Flexural properties of 3D printed graded lattice reinforced cementitious composites using digital image correlation

Three-dimensional (3D) printed polymer-reinforced cementitious composites are expected to be used to improve the ductility of cement-based materials. However, research on the maximum flexural capacity and failure mode of lattice-reinforced cementitious composites remains insufficient. In this study, six types of cells with different volume fractions are designed, and mainly undergo bending and tensile deformation. According to the load characteristics during a three-point bending test, five kinds of graded lattice structures are designed. Moreover, a skin-lattice structure and uniform lattice structure are designed, and plain cement mortar is set to comprehensively evaluate the bending mechanical properties of graded lattice-reinforced cementitious composites. The crack evolution and failure mode of these composites under three-point bending load are studied using digital image correlation (DIC). The results show that compared with the uniform lattice, the graded lattice can improve the maximum bending capacity of cement-based materials, improve their cracking characteristics and failure modes during the bending process, and enhance their toughness while reducing the amount of required material. Compared with the plain cement mortar specimen, the graded lattice-reinforced specimen with the largest bending peak load is found to have a 175% increase in the bending peak load and a significant increase in the bending bearing capacity.