Experimental study on the size effect of ultra-high ductile cementitious composites

Ultra-high ductile cementitious composites (UHDCC) has strong tensile strain-hardening characteristics, however limited attention was drawn to size effect of this material. To better understand the size effect of UHDCC, this study conducted systematic tests from single crack fracture (determined) to multi-cracking fracture, i.e., 3-point bending test on notched beam, uniaxial tension test on dogbone-shaped specimen, and compression test on UHDCC cube and cylinder. The results indicated that the common fracture-based size effect is negligible in flexural strength and tensile strength, but significant in compressive strength with end-frictional confinement. The size effect in compressive strength of UHDCC is reduced after eliminating end-frictional confinement or adopting specimen with high aspect ratio. Due to the strong fiber slip-hardening behavior, the length of fracture process zone of UHDCC is drastically enlarged, making it insensitive in case of common structure size and the strengthened Weibull statistical size effect. (C) 2019 Elsevier Ltd. All rights reserved.