High performance fibre reinforced concrete (HPFRC) represents an important innovation in the field of construction materials with a high potential of application . The inherent brittleness of the matrix of this type of concrete may be partly compensated by the addition of fibres, which allows increasing ductility at the cracked state depending on the type and content of fibres used.
E. Galeote (H) • A. Blanco • A. de la Fuente • S.H.P. Cavalaro Department of Civil and Environmental Engineering,
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P. Serna et al. (eds.), Creep Behaviour in Cracked Sections of Fibre Reinforced Concrete, RILEM Bookseries 14,
The effect of creep in concrete is of paramount importance and should not be ignored in design since extreme deformations can compromise serviceability . Unfortunately, there is not a specific criterion to evaluate this effect neither in guidelines nor in codes. The lack of a unified methodology hinders the analysis of results already published due to the significant differences on the methods used. Besides, the long time required to evaluate creep makes its research less common due to the difficulty in obtaining results. However, some studies about creep may be found in both cracked and non-cracked sections in fibre reinforced concrete (FRC) [3-5].
The main aim of this research was to develop a new method capable of measuring the deformation produced by creep in slender elements. For this reason, a steel frame able to hold up to 12 beams was designed and constructed. This structure is based on a system of levers to transmit the load to the mid-span of the beams and includes an acquisition data system to measure the deflection at the central section of the beam. The primary advantage is that this structure enables to load and measure the deformation of each beam individually. Such a type of frame allows to independently customize the load to test each beam without interfering on the others.
An experimental program was conducted to analyse both the performance of the structure and the creep in HPFRC beams. The analysis of creep involved the manufacturing and testing of 12 beams with a height of 40 mm, a width of 80 mm and a length of 1200 mm with two different types of fibre reinforcement and two different curing processes in a pre-cracked state. Additionally, and as a result of the post-peak behaviour of the beams during the pre-cracking process, different load levels were applied onto the beams.