A multiscale local structural derivative model to characterize anomalous diffusion in fresh cement pastes

• Published in: Journal of Building Engineering Vol. 102; p. 111949
• Main Authors: Liu, Yao, Yan, Shengjie, Liang, Yingjie
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.05.2025
• Subjects: Anomalous diffusion; Fresh cement pastes; Local structural derivative; Multiscale; Ultraslow diffusion; Ultraslow diffusion; Fresh cement pastes; Multiscale; Local structural derivative; Anomalous diffusion
• ISSN: 2352-7102; 2352-7102
• DOI: 10.1016/j.jobe.2025.111949

This paper proposes a multiscale local structural derivative model to describe anomalous diffusion in fresh cement pastes, which combines a subdiffusion model in power law form with an ultraslow diffusion model in logarithmic form. The model contains four parameters, diffusion coefficient, characteristic time and two derivative orders, which are verified by using mean squared displacement (MSD) data of particles diffusion in fresh cement pastes at different curing ages. The properties of MSD largely depend on the values of the derivative orders, which results in multiscale diffusion process. Compared with the fractal derivative anomalous diffusion model and local structural derivative ultraslow diffusion model, the proposed model has much lower errors in characterization of the particles diffusion in fresh cement pastes. It also indicates that the particles diffusion exhibits a multiscale feature in the fresh cement pastes, especially in smaller time scales. Interestingly, all four fitted parameters exhibit exponential functions that increase with the curing age and are subject to modification due to external factors affecting the rheology of the cement pastes. •This study proposes a local structural derivative model to characterize anomalous diffusion in fresh cement pastes.•The results show that the proposed model can well fit the data at different curing ages.•The proposed model is feasible in describing the multiscale diffusion behavior of particles in fresh cement pastes.