Analysis of Curing and Mechanical Performance of Pre-Impregnated Carbon Fibers Cured within Concrete

In carbon-reinforced concrete, the commonly used steel reinforcement is replaced with carbon fiber reinforcement textiles, enabling thin-walled elements by using new construction principles. The high drapability of textiles offers design opportunities for new concrete structures. However, commonly utilized textiles are impregnated with comparatively stiff polymeric materials to ensure load transmission into the textile, limiting drapability. In this paper, a new approach is analyzed: the use of pre-impregnated textiles cured within the concrete matrix. This enables the production of filigree, highly curved components with high mechanical performance, as needed for novel additive manufacturing methods. In the presented trials, rovings were successfully impregnated with potential impregnation materials, cured within the concrete, and compared to rovings cured outside of the concrete. The analysis of the curing process using a rolling ball test determines that all materials have to be placed in concrete 4 to 24 h after impregnation. The results of uniaxial tensile tests on reinforced concrete show that maximum load is increased by up to 87% for rovings cured within concrete (compared to non-impregnated rovings). This load increase was higher for rovings cured outside of concrete (up to 185%), indicating that the concrete environment interferes with the curing process, requiring further analysis and adaptation.