Technical and Environmental Feasibility of Using CFRP Textile as Stay-In-Place Participating Formwork for Shape Optimised Concrete Beams

Shape optimisation of concrete elements will reduce concrete consumption and hence embodied carbon. However, providing both formwork and reinforcement for shape optimised concrete elements is challenging due to their curved geometries. This paper explores a novel design and construction method for shape optimised concrete beams where flexible CFRP textile is used as a stay-in-place participating formwork, i.e. serving as both the formwork and reinforcement. The technical feasibility of the system was assessed by generating a series of beam designs to discuss the scale of the CFRP textiles required. Environmental feasibility was also assessed by estimating the embodied carbon of several designs against conventional beam designs. Due to the lack of readily available options in the present market, further studies are needed to assess the technical feasibility of using CFRP textiles up to 2 mm thick as participating formwork to reinforce beam designs required in practice. Shape optimisation can reduce concrete volume by up to 36% compared to equivalent prismatic beam designs with similar midspan depths. The midspan depth of the design with minimum embodied carbon for a given design criteria may not coincide with the depth of a conventional prismatic beam design, yet embodied carbon reductions up to 33% are possible.