Zurich, Switzerland

The Kaeng Krachan Elephant Park in Zurich Zoo is innovative in design and also in the way in which the elephants are looked after. The zoo’s growing elephant family now has more than six times as much room as they did before, including a number of different pools and showers both indoors and outside, which they make active use of. The centerpiece of the 11,000 m2 elephant park is the unique 6,800 m2 elephant house, an 80 m diameter facility with a multi-faceted timber roof structure weighing more than 1500 tons.

Project Requirements

Structural Foundations, Watertight Basements and Architectural Concrete Facades
Initially on site the main excavation required slope stability, with sprayed concrete sides and pile walls being necessary prior to the main construction works. For the structural foundations, including the prestressed ring beam, the highest specifications were set for the concrete with regards to strength development, self-compaction, low shrinkage and optimum installation within defined minimum time frames. The majority of the facilities utility services and plant rooms, together with some of the animal stalls, are built below, or partially below ground, which required them to be designed and built as watertight structures.

Structural Glazing
Elastic, movement accommodating, but airtight, bedding for the glazing was necessary to prevent stress and unwanted constraints on the glass panels. The engineers therefore checked materials for their suitability by carrying out compatibility and adhesive tensile strength tests.

Roof Waterproofing
The roof itself is unique, but a well proven and secure system was essential for the roof waterproofing, including around the 271 roof lights, each with a different shape. All of the necessary upstands, support platforms and approximately 1,500 corner sections had to be constructed by hand due to the variable angles for which standard profiles were not available.

Flooring, Containment Lining and Waterproofing
Mechanically and chemically resistant flooring that is also easy to clean and very durable was required in many areas. These high-tech and hygienic areas all demanded a top-quality finish for efficient running of the facility and for the good of the elephants.

Sika Solutions

Structural Foundations, Watertight Basements and Architectural Concrete Facades
All of the concrete for the specialist structural and watertight performance demands of the elephant house was produced using Sika ViscoCrete® admixture technology, including the ring beam to accommodate the roof loads and support the entire main building. The main excavation also required slope stability, with sprayed concrete sides and pile walls, once again Sika® ViscoCrete® admixtures were used, here in combination with and Sigunit® sprayed concrete accelerators for optimum performance and rapid completion of the sprayed concrete walls between the piles. The sprayed concrete was applied by the Sika® Sprinter mobile spray machine. The watertight areas and structures used Sika’s engineered waterproofing solutions to seal and accommodate the required movement capabilities in all of the joints, including the Sikadur®-Combiflex® system. Sika® Control technology was also used in the concrete to prevent shrinkage cracking in the floor slabs. SikaGrout® technology was used to fix and seal the roof supports into the structure.

Structural Glazing
As a result of the engineers testing of various materials proposed, Sikasil® structural glazing adhesives and sealants were used for structural bonding of the overhead glazing in adapted profiles, plus sealing and UV-resistant bonding of the insulated glazing for the edge seals.

Roof Waterproofing
The roof was produced and waterproofed with a Sika® Sarnafil® roofing system, fully bonded to the Duripanel boards, thus allowing joints in this substructure to be fully and securely bridged. The base of each platform support was enclosed in a maintenance-free Sarnafil® T fitting that was specially developed for the project by Sika.

Flooring, Containment Lining and Waterproofing
Fast-curing, sprayed Sikalastic® polyurea technology was selected as the ideal solution to waterproof and provide highly impact and chemically resistant linings on the exposed concrete surfaces. This system was used throughout the elephant house and for protection of the water retaining and holding tanks, including the waste-water containment and treatment facilities. Sikafloor ® resin systems were applied on all of the trafficked and exposed floors in the visitor entry and access corridors.

Products Used

Sika® ViscoCrete®
Sika® Control
Sika® Sarnafil®
Sarnafil® T

Project Participants

Zoo Zürich AG

Lead Architects
Markus Schietsch Architekten GmbH, Zurich

Sika Organization
Sika Switzerland