Chen et al. (2026) — To achieve high tensile strain capacity in cementitious composites

Citation

Jiaxin Chen, Zhuoma Basang, Runting Wang, Ning Dai, Fangming Jiang, Fei Wang, Jianzhuang Xiao, Kequan Yu, Jiangtao Yu (2026). To achieve high tensile strain capacity in cementitious composites. Composites Part B: Engineering, Vol. 318, Article 113639.

DOI: 10.1016/j.compositesb.2026.113639
Atlas layer: extension
Related Victor Li book chapter: Chapter 2: Micromechanics and Materials Design; Chapter 3: Tensile Strain-Hardening Criteria; Chapter 4: Extreme-Ductility ECC
Source PDF: chen-2026-to-achieve-high-tensile-strain.pdf
Extracted text: atlas/full_text/chen-2026-to-achieve-high-tensile-strain_full_text.md
Source note: atlas/source_notes/chen-2026-to-achieve-high-tensile-strain_source_note.md

Why this paper matters

Reveals the mathematical and physical mechanisms governing high tensile strain capacity (>6–12%) in cementitious composites, proving that debonding-pullout (DP) fibers minimize statistical dispersion losses, and discovering that mixing-induced bamboo-like nodular protrusions on UHMWPE fibers enhance bridging by 33.9% while fiber end-slip induced micro-pores lower adjacent matrix cracking strength to generate spatially correlated crack bands.

Main contribution

Mathematical formulation of fiber failure modes: Showed that debonding-rupture (DR) fibers suffer a 30% reduction in integrated bridging capacity under realistic statistical variations, whereas debonding-pullout (DP) fibers (UHMWPE) lose only 4.28%.
Fiber distribution density scaling: Formulated why large-diameter steel fibers ($250\ \mu\text{m}$) exhibit 10-fold higher bridging strength variability than fine PE fibers ($25\ \mu\text{m}$), capping UHPC ductility at $0.8\%\text{--}1.2\%$.
Discovery of bamboo-like nodular morphology: Discovered that mixing shear buckles UHMWPE fibers into $3\ \mu\text{m}$ periodic nodular protrusions ($73\ \mu\text{m}$ spacing), enhancing single-fiber pullout peak load by 28.3% and mean bridging strength by 33.86%.
Mechanism of crack spatial correlation: Proved that fiber end-slip leaves $10\text{--}100\ \mu\text{m}$ micro-pores near fiber tips, reducing local matrix cracking strength by $\ge 15\%$ and promoting saturated multi-crack banding.

Evidence summary

Statistical simulation:
PVA (50% DR + 50% DP): Bridging strength drops by 30.0% ($322.1 \rightarrow 277.5\text{ N}$) and CMOD drops by 51.0% due to dispersion (Table 4, Fig. 4).
UHMWPE (100% DP): Bridging strength drops by only 4.28% ($394.4 \rightarrow 377.5\text{ N}$) under identical dispersion.
Micro-fine steel vs UHMWPE: At $V_f = 1.5\%$, PE fiber ($25\ \mu\text{m}$) yields $\text{COV}{fb} = 0.008$ and predicted strain capacity of $15.9\%$, whereas steel fiber ($250\ \mu\text{m}$) yields $\text{COV} = 0.084$ and strain capacity of $0.53\%$ (Tables 6, 7, 8, Figs. 5, 7, 8).
Single fiber pullout: Mixing-induced bamboo-like protrusions increase peak load by 40% ($2\text{ mm}$), 27% ($6\text{ mm}$), and 18% ($10\text{ mm}$) (Table 10, Figs. 9, 10).
Crack correlation: 70.0%–87.5% of cracks with lower subsequent cracking strength were spatially correlated within $\pm 9\text{ mm}$ of existing cracks, driven by $10\text{--}100\ \mu\text{m}$ fiber end-slip pores verified via XCT/MIP (Tables 11, 12, Figs. 11, 12, 13).

Linked Atlas nodes

02_concepts/strain_hardening_criteria.md
02_concepts/fiber_bridging_law.md
02_concepts/extreme_ductility_ecc.md
02_concepts/flaw_design.md
05_experiments/direct_tensile_test.md
05_experiments/single_fiber_pullout.md

Claim-evidence rows to add

Atlas node	Claim	Evidence summary	Page/Figure/Table	Status
`02_concepts/extreme_ductility_ecc.md`	Pure debonding-pullout (DP) fibers such as UHMWPE maintain high bridging strength and CMOD tolerance under statistical dispersion (4.28% reduction vs 30% in DR fibers), enabling extreme tensile strain capacity exceeding 6–12%.	Stochastic numerical simulation and single-fiber pullout models verified DP fiber tolerance to parameter dispersion.	Pages 1, 5, 6, Section 2.1 & Abstract, Table 4, Fig. 4	verified_from_pdf
`02_concepts/fiber_bridging_law.md`	Mechanical mixing induces periodic bamboo-like nodular protrusions on UHMWPE fibers (3 µm height, 73 µm spacing), increasing single-fiber pullout peak load by 28.3% and mean composite bridging strength by 33.9%.	OM, SEM, single-fiber pullout tests (2–10 mm embedment), and bridging simulations confirmed 28.3% load increase and 33.86% bridging strength increase.	Pages 10, 11, 12, Section 3.1, Tables 9, 10, Figs. 9, 10	verified_from_pdf
`02_concepts/flaw_design.md`	Fiber end-slip during tensile debonding creates 10–100 µm micro-pores at fiber tips within ±9 mm of bridged cracks, lowering local matrix cracking strength by ≥15% and inducing spatially correlated crack bands.	DIC strain tracking, XCT/NMR/MIP porosity measurements, and stochastic multi-cracking modeling confirmed 70–87.5% correlation and 38.5% ductility boost.	Pages 12, 13, Section 3.2, Table 12, Figs. 11, 12, 13	verified_from_pdf

Verification status

PDF preserved: yes (chen-2026-to-achieve-high-tensile-strain.pdf)
Text extracted: yes (atlas/full_text/chen-2026-to-achieve-high-tensile-strain_full_text.md)
DOI verified: yes (10.1016/j.compositesb.2026.113639)
Page/figure/table verified: yes
Claim-evidence matrix ready: yes

Cautions

Mathematical models assume idealized straight fiber geometries and omit severe fiber balling or agglomeration effects.