Cracking behaviour of textile-reinforced concrete with varying concrete cover and textile surface finish

Abstract

The cracking behaviour of textile-reinforced concrete (TRC) impacts the serviceability and structural integrity of TRC beams. However, textile reinforcement has not yet been standardised and there are numerous available textile reinforcement options. In spite of evidence that the textile properties influence the cracking behaviour of TRC, knowledge of the role of the textile, concrete and geometric parameters on cracking is still limited. This paper investigates a commonly used subset of textile reinforcements, namely epoxy-impregnated textiles with a high yarn count, some of which are prone to induce splitting failure. Through a comprehensive experimental study of 144 uniaxial reinforced concrete tensile tests, the influence of the textile fibre strand geometry and surface finish (plain or sand-coated) on the cracking behaviour was investigated in dependency of the concrete cover thickness. The results show that sand-coating treatment can decrease the transverse crack width to one-third of those observed in analogous plain textile specimens. The geometry of the plain fibre strands, which is affected by the textile fabrication method, also leads to significant differences in the measured crack widths (factor of 2.5). The overall cracking behaviour, however, is decisively influenced by the occurrence of splitting (longitudinal) cracks in the layer of the textile reinforcement, which were observed regardless of the surface treatment for concrete covers thicker than 15 mm. In case of the sand-coated textiles, these splitting cracks initiated immediately after the first main crack and propagated throughout the specimen, which diminished any tension stiffening effects. In the plain textile samples, the cracks led to an excessive spalling of the concrete cover. The results of this study provide a deeper understanding of the cracking behaviour of TRC with epoxy-impregnated textiles and a comprehensive database for further research. This establishes the basis for unified regulations for the limit states of TRC structures.