The effects of 3D printing on frost resistance of concrete

3DCP is becoming more common in the construction industry nowadays, however, the aspects of durability of printed concrete are not well-studied yet. This paper focuses on determining how frost-thaw cycles affect printed concrete samples, compared to cast samples of the same concrete mix and whether the conventional concrete frost resistance tests can be applied for 3D printed concrete samples. Two different concrete mixes were both printed and cast – first one was a ready-made mix provided by a dry concrete mix manufacturer and was used for reference, whereas the other mix was prepared at the lab. First, 7 and 28-day compressive and flexural strength as well as density were determined to establish the difference between mechanical and material properties of both printed and cast concrete samples that were intended to be used for frost resistance testing according to standard CEN 12390-9. Next, both printed and cast samples of both mixes were subject to a total of 56 freeze-thaw cycles while submerged in NaCl solution, allowing to determine mass loss of each sample after N frost cycles. To conclude, the obtained results enable the authors to evaluate how 3D printing affects concrete resistance to frost/thaw cycles compared to conventionally cast concrete as well as the possible causes for this. Further research is needed to improve both the design mix of concrete as well as the printing and testing methodology of frost resistance of 3D printed concrete which would possibly lead to its increased use in exposed outdoor structures in northern regions.