A significant growth in the size of wind turbines has led to the development of precast concrete wind towers that overcome limitations of the current technologies of steel towers. The precast concrete wind towers are frequently confronted with the complicated transport of long precast elements to the construction sites that are mostly difficult to reach. A new approach for the construction of concrete wind turbine towers out of hollow double wall elements is currently being developed at the Vienna University of Technology. The main idea is to combine the advantages of precast elements (e.g. no formwork needed) and in-situ concrete (e.g. better fatigue behaviour). The single and plane double wall elements, which can be easily transported to the construction site, are firstly connected to polygonal rings and then assembled into an elegant tapered tower. Once a ring segment is pre-assembled, it can be placed on top of the preceding segment enabling the tower to grow by e.g. 13m at a time. To create a monolithic structure the separate segments are then filled with in-situ concrete. This process of lifting one segment on top of the other and filling of the double wall elements with in-situ concrete is repeated until the final height of the tower is reached. The continuous filling of the segments with in-situ concrete allows the structure to rise without any joints in the core of the hollow elements, and thus providing a higher structural integrity and bearing capacity. In order to examine this new tower building technique in its feasibility and to show that this method allows economical, faster and more profound construction in comparison to the conventional construction methods the mockup tower segment has been designed, built and tested. The experiments and evaluation of the mock-up confirmed claims about the functionality and feasibility of the proposed construction method and revealed new technical challenges that have to be addressed for the construction of the following tower segments.