3 rd International Conference on Bio-Based Building Materials June 26 th - 28 th 2019 Belfast, UK 725 ID_ JJJJJ223 FIRE BEHAVIOUR OF BIOBASED TEXTILE REINFORCED CEMENT COMPOSITES J.Claramunt 1 *, L. Haurie 2 , L. Gonzalez-Lopez 3 , H. Ventura 3 , M. Ardanuy 3 * 1 Universitat Politècnica de Catalunya, Departament d’Enginyeria Agroalimentària i Biotecnologia, Barcelona, Spain 2 Universitat Politècnica de Catalunya, Departament de Tecnologia de l’Arquitectura, Barcelona, Spain 3 Universitat Politècnica de Catalunya, Departament de Ciència dels Materials i Enginyeria Metal·lúrgica, Barcelona, Spain *Corresponding author; e-mail: monica.ardanuy@upc.edu Abstract Our research group has recently developed a composite laminate reinforced with flax fibre nonwoven fabrics with a flexural strength of around 30 MPa and a toughness of around 13 kJ/m 2 , owing to the combination of a strong fibre-matrix bonding and the use of entangled fibres. The mechanical performance of the cement composites developed fulfils the requirements for applications in panels for ventilated façades, but the fire behaviour was not been yet studied. Hence, this work focuses on the analysis of the performance of these composites at high temperatures. For this purpose, flax nonwoven reinforced calcium aluminate cement (CAC) composites with variable metakaolin content (from 10 to 40%) have been prepared and characterized. In order to evaluate the effect of temperature on the mechanical properties, the different samples were exposed to temperatures of 250 ºC, 450 ºC and 950 ºC, and were further subjected to bending tests. As a main conclusion, the presence of natural fibres do not seem to worsen the fire behaviour of the CAC/metakaolin composites. Keywords: Fire behaviour; Flax fabrics; Cement based composites; Façade panels 1 INTRODUCTION A ventilated façade is a construction system for the enclosure of a building. It consists of a ventilated air chamber between an external cladding and the wall of the building. The main advantage of ventilated façades is their good thermal performance. The continuous thermal insulation minimizes thermal bridges, and the air chamber allows natural ventilation. However, in case of fire the chimney effect of the air chamber will contribute to the fire propagation [Giraldo 2013]. Therefore, ventilated façades must incorporate some measures, such as fire barriers, to avoid fire spread. In this context, the use of non-combustible materials is another strategy to improve the fire performance of the façade. Composite materials of cement matrix and natural fibre reinforcements are a good alternative for the external panels of ventilated façades, since they are lightweight and have good mechanical properties [Claramunt 2016a]. Nonetheless, durability of vegetal reinforced cements is a widely known problem [Almeida, 2013; Santos, 2015; Wei, 2015], mainly because of the alkaline environment resulting in the degradation of the cellulosic fibres. Thus, one of the strategies to avoid this is the substitution in the matrix of Portland cements by calcium aluminate cements [Claramunt 2018]. Although the mechanical performance of these cement composites has been assessed in a previous work, the requirements for applications in panels for ventilated façades, the fire behaviour of these materials has not been studied yet. Hence, this work focuses on the analysis of the performance of these composites at high temperatures. 2 MATERIALS AND METHODS 2.1 Materials The calcium aluminate cement (CAC) used as matrix was provided by Grupo Cementos Molins (Barcelona, Spain), and the metakaolin (MK) by Arcillas Refractarias S.A. (Gijón, Spain). Flax fibers of a length of 60 mm, from Fibers Reserche Development of the Technopole de l’Aube en Champagne (France), were used for the production of the nonwoven reinforcing fabrics under the methodology defined in previous works [Ventura, 2014]. This nonwoven presents 2 mm of thickness and 275 g/m 2 of areal weight. 2.2 Dosage and sample preparation Panels of 300x300 mm 2 and 10 mm thickness were produced. For the matrices, pastes of CAC with MK contents between 0 and 40 wt. % were prepared with a water/cement ratio of 2. Samples were obtained by a laminate technique with 5 layers of nonwoven fabric