Seaside resort Kaltern
Concrete technology, development of a self-compacting concrete, supervision - Lake Kaltern, South Tyrol
Project Description
The new building of the open air swimming pool on the coast of Lake Caldaro in South Tyrol has been constructed as a multifunction structure including a theatrical stage. The structure consists of strong jointed supporting cores and an elevated platform, which holds the swimming pool. Due to the complexity of the design, the entire structure was executed without expansion joints.
Task
We were commissioned from the town of Caldaro to implement
the high planning specifications of the architects (uniform, as defect free as possible surfaces, no formwork ties, no construction joints, design of tapering, non-broken edges, counter formed surfaces, very close reinforcement configuration, impossibility of the use of internal vibrating machines) on the building site and to plan and control the necessary measures for this.
Procedure
The realization of the architectural guidelines for the complex component geometry was only possible through the use of self compacting concrete. With the aggregates available on-site (crushed sand, gravel) and a special cement for self compacting concrete, a special self compacting concrete was developed.
First test mixes of the concrete supplier produced a sedimentation resistance and robustness of the concrete that was too low. For this reason, the mortar was optimized according to the recommendations of Okamura. The laboratory tests were conducted at the Technical University of Munich, MPA, Department of Building Materials. With the improved mortar, the final composition of the mixture was then tested and optimized in the laboratory of the concrete supplier.
For the desired quality of the exposed concrete surfaces, the method of mixing and, in particular, the incorporation of the plasticizer was crucial. The course of flow lenght for the deaeration of the concrete had to be extended compared to the length for average self compacting concrete.
For the success of the structure, a detailed elaborate and consistently implemented quality assurance plan was crucial, which was planned for every concrete supplier in both tests in the concrete plant and on site.
