Enhancement in stability of air bubbles in mortar at fresh state with different SCMs

IF 3.4 3区工程技术 Q2 CONSTRUCTION & BUILDING TECHNOLOGY

Materials and Structures Pub Date : 2025-01-09 DOI:10.1617/s11527-024-02566-w

Qian Jiang, Cheng Yu, Qian Zhang

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引用次数: 0

Abstract

The stability of air bubbles is a critical factor in determining the performance of concrete. This study investigated the influence of various supplementary cementing materials (SCMs), with a 20% replacement of cement by weight, on the stability of foam in solutions and air bubbles in fresh mortars. Air bubble size distributions were measured using an air void analyzer and X-ray computed tomography at two intervals: from 5 to 60 min and from 60 to 180 min after the mixture was prepared. The results demonstrated that the number of small bubbles decreased while the number of large bubbles increased over time, with the most significant changes occurring within the initial 60 min. The results of the wettability tests were combined with those from the X-ray diffraction (XRD) analysis to identify a correlation between the stability of air bubbles and the wetting angle of the SCMs. It was observed that the contact angle of the SCMs approached 90° in cases where the air bubbles exhibited increased stability. The XRD patterns revealed significant differences in the mineral compositions between the bubble shells and the screened pastes from fresh mortar. The presence of a higher concentration of SCMs and hydration products on the bubble shells, compared to the paste, was identified as a potential reason for the observed differences in bubble stability. The utilization of specific SCMs has the potential to enhance bubble stability, in addition to the use of chemical admixtures.

Abstract Image

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不同SCMs对砂浆新鲜状态下气泡稳定性的增强作用

气泡的稳定性是决定混凝土性能的关键因素。本研究研究了各种补充胶凝材料（SCMs）对溶液中泡沫和新鲜砂浆中气泡稳定性的影响，以20%的重量替代水泥。在配制混合物后的5 - 60分钟和60 - 180分钟两个时间间隔内，使用气隙分析仪和x射线计算机断层扫描测量气泡大小分布。结果表明，随着时间的推移，小气泡的数量减少，而大气泡的数量增加，变化最显著的是在最初的60 min内。将润湿性测试结果与x射线衍射（XRD）分析结果结合起来，确定了气泡的稳定性与SCMs的润湿角度之间的相关性。观察到，在气泡稳定性增加的情况下，SCMs的接触角接近90°。XRD谱图显示，气泡壳与筛选后的鲜砂浆膏体在矿物组成上存在显著差异。与膏体相比，气泡壳上存在更高浓度的SCMs和水化产物，这被认为是观察到的气泡稳定性差异的潜在原因。除了使用化学外加剂外，使用特定的SCMs有可能提高气泡的稳定性。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Materials and Structures 工程技术-材料科学：综合

CiteScore

6.40

自引率

7.90%

发文量

222

审稿时长

5.9 months

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.