Fiber distribution in strain-hardening cementitious composites (SHCC): Experimental investigation and its correlation with matrix flowability and tensile strength

Abstract

Sectional fiber content variation in strain-hardening cementitious composites (SHCC) governs tensile performance by dictating the bridging capacity of the weakest crack. However, this critical factor has rarely been quantified experimentally. This study systematically characterizes fiber distribution in SHCC with varying matrix flowabilities via sectional analysis. Results show that medium matrix flowability (Marsh cone flow time of around 30 s) results in both uniform fiber dispersion and reduced fiber content variation, thus enhancing tensile performance. Existing Monte Carlo models are found to significantly underestimate the sectional fiber content variations exhibited by test data by over 70 %, highlighting the necessity of this experimental study. Simulations on minimal sectional fiber content based on measured distributions show a strong correlation with experimental median tensile strength ($R^2$ = 0.9538), confirming the tensile behavior depends critically on fiber content variability. This study quantitatively explained the differences in the tensile strength of SHCC with different matrix flowabilities and provided new insights into the relationship between matrix flowability and tensile performance. The measured fiber distributions can facilitate the design, optimization, and modeling of SHCC considering the material processing factors.