Printability Region for 3D Printable Engineered Cementitious Composites (2024-05)¶

The integration of reinforcement in 3D concrete printing (3DCP) presents a major challenge in current 3DCP industry. Engineered cementitious composites (ECC) with self-reinforcing characteristic provides a promising solution. However, the conflicting requirements between extrudability and buildability are amplified for 3D-printable ECC (3DP-ECC) due to the existence of a large-amount of fibers. This study investigates the printability region for 3DP-ECC based on standardized field-friendly workability test. The effects of superplasticizer (SP) dosage, hydroxypropyl methylcellulose (HPMC) dosage and fiber content on the workability and printability of 3DP-ECC at varying resting times were explored. The results of grey relational analysis (GRA) show that the workability can be regulated by SP dosage, HPMC dosage, fiber content and resting time. The workability test results in conjunction with the printability evaluation results were used to define the printable region. The suitable ranges of workability parameters including spread diameter, slump, and penetration depth for 3DP-ECC are 130–142.5 mm, 1–31 mm, and 7.5–22 mm, respectively. In addition, the hardened mechanical properties of 3DP-ECC with satisfactory printability were examined by tensile and compressive performance. This study proposes a simple but effective method for predicting the printability of 3DP-ECC and the findings provide guidance for researchers and engineers to easily develop printable ECC.