Development of a sustainable concrete mix using rice husk ash and steel slag for 3D printing

Abstract

Three-dimensional printing has emerged as a transformative technology in the construction industry, offering efficiency and reduced reliance on labour. The automated process of 3D concrete construction, particularly through contour crafting, has minimized labour requirements, eliminated the need for formwork, and garnered acclaim for its sustainability. However, challenges persist, with the choice of proper mix design and materials standing out as a critical factor. This research addresses a significant challenge in 3D concrete technology the excessive use of cement and chemical admixtures. While previous studies have explored partial cement substitution, little attention has been given to replacing fine aggregate. This research focuses on substituting rice husk ash for cement, emphasizing the contribution to bio- concrete by offsetting carbon dioxide emissions. The use of rice husk ash, a well- studied material, aims to enhance workability and flowability. Furthermore, the study introduces the novel concept of substituting fine aggregate with steel slag, a construction waste material. This collaboration between rice husk ash and steel slag presents a unique challenge due to the irregularities in shape, water absorption properties, and porosity of steel slag. The research aims to analyse the behaviour of 3D concrete in both fresh and hardened states when these two components are combined as partial replacements. The research aims to identify the optimum replacement percentage of steel slag as fine aggregate in 3D concrete, supplemented by a partial substitution of a bio-based cementitious compound. The study explores the rheological behaviour of the fresh concrete, laying the groundwork for future modifications. Objectives include introducing 3D concrete to the Sri Lankan construction industry, replacing fine aggregate with steel slag, employing cost- effective testing methods for rheological properties, and incorporating rice husk ash as a partial replacement for cement. This research contributes to the sustainable development of 3D concrete technology, offering insights into material substitutions that enhance environmental and economic aspects, making it a valuable endeavour for the construction industry