Abstract
Alkali-activated mortar (AAM) has emerged as a sustainable alternative to ordinary Portland cement (OPC) for rock-based applications, yet its bonding behavior with rock remains underexplored. This study investigates the interfacial performance between AAM and sandstone through orthogonal experiments, Brazilian splitting tests, and microstructural analyses (SEM-EDS, XRD). Results show that binder formulation and mortar composition significantly affect bond strength: slag content dominates early-age bonding, while the binder-to-sand ratio controls long-term strength. The optimal mixture (80% slag, water-to-binder ratio 0.35, binder-to-sand ratio 1.5) achieved a 28-day bond strength of 2.67 MPa, surpassing the sandstone’s tensile strength (2.42 MPa). Failure mode shifted from interfacial debonding to cohesive fracture within sandstone, accompanied by a wider interfacial transition zone (ITZ), indicating enhanced physicochemical integration. These findings improve the scientific understanding of the bonding mechanism between AAM and rock and may provide useful implications for rock engineering applications.
Similar content being viewed by others
Funding
The authors would like to acknowledge the financial support provided by the National Post-Doctor Regulatory Commission (No. 333795), the National Natural Science Foundation of China (Grant No. 52104094 & 42272333) and the Central Government Funding Program for Guiding Local Science and Technology Development (2025ZY01028).
Author information
Authors and Affiliations
Corresponding author
Ethics declarations
Competing interests
The authors declare no competing interests.
Additional information
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, which permits any non-commercial use, sharing, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if you modified the licensed material. You do not have permission under this licence to share adapted material derived from this article or parts of it. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/.
About this article
Cite this article
Wang, T., Xu, X., Xue, F. et al. Study on the bonding performance and micromechanism between alkali-activated mortar and rock. Sci Rep (2026). https://doi.org/10.1038/s41598-026-48531-1
Received:
Accepted:
Published:
DOI: https://doi.org/10.1038/s41598-026-48531-1
