Structural glazing sealants supplied by a.b.e. Construction Chemicals were selected for the refurbishment of the towering atrium which is the focal point of Cavendish Square Shopping Centre in Claremont, Cape Town.

Dow Corning sealants – internationally regarded as the top quality standard for structural glazing – are imported from Belgium by a.b.e., which is the South African technical distributor for Dow Corning.

a.b.e. is part of the Chryso Southern Africa Group.

Glenn Bouwer, a.b.e.’s Branch & Sales Manager: General Construction in the Western Cape, says Dow Corning 895 one-part structural silicone adhesive, and Dow Corning 813C silicone weather sealant were specified for the refurbishment of the 20-year-old atrium, which reaches a height of 40 metres above the shopping centre’s main escalators on the ground floor.

“The old glass panels had started delaminating and the original sealants failed in places, resulting in leaks into the shopping complex,” Bouwer explained. “Cloud Nine Skylight Solutions removed the old glass panels and aluminium framing and fitted new powder-coated aluminium frames as well as high-performance NC 55E glass panels.

“The new glass panels weigh up to 200 kilograms each, and are made from 13.6mm thick toughened glass. The panels were fixed to the aluminium frame at angles of 30 degrees on the roof, and up to 80 degrees on the façade. This challenging installation clearly called for an exceptionally strong structural bond, which is why Dow Corning 895 was specified,” he adds.

Dow Corning 813C silicone sealant was subsequently applied as external weather seal on the atrium façade. In total, Dow Corning sealants were applied to about 800 linear metres of surface area.

Dow Corning 895 structural silicone is an odourless, neutral cure product, which exhibits excellent stability through a wide range of temperatures ( minus 50 degrees Celsius to 150 degrees Celsius). The cured product has exceptional weathering characteristics with a high resistance to ultra violet (UV) radiation as well as humidity. It can adhere to a wide range of substrates including powder coated aluminium; enamelled or reflective glasses; polyester coated aluminium profiles; and stainless steel profiles. All substrates are extensively tested for adhesion, staining etc by Dow Corning laboratories in Belgium prior to project start and, if successful, written approval is issued to the glazier.

Dow Corning 813C, which was used at the Cavendish Square refurbishment project as weatherproofing sealant, is a one-part, neutral curing, low modulus sealant suitable for interior and exterior applications, such as weather seals, expansion joints, and perimeter joints in buildings and other types of structures.

It has a joint movement capability of + 50%, -50% and provides strong, unprimed adhesion to various surfaces, including glazed surfaces, concrete, masonry, brick, wood, and some plastics.

Cape Town-based Cloud Nine Skylight Solutions has extensive experience in the application of Dow Corning sealants and is an approved DC applicator, currently in the process of finalising DC Quality Bond Membership, a stringent process that can take up to five years to achieve. “Dow Corning guarantees that Quality Bond members provide a level of workmanship and application that meets the company’s demanding requirements for safety and durability. Quality Bond applicators are audited annually to have their certification renewed,” Bouwer states.

Dow Corning structural glazing silicones hold European Technical Approval (ETA) through independent testing to European Technical Approval Guidelines (ETAG002).

Apart from many prestigious applications, a.b.e. recently supplied DC silicone sealants for Portside, which at 139 metres in height, is the tallest office block in the Cape Town; and also Alice Lane Phase 3 in Sandton; Protea Place office block also in Sandton; and the Bank of Mozambique in Maputo.