Autor/a: Marta Caballero Jorna




The addition of fibres to the cement matrix is used since the sixties to take advantage of the benefits they offer in fibres reinforced concrete (FRC) compared to traditional concretes. The technological advances in the construction sector have not stopped since then, managing to introduce different types of fibres into the market. Macrosynthetic fibres appeared more recently than steel fibres and although their behaviour has been studied, the effect of temperature on macrosynthetic fibres reinforced concrete (MSFRC) has not been evaluated yet in depth. Macrosynthetic fibres may be affected by temperature changes since their mechanical properties are thermally dependent which thus has influences on the properties of MSFRCs.
This Master's Thesis analyses the short-term behaviour of MSFRCs at different temperatures. To do this, a common concrete of the prefabricated industry of 35 MPa, with a maximum aggregate size of 10mm and a relatively high fibre content (10 kg/m³) was selected. Threepoint bending test were carried out according to a testing methodology based on the standard UNE-EN 14651:2007+A1:2008 (2/3 scale). This procedure allows to evaluate the mechanical properties of the concrete after reaching its nominal strength and after a conservation period of two months, when the entire mass is at the target temperature as well as the effect of its variation when the concrete is in service condition. The target temperatures were: 5 ºC, 20 ºC, 35 ºC and 50 ºC.
Other options have also been considered like pre-fissuring of the specimens and the use of different types of fibres in order to compare and extrapolate results. Compressive strength and workability of the concrete were used as complementary characterization tests. The results show that moderated temperatures do (to a great extent) not affect performance of macrosynthetic fibre reinforced concrete for this period of conservation, since the shortterm mechanical behaviour (residual flexural strengths) of these materials is quite similar (also compared to other results of FRCs), but it can not be affirm that temperature has not a significant influence. This contribution opens the possibility of continuing to further investigate this.