Experimental Study of Tensile Response of Strain Hardening UHPFRC at Early Age

Abstract

Strain Hardening Ultra High Performance Fibre Reinforced Concrete (SH-UHPFRC), has a high tensile strength (over 10 MPa) and exhibit significant strain hardening (several ‰) under tensile loads. These appealing features make it a suitable material for improving the efficiency and durability of new or existing structures. However, in rehabilitation works, when a layer of a new material is applied on an existing structure, due to restraints from the existing structure, the shrinkage deformations lead to high tensile stresses in the new layer, which can lead to premature cracking. To characterize the effect of the restraining conditions, experimental investigations of evolution of autogenous shrinkage and development of eigenstresses were done using a Temperature Stress Testing Machine (TSTM) at quasi-isothermal curing conditions at 20 o C, from the time of casting. Tests were done at partial and full restraint conditions to study the development of the eigenstresses. The tests with 100% restraint are the first of their kind on SH-UHPFRC and the results show that under full restraint conditions, the material enters into the strain-hardening zone of the tensile response.

Tensile response of UHPFRC under very low strain rates and low temperatures

“…The macrofibers were straight, with l f = 10 mm, d f = 0.2 mm, from Bekaert, Belgium. The materials exhibit a significant strain hardening behavior under tension (1-2‰) [63,64]. The detailed compositions of Mix I and II are given in Table 1 and the properties in the fresh state are given in Table 2.…”

Tensile response of Ultra High Performance PE Fiber Reinforced Concretes (PE-UHPFRC) under imposed shrinkage deformations

“…In both devices, fully sealed specimens of cross-sectional dimensions 50 mm 9 100 mm were used. Further details regarding the TSTM setup can be found in [26][27][28][29].…”