Uniaxial compression on 3D-printed load-bearing walls with openings

Walls with openings, such as doors or windows, are a common feature in building construction. These openings, regardless of their size, are strategically positioned on each floor to fulfill ventilation or other functional needs. This study primarily aimed to investigate the structural performance of 3D-printed walls with door openings under uniaxial loads. The research focused on three types of walls with an opening: unreinforced, reversed U-bar-reinforced, and reversed U-bar with rebar-reinforced walls. All walls were measured 2000 mm in width, 1310 mm in height, and 120 mm in thickness, with an opening size of 1200 mm in width and 1000 mm in height. The study examined the load-vertical deflection behavior and cracking behavior of the tested walls. It was found that reinforcing the walls improved their stiffness and cracking behavior compared to the unreinforced wall. Moreover, it was observed that vertical cracks, along with small stepped diagonal cracks induced by horizontal stress, were prevalent in the tested walls. Both the reversed U-bar with rebar-reinforced and unreinforced 3D-printed walls with an opening exhibited brittle failure, characterized by significant spalling of the 3D-printed mortar layer surfaces on the column part near the opening edge corner. For the wall with only the reversed U-bar-reinforced, the test was stopped due to safety concerns before failure occurred. The reversed U-bar with the rebar-reinforced wall exhibited a lower ultimate load at failure than the unreinforced wall. This reduction in ultimate load is attributed to higher stress concentrations around the grouted regions within the reinforced wall which causes the earlier failures. Additionally, the failure of the reversed U-bar with the rebar-reinforced wall was observed at the location where the grouted core was incompletely filled.