Reviewed by Lexie CornerJan 24 2025
In a recent study published in the journal Engineering, researchers from Hohai University, Northwestern University, and Politecnico di Milano have developed a novel mesoscale mechanical discrete model called LDPM-MicroF to model the fracture behavior of microfiber-reinforced concrete (FRC).
(a) Load and constraint; (b) coarse aggregate distribution; (c) parallel fiber distribution in tension direction; (d) random fiber distribution. Image Credit: Lei Shen et al.
Microfibers are under 100 µm in diameter. They are critical for reducing pore pressure during fires and preventing early shrinkage cracking. However, accurately modeling micro-FRC has been challenging due to high computational costs and the complexity of physical mechanisms.
The LDPM-MicroF model addresses these issues by introducing an equivalent fiber diameter coefficient (rf), balancing accuracy and computational efficiency. This allows for simulations of mechanical responses in engineered cementitious composites and explains the unimodal variation in tensile strength with increasing microfiber dosage.
The model was validated through direct tension tests on concrete with micro-polypropylene (PP) fibers. By adjusting rf, it aligned with experimental data for both parallel and randomly oriented fiber distributions and correctly predicted strength changes in steel and micro-PP FRC splitting tension tests.
LDPM-MicroF successfully captured the behavior of micro-PP FRC, where splitting tensile strength increased and then decreased with fiber volume fraction. In four-point bending tests of micro-basalt FRC, the model accurately replicated cracking patterns and unimodal strength distribution.
The model also demonstrated its ability to handle high microfiber dosages in ECC tension tests while significantly reducing computation time with optimized rf.
This study enhances understanding of micro-FRC mechanics by incorporating the “near-field effect” of microfibers and distinguishing regions of fiber intersections from effective matrix areas on cracks. These insights provide a foundation for future research and practical applications in cementitious composites.
Journal Reference:
Shen, L., et al. (2024) Mesoscale Mechanical Discrete Model for Cementitious Composites with Microfibers. Engineering. doi.org/10.1016/j.eng.2024.11.017.