Sustainable 3D printed concrete structures using high-quality secondary raw materials

With the onset of rapid urbanization, modernization of urban centers, and population growth, there has been a consequential increase in consumption and waste generation. Traditional waste treatment methods, such as landfilling or combustion in energy plants, are no longer aligned with the requisites and objectives of sustainable development. In response to this challenge, pioneering researchers have diligently sought innovative approaches to address the issue of waste materials. Within the construction sector, both the academic and industrial realms have made concerted efforts to incorporate high-quality waste materials into concrete production. Empirical findings have substantiated the potential efficacy of recycled materials in formulating structural and specialized concretes. Thus the deliberate inclusion of high-quality waste materials in concrete emerges as a viable strategy to mitigate the waste predicament and advance the cause of sustainability. Furthermore, the rapid evolution of concrete technology has generated substantial interest in 3D concrete printing (3DCP) due to its promising advantages, which encompass cost-effectiveness, expedited construction processes, commendable strength and durability, and reduced waste generation. Consequently, 3DCP has demonstrated significant strides in bolstering sustainability efforts. As a result, the synergistic incorporation of high-quality secondary raw materials within the ambit of 3DCP has risen to prominence as a compelling topic of exploration. This amalgamation not only amplifies the utilization of recyclable solid waste but also harnesses the inherent benefits of 3DCP, thereby extending its positive impact on sustainable development. This chapter offers a comprehensive summary of prior research endeavors focused on integrating high-quality secondary raw materials into 3DCP, with a specific emphasis on secondary supplementary raw materials, recycled aggregates, recycled fibers, and waste materials in the context of geopolymer concrete. It is anticipated that the integration of high-quality secondary raw materials into 3DCP will manifest considerable potential in augmenting the properties of concrete. However, it is underscored that the successful implementation of these secondary materials necessitates meticulous attention and proper mix design optimization, encompassing considerations of mix composition and the judicious use of chemical admixtures to modulate rheological properties and achieve adequate mechanical strength.