Effects of varying grades/pretreatments of recycled aggregates on the development of pore structures and ITZs within reactive magnesia cement (RMC) concrete

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

Cement and Concrete Research Pub Date : 2025-01-17 DOI:10.1016/j.cemconres.2025.107782

Yufeng Song, Jiaze Wang, Yinjie Huang, Jiawen Wang, Yitian Weng, Rui Ma, Kevin Seng Hong Pang, Shaoqin Ruan

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引用次数: 0

Abstract

This study explores the influence of incorporating recycled aggregate (RA) and CO2-pretreated recycled aggregate (CRA) in reactive magnesia concrete (RMC) formulations. Through comprehensive microscopic characterizations, the phase composition, carbonation degree, pore structure, and interfacial transition zone (ITZ) characteristics are examined in both interior and exterior regions of specimens. The findings highlight that RA and CRA contribute to a 28 d strength in RMC formulations 14% and 25% higher than that with NA, respectively. This enhancement is attributed to internal curing and significantly increased channels for CO2 diffusion within (C)RA specimens, leading to improvements in the modulus, hardness, and microstructures of the interior region—the traditionally weaker part in RMC-based concrete. Furthermore, a robust linear correlation is observed between ITZ characteristics, porosity, and compressive strength of CO2-cured specimens. Finally, utilizing different grades of RA improves the performance of RMC-based concrete to varying degrees while reducing costs, thus potentially expanding the application of RA in practical RMC-based concrete scenarios, regardless of RA quality.

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不同等级/预处理再生骨料对活性镁水泥（RMC）混凝土孔隙结构和ITZs发展的影响

本研究探讨了在活性镁混凝土（RMC）配方中掺入再生骨料（RA）和二氧化碳预处理再生骨料（CRA）的影响。通过全面的微观表征，研究了样品内部和外部的相组成、碳酸化程度、孔隙结构和界面过渡区（ITZ）特征。结果表明，RA和CRA对RMC配方28 d强度的贡献分别比NA高14%和25%。这种增强归因于内部养护和(C)RA试件内CO2扩散通道的显著增加，从而导致内部区域（传统上rmc基混凝土中较弱的部分）的模量、硬度和微观结构的改善。此外，还观察到co2固化试样的ITZ特性、孔隙率和抗压强度之间存在强大的线性相关性。最后，使用不同等级的RA在不同程度上提高了rmc基混凝土的性能，同时降低了成本，从而有可能扩大RA在实际rmc基混凝土场景中的应用，而不考虑RA的质量。

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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.