Rheological Behavior of 3D Printable Bio-Concretes Produced with Rice Husk

Abstract

This article presents an investigation on the rheological behavior of 3D printable bio-concretes containing rice husk fine particles. This agro-industrial waste was used to adjust the fresh-state properties of the concrete mixture, required for the printing process, while decreasing its environmental impact. In this study, the rice husk content varied from 5 to 12.5%, in mass of solids. The rice husk was submitted to a crushing process and two different particle sizes were investigated. The static yield stress was measured using a rotational viscosimeter equipped with a Vane spindle after different resting times. The results were used to obtain the thixotropic build-up rate and to calculate the printing parameters, such as layer height, time between successive layers and printing velocity. The results showed that the use of rice husk increases both the initial yield stress and the thixotropic build-up rate of the bio-concretes, which leads to an increase of the maximum layer height and the maximum printing velocity. Finally, the results showed the feasibility of using biomass for improving the buildability and printability of the mixtures.