ECCSrm: A novel meso-scale finite element model to simulate shrinkage of engineered cementitious composites (ECCs) incorporaring fiber characteristics

Shrinkage adversely affects cementitious materials' durability and mechanical properties, including Engineered Cementitious Composites (ECCs). It is widely accepted that the fibers in ECCs can resist the plastic shrinkage process. However, there still needs to be more theoretical understanding and modeling capabilities to elucidate the effects of fiber. To this end, a meso-scale finite element model for ECC shrinkage (ECCSrm) is proposed. ECCSrmis developed by combining stresses from humidity losses and a novel fiber generation algorithm (FGA). FGA is developed to generate individual solid fibers with diverse characteristics (length, volume ratio, coordinates, and orientation) (n + 1)D freedom. This study then presents a comprehensive investigation into the predictive capabilities of ECCSrm. ECCSrm was validated through experimental comparisons, demonstrating its effectiveness in accurately predicting drying shrinkage behaviors over time and ultimate shrinkage strains with the within error of 1 %. Further enhancements using extended FEMs enabled a detailed parameter analysis, investigating the effects of fiber characteristics-including different lengths (6 mm, 9 mm, 12 mm, 15 mm, 18 mm), volume fractions (0 %, 0.5 %, 1 %, 1.5 %, 2 %), and types (PVA, PE, PP, basalt)-on drying shrinkage strain. The results indicate that reducing fiber length and altering fiber coordinate distribution have minimal effects on the ultimate drying shrinkage strain, with maximum impacts of 1.56% and 3.13 %, respectively. Increasing the fiber volume fraction can reduce ECC's ultimate drying shrinkage strain but with a boundary effect. Among different fiber types, higher fiber elastic modulus correlates with more minor ultimate drying shrinkage strain in ECC. ECC using PE fibers mainly demonstrates the most minor ultimate drying shrinkage strain, reducing it by 26.39 % compared to ECC without fibers. Fibers at the prism's edges exhibit stronger resistance to drying shrinkage than those in the center. The resistance of ECC to drying shrinkage is inversely correlated with the angle between fiber orientation and the axial direction of the prism.