Denka CSA Case Studies

Wastewater Treatment Plant - North Shore
  • Location: North Shore, Auckland

  • Project Dates: 1994

Project Description

On two large concrete structures at the North Shore City sewage treatment plant, Denka CSA was specified to eliminate structural cracking and expansion joints. Downer Construction managed the application of the Denka CSA concrete, in conjunction with their consulting engineers Kingston Morrison Ltd.

One of the two structures was the 48m-diameter clarifier, which has a 200mm thick floor, sloping at 1:24 near the circumference and at 1:8 near the centre.
The second structure, an activated sludge reactor, has a 300mm thick slab measuring 45m x 37m.

Several aspects of the project required careful attention to ensure a satisfactory result. The ambient conditions involved warm weather with a moderate wind velocity and low humidity. It is essential that site concrete or base areas be wetted down before pours, due to the reduced availability of bleed water. This ensures that sufficient water is retained within the concrete to prevent deleterious effects arising from absorption and evaporation. A gravity stress was created above circumferential bars, located at 300mm centres in the clarifier. The surface was broom finished and a curing compound applied.

Atlas Ready Mix Concrete supplied approx. 1000m3 of 40MPa concrete for the contract, requiring 43 tonnes of Denka CSA.

Products Used

Project People

  • Construction Company: Downer Construction

  • Consulting Engineers: Kingston Morrison Ltd.

  • Concrete Suppliers: Atlas Ready Mix Concrete

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