Modifications to reaction mechanisms, phase assemblages and mechanical properties of alkali-activated slags induced by gypsum addition

IF 10.9 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement and Concrete Research Pub Date : 2023-09-06 DOI:10.1016/j.cemconres.2023.107311

Abdelrahman Hamdan, Haemin Song, Zuobang Yao, Mohammed Fouad Alnahhal, Taehwan Kim, Ailar Hajimohammadi

{"title":"Modifications to reaction mechanisms, phase assemblages and mechanical properties of alkali-activated slags induced by gypsum addition","authors":"Abdelrahman Hamdan, Haemin Song, Zuobang Yao, Mohammed Fouad Alnahhal, Taehwan Kim, Ailar Hajimohammadi","doi":"10.1016/j.cemconres.2023.107311","DOIUrl":null,"url":null,"abstract":"<div><p>Alkali-activated slags (AASs) are often reported to exhibit fast settings, undermining their utilisation as sustainable binders from a technological point of view. Although gypsum was shown in previous studies to change the setting time of AASs, understanding the mechanism behind the changes in the reactivity and microstructure of the AASs in the presence of gypsum remains unclear which limits its utilisation in AASs. For the activator conditions used in this research (i.e., Na<sub>2</sub>O/raw material = 4.5 % and SiO<sub>2</sub>/Na<sub>2</sub>O = 1.0), gypsum was observed to dissolve quickly in the system, promoting the precipitation of portlandite and thenardite phases which led to a reduction in the pH of the pore solution causing a slow dissolution of slags. Furthermore, gypsum addition increased the setting time and delayed the compressive strength development of the paste, accompanied by a reduction in the total measured heat. The description of the changes in phase assemblages and kinetic of the system provided here is fundamental for predicting the behaviour of gypsum in AASs and promoting the industrial wide-uptake of AAS technology.</p></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":"174 ","pages":"Article 107311"},"PeriodicalIF":10.9000,"publicationDate":"2023-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0008884623002259/pdfft?md5=6fce591f25d939f0b2bd18bd490e478a&pid=1-s2.0-S0008884623002259-main.pdf","citationCount":"1","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cement and Concrete Research","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0008884623002259","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: 1

Abstract

Alkali-activated slags (AASs) are often reported to exhibit fast settings, undermining their utilisation as sustainable binders from a technological point of view. Although gypsum was shown in previous studies to change the setting time of AASs, understanding the mechanism behind the changes in the reactivity and microstructure of the AASs in the presence of gypsum remains unclear which limits its utilisation in AASs. For the activator conditions used in this research (i.e., Na₂O/raw material = 4.5 % and SiO₂/Na₂O = 1.0), gypsum was observed to dissolve quickly in the system, promoting the precipitation of portlandite and thenardite phases which led to a reduction in the pH of the pore solution causing a slow dissolution of slags. Furthermore, gypsum addition increased the setting time and delayed the compressive strength development of the paste, accompanied by a reduction in the total measured heat. The description of the changes in phase assemblages and kinetic of the system provided here is fundamental for predicting the behaviour of gypsum in AASs and promoting the industrial wide-uptake of AAS technology.

查看原文本刊更多论文

石膏对碱活性渣反应机理、相组合及力学性能的影响

碱活性矿渣(AASs)经常被报道为快速凝固，从技术的角度来看，这破坏了它们作为可持续粘合剂的利用。虽然先前的研究表明石膏可以改变AASs的凝固时间，但对石膏存在下AASs反应性和微观结构变化背后的机制尚不清楚，这限制了其在AASs中的利用。在本研究中使用的活化剂条件下(即Na2O/原料= 4.5%，SiO2/Na2O = 1.0)，石膏在体系中溶解迅速，促进了波特兰相和thenardite相的沉淀，导致孔隙溶液pH值降低，导致炉渣溶解缓慢。此外，石膏的加入增加了膏体的凝结时间，延缓了膏体的抗压强度发展，并伴随着总测量热量的降低。这里提供的相组合和系统动力学变化的描述是预测石膏在AAS中的行为和促进AAS技术在工业上广泛采用的基础。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Cement and Concrete Research 工程技术-材料科学：综合

CiteScore

20.90

自引率

12.30%

发文量

318

审稿时长

53 days

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.