Manufacturing accuracy improvement of concrete product by hybrid additive-subtractive method based on the time-dependent characteristics of cementitious materials

Abstract

Cementitious materials used in 3D printing exhibit significant time-dependent characteristics in terms of early-age rheology and stiffness development that limit high-quality manufacturing. However, the centimeter-level accuracy of concrete 3D printing makes satisfying engineering requirements difficult. To address these challenges, a hybrid additive–subtractive method was developed in this study to improve the accuracy of manufacturing concrete products. The printed components were subjected to a cutting/grinding subtractive treatment until their actual dimensions matched the design dimensions within acceptable tolerances. The processing error of the method was quantitatively analyzed using 3D laser-scanning technology, and the method’s effectiveness was validated by conducting various case studies. The results indicated that the manufacturing mismatch can be controlled within a range of 2 mm, and the surface roughness of the components can be reduced from 8.5 mm to 0.5 mm, resulting in a 94.12 % increase. Thus, the proposed method can be used in the high-precision construction of various free-form structures.