Printability of magnesium potassium phosphate cement with different mixing proportion for repairing concrete structures in severe environment

It is well acknowledged that the of design concrete structures in the severe conditions such as marine environment has more challenges compared with those constructed in normal circumstances. The demand of fast repairing type materials and its utilization has becoming increasingly significant due to the less durability of the concrete under serious service conditions. The combination of rapid hardening cement with 3D printing technology expands a new area of producing repairing materials in severe environment because 3D printing technology has its unique advantages of producing structural members without casting and assembling. The main purpose of the paper is to examine the printability of Magnesium Potassium Phosphate Cement (MKPC) which as a fast repairing material contributed to maintain the concrete structures in any serious environment. By analysing printed specimens produced by different mixing proportion of MKPC powder, an optimal formulation of suitable combination of the MKPC powder was suggested to improve the printability of the applied materials. Furthermore, Water drop penetration behaviour and different particle size of MKPC powder would also influence the degree reaction between KDP and MgO. Finally, a broad of droplet tests were carried out to obtain an optimized printing nozzle with the inner diameter of 0.06mm which could produce one printable layer with width of 0.9mm.