Eco-friendly 3D printed concrete with fine aggregate replacements: Fabrication, characterization and machine learning prediction

Abstract

During the last decade, 3D printing technology has experienced significant development, especially for concrete printing in construction. However, eco-friendly 3D printed concrete with fine aggregate replacements has not yet been sufficiently studied. Herein, twenty-five (25) mix categories are designed for use in 3D printed concrete. The mix materials include fine aggregates, silica fume (SF), ground waste rubber tire (Ru), and glass fiber (GF) composites. The mechanical characterization (i.e., stress-strain relations) are investigated, and the mechanical performance (i.e., compressive and flexural strengths) are reported. Numerical simulations are carried out to validate the experimental results, and satisfactory agreements are obtained. Machine learning prediction model is developed using the experimental and numerical results to predict the compressive and flexural strengths of the aggregate-mixed 3D printed concrete. An inverse relationship was observed between the rubber content and compressive strength of 3D printed concrete (RuC) printing imperfections is highly correlated with high rubber content. Similarly, increasing fiber volume in fiber concrete (FC) resulted in a decreased compressive strength due to reduced interlayer bond. Notably, hybridized concrete (HC) exhibited comparable strengths to fiber concretes at 1% fiber content, but a significant strength increase was observed at 5%, 10%, and 15% rubber contents with 2.5% fiber volume. Better stress-strain response (i.e., higher strength) is observed with larger SF content. It is evident that the addition of SF, GF, and Ru to concrete, improves cost efficiency and the stress-strain behavior of 3D printed concrete. The reported eco-friendly 3D printed concrete has a relatively low peak strength compared to normal concrete but shows traces of fatigue resistance. The eco-friendly 3D printed concrete provides the alternative for normal concrete for in-situ construction applications.