Effectiveness of Sprayed Strain-Hardening Limestone Calcined Clay Cement (SHLC3) Composites in Retrofitting Concrete-Beams

The attractiveness of strain-hardening cement-based composites (SHCC) in civil engineering applications results from their pseudo-ductile response and multiple fine cracks under tensile loading. Previous research has demonstrated that SHCC show high potential as a repair material for concrete structures. They also hold promise to overcome the current limitations of traditional application techniques, paving the way for advanced automated systems. In this contribution, the effectiveness of a novel SHCC formulation for retrofitting concrete elements is investigated. This formulation is based on limestone calcined clay cement (LC3) and polyethylene fibres. The focus is on the influence of different technological parameters, such as the volume fraction of fibres and the application technique, on the mechanical performance of SHCC. Two different SHCC strengthening systems are developed and applied to the tensile side of concrete beams, either with or without a biaxial carbon textile reinforcement. In total, 18 beams are prepared and subjected to three-point bending (3PB) tests. The influence of the repair systems on the flexural behavior of the retrofitted concrete beams is demonstrated and discussed. The test results reveal that the strengthening layers under investigation significantly improve the flexural performance of concrete beams.