Influência do volume de pasta, baixo teor de cimento e comprimento da fibra de polipropileno na retração plástica e na resistência verde de materiais cimentícios impressos em 3D

Abstract

Automation in civil construction, especially through 3D printing, emerges as a promising solution for increasing productivity, enabling the manufacture of three-dimensional structures directly from digital models. However, 3D-printed concrete is subject to rapid evaporation of water from the pores immediately after extrusion, which favors the occurrence of plastic shrinkage and the formation of cracks, which can compromise the durability, functionality, aesthetics, and structural stability of the elements produced. In this study, an experimental

method was used to determine the green strength and plastic shrinkage deformations in 3D- printed cementitious mixtures. The study evaluated the effects of partially replacing cement

with supplementary cementitious materials, such as limestone filler and metakaolin, varying the paste volume by increasing the aggregate content, and incorporating polypropylene fibers. The results indicated that reducing the cement content and paste volume contributed to decreasing plastic shrinkage. Furthermore, the incorporation of polypropylene fibers proved highly effective in controlling plastic shrinkage and increasing green strength, even under conditions of higher water evaporation rates, by promoting mechanical restraint and stress redistribution in the fresh state.