{"title":"Investigation of alkali-silica reaction in alkali activated cements by thermodynamic modelling","authors":"Haoliang Jin, Sam Ghazizadeh, John L. Provis","doi":"10.1617/s11527-025-02781-z","DOIUrl":null,"url":null,"abstract":"<div><p>The likelihood and consequences of the alkali-silica reaction (ASR) in mortars and concretes based on alkali-activated materials (AAMs) are still under discussion, due largely to the characteristically high alkali levels of this class of cements. In this study, applying thermodynamic modelling to the study of ASR provides a new insight into ASR mechanisms as a function of binder chemistry. By considering different activators (NaOH, Na<sub>2</sub>SO<sub>4</sub>, Na<sub>2</sub>CO<sub>3</sub>, Na<sub>2</sub>O.<i>n</i>SiO<sub>2</sub> with various values of the modulus <i>n</i>) at different dosages, the volume of shlykovite-type ASR products that can potentially form in AAMs with partially reactive siliceous aggregates was calculated. The solution chemistry and phase assemblage after hydration provide further information to aid in explaining the observed trends. Although high concentrations of Na-bearing activators were used in the AAM formulations, much less Na-shlykovite and no K-shlykovite are formed, compared to Portland cement. The volume of Na-shlykovite formed decreases with an increase in the dosage of activators (for all activators tested), and with a decrease in the modulus of sodium silicate when this is the activator used. A high concentration of Ca after hydration, rather than the concentration of alkalis in the pore solution, is the controlling factor in shlykovite formation, which represents ASR in these simulations.</p></div>","PeriodicalId":691,"journal":{"name":"Materials and Structures","volume":"58 8","pages":""},"PeriodicalIF":3.9000,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1617/s11527-025-02781-z.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Materials and Structures","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1617/s11527-025-02781-z","RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The likelihood and consequences of the alkali-silica reaction (ASR) in mortars and concretes based on alkali-activated materials (AAMs) are still under discussion, due largely to the characteristically high alkali levels of this class of cements. In this study, applying thermodynamic modelling to the study of ASR provides a new insight into ASR mechanisms as a function of binder chemistry. By considering different activators (NaOH, Na2SO4, Na2CO3, Na2O.nSiO2 with various values of the modulus n) at different dosages, the volume of shlykovite-type ASR products that can potentially form in AAMs with partially reactive siliceous aggregates was calculated. The solution chemistry and phase assemblage after hydration provide further information to aid in explaining the observed trends. Although high concentrations of Na-bearing activators were used in the AAM formulations, much less Na-shlykovite and no K-shlykovite are formed, compared to Portland cement. The volume of Na-shlykovite formed decreases with an increase in the dosage of activators (for all activators tested), and with a decrease in the modulus of sodium silicate when this is the activator used. A high concentration of Ca after hydration, rather than the concentration of alkalis in the pore solution, is the controlling factor in shlykovite formation, which represents ASR in these simulations.
期刊介绍:
Materials and Structures, the flagship publication of the International Union of Laboratories and Experts in Construction Materials, Systems and Structures (RILEM), provides a unique international and interdisciplinary forum for new research findings on the performance of construction materials. A leader in cutting-edge research, the journal is dedicated to the publication of high quality papers examining the fundamental properties of building materials, their characterization and processing techniques, modeling, standardization of test methods, and the application of research results in building and civil engineering. Materials and Structures also publishes comprehensive reports prepared by the RILEM’s technical committees.