Estimation of interface friction and concrete boundary layer for 3D printable concrete pumping

Abstract

3D concrete printing technology is a revolutionary method having multiple benefits over the conventional method of construction. Currently, the 3DCP process is in its initial stage hence required detailed investigation on many points. In the 3DCP process, pumping pressure plays the foremost role as the continuous, uniform and controlled flow of concrete is required to achieve desirable printability. To estimate the pumping pressure effectively, it is necessary to study the pumping parameters & interface friction. The interface friction at boundary layer is largely affected by the concrete composition. The estimation of pumping pressure for conventional concrete was found in past study in which the piston pump and metal pipe was used as a pumping assembly but no work has been found to estimate pumping pressure for 3D printable concrete using progressive cavity pump and high density polyethylene (HDPE) rubber hose pipe. In this study the interface friction between high density polyethylene (HDPE) rubber hose pipe and different 3D printable concrete mix was estimated by performing tribometer test. Effect of 3D printable concrete composition on thickness of boundary layer was also studied. From the experimental results, it was found that the interface friction is decreasing with the more workable concrete mix and the boundary layer (BL) was formed by the cement, water & smaller size of sand particles (<1.18 mm).