Evaluation and control of printability and rheological properties of 3D-printed rubberized concrete

The preparation of 3D-printed rubberized concrete (3DPRC) is crucial for achieving effective resource utilization of waste tires and improved performance of 3D-printed concrete (3DPC). This study presents a systematic investigation into the effects and mechanisms of different rubber aggregate (RA) on 3DPC printability and rheological properties, employing printing and rheological testing. Upon RA incorporation, 3DPC exhibited reduced extrudability and improved buildability, with a more pronounced effect observed at higher dosages and finer particle sizes. Water absorption in the surface cracks of RA increased the concrete's static and dynamic yield stresses, resulting in decreased extrudability and improved buildability. Notably, the heat treatment resulted in the partial closure of cracks on the RA surface, thereby reducing its water absorption rate and achieving a substantial increase in its extrudability, while maintaining buildability without compromise. As determined by flowability and green strength testing of 3DPRC, the suitable flowability range was 159-182 mm and green strength was 8.05-19.14 kPa, which corresponded to the rheological properties (dynamic yield stress: 637.53-899.81 Pa; static yield stress: 1299.55-1935.50 Pa). Overall, this study provides an important theoretical basis and experimental reference for designing and preparing 3DPRC, as well as for evaluating its printability.

Automated summary

This study systematically investigates the effects and mechanisms of different rubber aggregates on the printability and rheological properties of 3D-printed concrete. The incorporation of rubber aggregates reduces the extrudability while improving the buildability of the concrete. Heat treatment can decrease the water absorption rate of rubber aggregates and significantly enhance the extrudability. This study provides a theoretical basis and experimental reference for the design and preparation of 3D-printed rubberized concrete.