Progress in construction automation : review on 3D printing of concrete materials

Abstract

3D Printing or additive manufacturing has been gaining popularity in the concrete research community and the field. Compared with conventional vibrating concrete or self- consolidating concrete, 3D printing technique do not require formwork, which is labor intensive and costly in construction sites. With the advantages in depositing the materials freely, 3D printing technique could construct more complicated structures at lower cost. In the past 4 years, the building and construction group at Singapore Centre for 3D Printing (SC3DP, NTU) has done a series of studies on concrete 3D printing. Presented in this paper are the overview of the current research at SC3DP focusing on 3D concrete printing with consideration in materials, machines and design. Conventional cementitious materials have been printed, including mixtures with supplementary cementitious materials (SCM), admixtures, recycled glass as aggregates, as well as geopolymer. Stainless steel cable and various types of fibres have also been incorporated to strengthen the cementitious mixtures. The interlayer bonding was studied and improved with novel nozzle design and a good balance between printing and pumping speed. Architecture design is further adapted considering the features of 3D printing technique, thus yielding some unique structures with optimized geometries.