Abstract The anchor design for Low-Carbon Concretes still lacks parameters that link microchemistry to structural performance. This work introduces a microstructural coefficient η, defined from gel density and interfacial porosity of the N-A - S-H / C - A - S-H networks, to extend the classical Tepfers. The analytical derivation shows that η multiplies the circumferential stress solution without altering its geometric scale, predicting a linear increase in initial stiffness and anchor energy. Three-dimensional bar–matrix contact simulations (FEniCS) for =1. 0-1. 6 η = 1. 0 - 1. 6 and two cover ratios = d/c = 0. 20, \;0. 14 λ = d / c = 0. 20, 0. 14 confirmed this prediction within 3 % for peak hoop stress and 2 % for secant stiffness. A 2 3 2 × 3 factorial pull-out program on fly-ash concretes (two covers, three Si / Al ratios) experimentally validated the proportionality K ₄ₗ = K₀ K exp = η K 0 experimentally; two-way ANOVA ranked gel chemistry as the dominant factor, explaining up to 93 % of stiffness variance at 28 days, while residual errors remained negligible. The metric sweeps of the fracture number κ and the friction number Re Re μ confirmed that η governs the stiffness, κ controls the post-peak toughness and Re Re μ scales the residual plateau, delineating a domain of validity of 1. 6 η ≤ 1. 6, 0. 004 κ ≥ 0. 004, 0. 12 0. 25 0. 12 ≤ λ ≤ 0. 25. These convergent results demonstrate that a single parameter captures the chemomechanical enhancement of alkali-activated concretes, providing a direct calibration rule that can be incorporated into future revisions of the ACI 323 Low-Carbon Concrete code.
Rúa-Patiño et al. (Sat,) studied this question.