Feasibility study of NHL-based grouting materials for crack repair in masonry heritage structures under humid conditions

• Published in: Construction & building materials Vol. 496; p. 143783
• Main Authors: Guo, Anqi, Xu, Shuqiang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 24.10.2025
• Subjects: Expansive agent; Grouting; Masonry heritage; Natural hydraulic lime; Silica fume; Masonry heritage; Natural hydraulic lime; Grouting; Expansive agent; Silica fume
• ISSN: 0950-0618
• DOI: 10.1016/j.conbuildmat.2025.143783

Numerous masonry cultural relics scattered across China possess significant historical, artistic, and scientific values. However, a substantial portion of these artifacts have been subjected to prolonged exposure to humid environments, leading to the development of various forms of deterioration. These conditions severely compromise their structural stability and long-term preservation. The manifestation of cracks represents a prominent example of such conditions. Currently, grouting stands as one of the primary methodologies employed to address crack propagation. Due to its distinctive physicochemical properties, natural hydraulic lime demonstrates significant advantages in this domain. Consequently, natural hydraulic lime is increasingly recognized as an ideal material for the restoration and reinforcement of cultural relics in humid environments, offering both efficacy and compatibility with heritage conservation principles. In this study, natural hydraulic lime was selected as the primary research subject, with silica fume and polycarboxylate ether superplasticizer utilized as modifying agents. Additionally, a CaO-type expansive agent was incorporated to mitigate material shrinkage. The effects of these admixture components on the physical properties, mechanical performance, durability, and microstructure of the system were comprehensively investigated. Furthermore, the applicability of this grouting system for the preservation of masonry cultural relics in humid environments was evaluated using Tomb No. 2 of the Gao Mausoleum as a representative case study, thereby providing valuable references for related research and practical applications in the field of cultural heritage conservation. •Incorporation of SF, PCE and CaO-EA reduced the bleeding and shrinkage of NHL-based grout.•The admixtures accelerated setting process and enhanced strength of NHL-based grout.•NHL-based grouting material was suitable in masonry heritage under humid conditions.