关键词: 3D打印混凝土, 增强增韧, 多筋同步置入, 水泥基材料, 力学性能, 配筋率

Abstract: The synchronous strengthening method of continuous micro-cable meets the flexibility requirements of 3D printing technology of concrete and can effectively improve the strength and ductility of 3D printed concrete structures. To further improve the bearing capacity of 3D printed concrete structures, a synchronous multi-cables reinforcement method of 3D printed concrete was proposed. Optimizing the multi-cables synchronous embedding process, pull-out tests were carried out to study the bonding characteristics between multi-cables and matrix material. Four-point bending tests were carried out study the effect of reinforcement ratio on the bending performance, and the formula for calculating normal section capacity and oblique section capacity of multi-cables reinforced 3D printed concrete beams was established. The results show that the pull-out of micro-cable damages the matrix material, then reduces the bonding strength between the remaining micro-cables and the matrix material, and decreasing range increases with the decrease of the micro-cables spacing. The maximum decrease is 43.7% when the micro-cable spacing decreases to 4 mm. When the reinforcement ratio of specimen increases from 0.17% to 0.75%, the ultimate bearing capacity of specimen increases by 220.0% under bending load. The established calculation formula has good accuracy for predicting the normal section capacity and oblique section capacity of multi-cables reinforced 3D printed concrete beams.

Key words: 3D printed concrete, reinforcing and toughening, multi-cables synchronous embedding, cementitious material, mechanical property, reinforcement ratio