Object: The Wilhelma water lily pool
Subtitle: In full bloom
Date: 06.03.14
City: Stuttgart, Germany 
Completion: 2013

Restoration of the water lily pool

Size: 650 m²
Products used:

PCI Nanocret FC, PCI Apogel F, PCI Repahaft, PCI Novoment Z3, PCI Bauharz, PCI Durapox NT, PCI Elastoprimer 110, PCI Escutan TF

Owner: Wilhelma – The Zoological and Botanical Gardens, Stuttgart
Company: Beton-Sanierungs-Technik GmbH, Waschek Betoning. (VDB), Filderstadt<br />Wamser GmbH, Wegebau und Außenanlagen<br /> Firma Estrich Bossert GmbH<br /><br />
Specialist advice: Erhard Kuttler
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The Stuttgart Wilhelma is unique in many respects. The only zoological and botanical garden in Germany has a long history that stretches back to the 19th century. In addition to more than 1,000 species of animal, the Wilhelma also houses around 7,000 plant species in its historical park and greenhouses. And some of them have found a very special place. Located in the centrepiece of the site, the Moorish Garden, is a 650-square-meter water lily pond. Since the beginning of 2013, the listed pool has been bathing in new splendour thanks to a complete restoration. The result is a spotless, heated pool for a noble blossom.

Review: After more than half a century, by the end of 2012, it was no longer possible to put off the restoration. Helmut Gekeler from the technical department of the Wilhelma called in the specialists who gave the large pool a makeover in the space of five months – including a break over the winter. Under the expert supervision of PCI Technical Specialist Erhard Kuttler and PCI Applications Engineer Peter Scharping, three regionally based building contractors worked on repairing the water lily pond. The plants had to be removed before the work could begin. This revealed a pool that was neither functional nor aesthetic. First of all, the concrete surfaces were cleaned with high pressure water jets of over 800 bar. After cleaning, the restoration experts coated the walls of the pool with a PCC putty, the PCI Nanocret FC fibre-reinforced concrete smoothing compound. This operation sealed the walls on the inside of the pond. The seal cracks in the floor area had to be sealed by impregnation using PCI Apogel F injection resin. Then a new smooth and faultless screed was laid. The construction professionals used the PCI Repahaft mortar bonding agent to bond the new screed permanently with the substrate. The installers laid the screed, manufactured from gravel sand and PCI Novoment Z3 fast setting screed cement, in the still damp bonding course to create a functional surface for the water lily pond. Before they could put the listed capstones back in their original positions, they had to re-profile the rim of the basin. This was done by mixing the PCI Bauharz epoxy binder with the correct grain size quartz sand. Last but not least – the grouting. For better adhesion of the joint sealing compound the restoration specialists worked with PCI Elastoprimer 110 wash primer. PCI Escutan TF was used to grout the spaces between the blocks of natural stone. Thanks to the tested materials from PCI Augsburg GmbH and the expertise of the contractors, the pool has turned out to be attractive and stable enough to meet the additional demands placed on it.