research used pure hydrated alumina, Al(OH)3, as a cement replacement. The objectives of the study were to determine if Al(OH)3 can successfully mitigate ASR and to investigate five hypothesized mechanisms by which Al(OH)3 may mitigate ASR. The hypothesized mechanisms are ( a) reducing pH and alkalis in concrete pore solution, ( b) consuming and reducing portlandite and dissolved calcium in the pore solution, ( c) reducing silica dissolution and damage to aggregates at high pH, ( d) altering the composition of ASR gel and creating innocuous gels, and ( e) reducing water and ion transport by reducing the porosity and pore size of cement paste. The results show that Al(OH)3 can effectively mitigate ASR through mechanisms ( a), ( b), and primarily ( c).

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