Experimental-analytical and digital based investigation of 3D printed sandwich sand mold used for precast structure

The 3D printing technique for sand mold exhibited the good response of precast concrete structure manufacturing process. The designed sandwich core structure, including solid core, diamond core, honeycomb core, pyramid core and round O core were constructed by silica sand with different thickness and different relative density ratios from 0.5 to 0.9 and investigated by mechanical experiment, finite element modeling and digital image correlation. The solid block showed the greatest compressive strength 6.15 MPa and flexural strength 3.85 MPa. The sand core with density ratios of 0.9 performed a significant response with greater 10-50% in strength, compared with specimens with ratios 0.5 and 0.7. The sandwich composites with honeycomb and pyramid core showed a sequence of stability and enhancement with 2-3 times in difference. The experimental, numerical and digital results indicate that the core structure can be optimized to control and apply to 3D printing sand mold and precast concrete structure with a good agreement with under 15% in comparison and verification. These findings offered a good insight into the study of mechanical behavior of sandwich structure in the application and industry.