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. 2026 Jan 21.
doi: 10.1038/s41598-026-36289-5. Online ahead of print.

Coupled effect of unloading rate and water content on mortar under differential cyclic loading

Zhizhen Liu  1   2 , Ping Cao  2 , Lang Liu  1   3 , Fei Wang  4 , Dongya Han  5 , Chongcai Xu  6
Affiliations

Coupled effect of unloading rate and water content on mortar under differential cyclic loading

Zhizhen Liu et al. Sci Rep. .

Abstract

Repeated excavation and fluctuations in water levels subject mortar to varying stress rates and moisture conditions; however, the coupling effects of these factors remain insufficiently studied. This research examines the combined influence of unloading rate and water content on the mechanical behavior of water-bearing mortar (WM) under multi-level differential cyclic loading (MDCL). Experiments were conducted on specimens with three representative water contents (0.00%, 6.99%, and 13.98%) under multiple unloading rates. The results indicate that both factors affect mechanical properties and interact synergistically. Critical thresholds were identified at a water content of 6.99% and an unloading rate of 2.0 kN/s, marking distinct transitions in energy response. A strong linear relationship was observed between cumulative strain increment and the number of MDCL cycles, which may facilitate failure prediction. Both loading and unloading moduli were highly sensitive to moisture content and unloading rate, with MDCL enhancing the overall stiffness of the material. These findings contribute to a deeper understanding of the coupled effects of water content and unloading rates on mortar under MDCL, offering valuable insights for assessing the stability and deformation of WM structures in engineering applications.

Keywords: Damage characteristic; Energy law; Loading and unloading moduli; Modulus coefficient; Multi-level differential cyclic loading; Strain increment; Water-bearing mortar.

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Conflict of interest statement

Declarations. Competing interests: The authors declare no competing interests.

References

    1. Al-Mosawe, H., Albayati, A., Wang, Y. & MashaanN.S. An experimental study of granular material using recycled concrete waste for pavement roadbed construction. Buildings 12 (11), 1926. https://doi.org/10.3390/buildings12111926 (2022).
    1. Gao, X. et al. Determination of dam concrete strength parameters considering the effects of ambient environment, member size and aggregate size: A case study of Baihetan dam. Constr. Build. Mater. 421, 135707. https://doi.org/10.1016/j.conbuildmat.2024.135707 (2024).
    1. Fatemi, H., Hadigheh, S. A., Tao, Y. & Adam, G. Development of a novel and specialised cementitious matrix overlay for anode embedment in impressed current cathodic protection (ICCP) systems for reinforced concrete bridges, case stud. Constr. Mater. 20, e02908. https://doi.org/10.1016/j.cscm.2024.e02908 (2024).
    1. Sun, Z. et al. Electrical resistivity prediction model for basalt fibre reinforced concrete: hybrid machine learning model and experimental validation. Mater. Struct. 58(3), 1–22. https://doi.org/10.1617/s11527-025-02607-y (2025).
    1. Lin, H. et al. Effects of low temperatures and cryogenic freeze-thaw cycles on concrete mechanical properties: A literature review. Constr. Build. Mater. 345, 128287. https://doi.org/10.1016/j.conbuildmat.2022.128287 (2022).