This paper addresses the uniaxial tensile response of Strain Hardening Ultra High-Performance Fiber Reinforced Concretes (SH-UHPFRC) subjected to very low strain rates and low temperatures. The influence of four different strain rates; 1 × 10 −5 , 1 × 10 −7 , 1 × 10 −8 and 5 × 10 −9 1/s on the tensile properties like elastic limit, elastic modulus, tensile strength and the strain at tensile strength, was studied for two types of SH-UHPFRC mixes; Mix I with type I cement and silica fume, and Mix II with silica fume and 50% mass replacement of type I cement with limestone filler, at three curing temperatures; 20°C, 10°C and 5°C. The tests at strain rates lesser than 1 × 10 −6 1/s are the first of their kind for UHPFRC materials and the results show a considerable impact on the elastic limit of the mixes. Acoustic Emission tests were also carried out for validation of test results of the elastic limit.

No abstract

No 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.

No abstract