Three-dimensional concrete printing (3DCP) is becoming more common in the construction industry nowadays; however, the aspect of durability of printed concrete is not well-studied yet. Frost resistance is a very important factor for durability of concrete structures located in northern regions. Since air-entraining agents (AEAs) are widely used in conventional concrete, this paper focuses on exploring the potential of using AEAs in 3D concrete as well—the main objective is to determine how it affects fresh and hardened properties, including frost resistance of 3D concrete. Three different mixes were printed and cast—the dry mix consisted of ordinary Portland cement (OPC), limestone filler (LF), sand, as well as viscosity modifying agent (VMA) and superplasticizer (SP). Two mixes contained different amounts of AEA, the third one was used as reference. First, fresh state properties were tested—air content, density, and mini cone flow test. Second, 28-day compressive and flexural strength tests were carried out; bulk and particle densities were also determined. Next, both cast and printed concrete samples were subject to freeze–thaw cycles according to provisions of CEN/TS 12390-9, mass loss due to surface scaling was determined for each sample. As a result, printed concrete samples containing AEA in the amount of 0.06% of binder mass showed the highest frost resistance—addition of AEA decreased both flexural and compressive strength of this printed concrete mix by 30–40%. To conclude, the obtained results give an insight of how addition of AEA to printed concrete mix affects its properties both in long and short term. Further research of certain aspects, for instance, the air void system and pore distribution is needed to gain a deeper understanding on how to increase durability of 3D 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.

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