Mix Optimisation and Bending Behaviour of Cement Composites Reinforced with 3D Textiles and Microfibres

In Textile Reinforced Cementitious (TRC) composites, cementitious elements are reinforced with fibre textiles instead of corrosion-prone steel reinforcement. This allows for a considerable reduction of the cross-section of the cementitious elements, and so of the required amount of cement. One of the drawbacks of brittle materials, however, is the occurrence of wide cracks, requiring proper repair. In the presented research, 3D textiles are used as reinforcement in combination with microfibres to design a smart material with self-healing features. The use of 3D textiles has demonstrated a superior flexural behaviour in comparison to 2D textiles, while the short microfibres are known to limit the width of the cracks in the cementitious matrix. These narrow cracks can be healed through the autogenous healing characteristic of the cementitious material. In this research, the synergetic interaction between the 3D textiles, microfibres and cementitious matrix is investigated for the first time. First, the optimal material composition of 3D TRC composites with integrated polypropylene (PP) microfibres of 6 mm (PP6) and 8 mm (PP8) length was explored. This resulted in an optimal fibre content of 0.7 v% for both fibre lengths, allowing sufficient fibre penetration through the 3D textile meshes. Then, the loadbearing behaviour and crack formation of these material compositions were studied by four-point bending tests, monitored with Digital Image Correlation (DIC). The 3D TRC + PP6 samples demonstrated superior flexural properties, and showed slightly more and narrower cracks.