Mitigating water curing strength degradation, enhancing water resistance, and improving the properties of metakaolin geopolymer cement with CaO

IF 6.2 2区工程技术 Q1 ENGINEERING, MULTIDISCIPLINARY

Ain Shams Engineering Journal Pub Date : 2026-01-01 Epub Date: 2025-11-18 DOI:10.1016/j.asej.2025.103869

Alaa M. Rashad , E.A. Fahmy , Omnia Farouk Hussien , Reham Abu-Elwafa Mohamed

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Abstract

Metakaolin (MK) geopolymers offer excellent sustainability and high compressive strength but exhibit water sensitivity, high shrinkage, and reduced durability due to their calcium-free nature. This study investigates the incorporation of calcium oxide (CaO) at 2.5–15% (in 2.5% increments) to overcome these shortcomings. Samples were cured under both air and water conditions to evaluate changes in workability, setting time, strength development, and microstructural evolution. Increasing CaO content reduced flowability and accelerated setting but significantly improved compressive strength, dimensional stability, and durability. Optimal performance was achieved at 10% CaO, forming a hybrid binder composed of coexisting N-A-S-H and C-(A)-S-H gels that produced a denser, more cohesive microstructure with reduced permeability and drying shrinkage. The results confirm that CaO incorporation is an effective strategy to enhance MK geopolymer cement performance and long-term stability. Overall, these findings highlight the potential of CaO modification to develop more durable, sustainable, and practical metakaolin-based construction materials.

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掺CaO的偏高岭土聚合物水泥可减轻水固化强度退化，提高抗水性，改善其性能

偏高岭土（MK）地聚合物具有优异的可持续性和高抗压强度，但由于其无钙性质，表现出水敏感性、高收缩率和耐久性降低。本研究以2.5% - 15%（以2.5%的增量）加入氧化钙（CaO）来克服这些缺点。样品在空气和水两种条件下固化，以评估和易性、凝固时间、强度发展和微观结构演变的变化。增加CaO含量会降低流动性和加速凝固，但会显著提高抗压强度、尺寸稳定性和耐久性。当CaO含量为10%时，性能最佳，形成了由共存的N-A-S-H和C-(a)- s - h凝胶组成的混合粘合剂，产生了更致密、更有凝聚力的微观结构，降低了渗透性和干燥收缩率。结果表明，CaO的掺入是提高MK地聚合物水泥性能和长期稳定性的有效策略。总的来说，这些发现突出了CaO改性在开发更耐用、可持续和实用的偏高岭土基建筑材料方面的潜力。

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

Ain Shams Engineering Journal Engineering-General Engineering

CiteScore

10.80

自引率

13.30%

发文量

441

审稿时长

49 weeks

期刊介绍： in Shams Engineering Journal is an international journal devoted to publication of peer reviewed original high-quality research papers and review papers in both traditional topics and those of emerging science and technology. Areas of both theoretical and fundamental interest as well as those concerning industrial applications, emerging instrumental techniques and those which have some practical application to an aspect of human endeavor, such as the preservation of the environment, health, waste disposal are welcome. The overall focus is on original and rigorous scientific research results which have generic significance. Ain Shams Engineering Journal focuses upon aspects of mechanical engineering, electrical engineering, civil engineering, chemical engineering, petroleum engineering, environmental engineering, architectural and urban planning engineering. Papers in which knowledge from other disciplines is integrated with engineering are especially welcome like nanotechnology, material sciences, and computational methods as well as applied basic sciences: engineering mathematics, physics and chemistry.