Ziejewska Celina, Marczyk Joanna, Korniejenko Kinga, Bednarz Sebastian, Sroczyk Piotr, Łach Michał, Mikuła Janusz, Figiela Beata, Szechyńska-Hebda Magdalena, Hebda Marek
Faculty of Materials Engineering and Physics, Cracow University of Technology, Warszawska 24, 31-155 Kraków, Poland.
Plant Breeding and Acclimatization Institute-National Research Institute, Radzików, 05-870 Błonie, Poland.
Materials (Basel). 2022 Apr 12;15(8):2819. doi: 10.3390/ma15082819.
In recent years, 3D concrete printing technology has been developing dynamically. Intensive research is still being carried out on the composition of the materials dedicated to innovative 3D printing solutions. Here, for the first time, concrete-geopolymer hybrids produced with 3D printing technology and dedicated environmentally friendly building construction are presented. The concrete-geopolymer hybrids consisting of 95% concrete and 5% geopolymer based on fly ash or metakaolin were compared to standard concrete. Moreover, 3D printed samples were compared with the samples of the same composition but prepared by the conventional method of casting into molds. The phase composition, water leachability, compressive, and flexural strength in the parallel and perpendicular directions to the printing direction, and fire resistance followed by compressive strength were evaluated. Concrete-geopolymer hybrids were shown to contain a lower content of hazardous compounds in leaches than concrete samples. The concentration of toxic metals did not exceed the limit values indicated in the Council Decision 2003/33/EC; therefore, the materials were classified as environmentally neutral. The different forms of Si/Al in fly ash and metakaolin resulted in the various potentials for geopolymerization processes, and finally influenced the densification of the hybrids and the potential for immobilization of toxic elements. Although the compressive strength of concrete was approximately 40% higher for cast samples than for 3D printed ones, for the hybrids, the trend was the opposite. The addition of fly ash to concrete resulted in a 20% higher compressive strength compared to an analogous hybrid containing the addition of metakaolin. The compressive strength was 7-10% higher provided the samples were tested in the parallel direction to the -axis of the printout. The sample compressive strength of 24-43 MPa decreased to 8-19 MPa after the fire resistance tests as a result of moisture evaporation, weight loss, thermal deformation, and crack development. Importantly, the residual compressive strength of the hybrid samples was 1.5- to 2- fold higher than the concrete samples. Therefore, it can be concluded that the addition of geopolymer to the concrete improved the fire resistance of the samples.
近年来，3D混凝土打印技术一直在蓬勃发展。针对用于创新3D打印解决方案的材料成分，仍在进行深入研究。在此，首次展示了采用3D打印技术生产的混凝土-地质聚合物混合物以及专门的环保建筑结构。将由95%的混凝土和5%基于粉煤灰或偏高岭土的地质聚合物组成的混凝土-地质聚合物混合物与标准混凝土进行了比较。此外，还将3D打印样品与相同成分但通过传统铸模方法制备的样品进行了比较。评估了相组成、水浸出性、在与打印方向平行和垂直方向上的抗压强度和抗弯强度，以及耐火性和随后的抗压强度。结果表明，混凝土-地质聚合物混合物浸出液中有害化合物的含量低于混凝土样品。有毒金属的浓度未超过理事会第2003/33/EC号决定中规定的限值；因此，这些材料被归类为环境中性材料。粉煤灰和偏高岭土中不同形式的Si/Al导致了地质聚合过程的不同潜力，最终影响了混合物的致密化以及有毒元素的固定潜力。尽管浇筑样品的混凝土抗压强度比3D打印样品高约40%，但对于混合物来说，趋势则相反。与添加偏高岭土的类似混合物相比，向混凝土中添加粉煤灰可使抗压强度提高20%。如果样品在与打印轴平行的方向上进行测试，抗压强度会提高7-10%。由于水分蒸发、重量损失、热变形和裂缝发展，耐火性测试后样品的抗压强度从24-43MPa降至8-19MPa。重要的是，混合样品的残余抗压强度比混凝土样品高1.5至2倍。因此，可以得出结论，向混凝土中添加地质聚合物提高了样品的耐火性。
