Mechanical strengths and optical properties of translucent concrete manufactured by mortar-extrusion 3D printing with polymethyl methacrylate (PMMA) fibers

Abstract

Manufacturing conventional translucent concrete consumes lots of labors and formworks. To solve this problem, novel translucent concrete was proposed and manufactured in this work by mortar-extrusion 3D printing, which used polymethyl methacrylate (PMMA) fibers to transmit light and also reinforce the printed concrete. The printing procedures started by extruding one-layer mortar first, and then the fibers were placed on top the printed mortar. Afterward, repeated the above two steps multiple times. The printability, mechanical strengths, optical properties and micro characteristics of the printed translucent concrete were tested. Results showed the fibers increased the buildability and anisotropy of the printed specimens. Specifically, in comparison with the printed specimens without fibers, the flexural strengths of the printed translucent concrete with fibers increased when loading perpendicular to the fiber orientation, whereas those in other loading directions decreased. The fibers also increased the compressive strengths of the printed specimens when loading perpendicular to the fiber orientation, but decreased those in loading parallel to the fiber orientation. Light transmittance of the fibers in the printed translucent concrete was also studied. Results showed reflection coefficients of concrete, fiber diameters, light incident angles influenced the light transmittance. Generally, the light transmittance increased with the reflection coefficients and fiber diameters but decreased with the light incident angles. And the incident angles, which were affected by the printing quality, influenced the light transmittance more than other two factors did. The results and methods in this work can help to increase the efficiency of manufacturing translucent concrete.