3D 프린팅용 시멘트 계열 재료의 레올로지 정수를 통한 오픈타임 평가

초록

This study evaluates the open time of cement-based materials for 3D printing using rheological parameters. Open time is a critical property that defines the period during which materials can be extruded while maintaining shape stability. Conventional methods based on slump or yield stress have limitations in reflecting time-dependent structural build-up. Therefore, this study examines the applicability of rheological parameters, including dynamic yield stress, plastic viscosity, thixotropy, and storage modulus(G′), for open time evaluation. Mortar open time was measured using a mortar gun, and its relationship with penetration resistance and rheological properties was analyzed. In addition, a time sweep test was conducted on cement paste to determine percolation time(PT) from the evolution of G′, and its correlation with mortar extrusion time was examined. The results show that open time ends before initial setting, and extrusion time is a more reliable indicator than setting time. Increasing accelerator dosage reduced open time, whereas superplasticizer improved dispersion and extended open time. Although paste PT showed a similar trend to mortar extrusion time, its ability to directly predict mortar extrusion time was limited. These findings suggest that rheological approaches are effective for evaluating open time. However, further refinement is required for direct prediction.

키워드