Enhancement of Crack Distribution of UHP-SHCC under Axial Tension Using Steel Reinforcement

Ultra High Performance-Strain Hardening Cementitious Composites (UHP-SHCC) are a composite material comprising a cement-based matrix and short fibers with outstanding mechanical and protective performance. Surface protection repair using a thin layer of UHP-SHCC to extend the service life of concrete structures has been proposed, and surface protection performance associated with both a durable matrix and multiple fine cracks is required. This paper presents an example of decreased cracking ability and decreased strain capacity in UHP-SHCC specimens of a practical size. Note that, the small size dumbbell-shaped UHP-SHCC specimen can exhibit a large number of cracks and higher strain capacity. Also, this paper assesses the usage of a small amount of steel reinforcement in order to enhance the crack distribution and strain capacity of practical size UHP-SHCC specimens in tension. Practical-size specimen dimensions (cross sectional size: 200 x 50mm), which are similar to the typical size used for surface protection repair applications (depth of 30 to 70 mm), were selected in this study. Different reinforcement ratios ranging from 0.3% to 1.2% were used to evaluate the effect of the reinforcement ratio on the specimens' strain capacity and crack distribution.