Characterizing unrestrained drying shrinkage of 3-dimensional printed concrete

Approximately two decades ago, three-dimensional concrete printing (3DCP) developments started. Since the inception of this technology, it has developed rapidly because of the potential benefits it holds for the respective stakeholders. However, given the novel nature of this technology, several challenges must be addressed before it can be fully integrated into the construction industry. Due to the low volume of aggregates, resulting in high paste and fines content, and early exposure, 3DCP elements are prone to excessive shrinkage, which could lead to the cracking of 3DCP elements. This paper characterizes the unrestrained drying shrinkage of printed concrete in a laboratory with a controlled environment over 28 days. The tested mix exhibits a relatively high aggregate content in comparison to other printable mixes. Additionally, mechanical testing is conducted in the direction of printing at 7, 14 and 28 days. From the results obtained it is evident that this mix exhibits smaller unrestrained drying shrinkage compared to that of other printable mixes.