Experimental study on flexural behavior of precast ultra-lightweight ECC plank with lattice girder at construction stage

During the construction of precast concrete (PC) structures, concrete composite slabs are commonly used, employing PC planks with lattice girders as permanent formwork to enhance assembly efficiency while ensuring structural performance. However, traditional PC planks suffer from heavy weight and susceptibility to cracking, adversely affecting construction efficiency and quality. This paper proposes the incorporation of ultra-lightweight engineered cementitious composite (ULECC) into PC planks. The research aims to investigate the flexural behavior of precast ULECC planks with lattice girders during the construction stage. Four-point bending tests were conducted to study the effects of lattice girders and ULECC layer. The introduction of ULECC reduced the self-weight of precast planks by 24%, while resulting in a decrease in strength and stiffness due to ULECC's lower elastic modulus. Remarkably, precast ULECC planks exhibited excellent crack width control. Even at a deflection-span ratio of approximately 4%, precast ULECC planks were capable of maintaining crack widths below 0.2 mm. The combination of ULECC and lattice girders significantly improved the structural performance of precast ULECC planks, allowing them to meet construction requirements without requiring temporary support.