{"title":"Impact of alkalis and shrinkage-reducing admixtures on hydration and pore structure of hardened cement pastes","authors":"Hafsa Rahoui , Ippei Maruyama , Matthieu Vandamme , Jean-Michel Pereira , Martin Mosquet","doi":"10.1016/j.cemconres.2024.107620","DOIUrl":null,"url":null,"abstract":"<div><p>The hydration and pore structure of hardened cement pastes containing various amounts of alkali and hexylene glycol -a shrinkage-reducing admixture (SRA)- are studied. Until three months, SRA retards cement paste hydration regardless of alkali content; after seven days at most, this retardation diminishes with time. Alkalis increase the hydration degree at early ages for all pastes. The pore structure coarsens with the SRA: both the specific surface area and the volume of pores with a 5 nm entry size decrease in the presence of the SRA. The magnitude by which the SRA impacts the pore structure reduces with alkali.</p><p>In alkali media, the C-S-H gel uptakes alkalis and aluminum; modifying the C-S-H structure, the gel pore volume, and the interlayer space. The SRA depletes the alkalis from the solution and may increase the C-S-H alkali uptake, which could lead to changes in the gel pore volume and specific surface area.</p></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"184 ","pages":"Article 107620"},"PeriodicalIF":10.9000,"publicationDate":"2024-07-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cement and Concrete Research","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0008884624002011","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
The hydration and pore structure of hardened cement pastes containing various amounts of alkali and hexylene glycol -a shrinkage-reducing admixture (SRA)- are studied. Until three months, SRA retards cement paste hydration regardless of alkali content; after seven days at most, this retardation diminishes with time. Alkalis increase the hydration degree at early ages for all pastes. The pore structure coarsens with the SRA: both the specific surface area and the volume of pores with a 5 nm entry size decrease in the presence of the SRA. The magnitude by which the SRA impacts the pore structure reduces with alkali.
In alkali media, the C-S-H gel uptakes alkalis and aluminum; modifying the C-S-H structure, the gel pore volume, and the interlayer space. The SRA depletes the alkalis from the solution and may increase the C-S-H alkali uptake, which could lead to changes in the gel pore volume and specific surface area.
期刊介绍：
Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.
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