A 55-kilometre engineering feat

The new Hong Kong-Zhuhai-Macao Bridge has cut the travel time between the two Chinese territories from three hours to 30 minutes.

After seven years, the 55-kilometre bridge, which is 20 times the length of San Francisco’s Golden Gate Bridge and extends above the Pearl River Delta sandwiched between Hong Kong andHong Kong, is now open to traffic.

The Hong Kong-Zhuhai-Macao Bridge (HKZM) Bridge is one of the first major projects in China to combine a bridge with a sea-crossing tunnel, and consists of three cable-stayed sections and onethree cable-stayed sections that spans the Lingding Ocean, a busy local shipping channel.

Involved in the all-important corrosion-proofing of the structure was GCP Applied Technologies.

Its regional manager-Asia Pacific, Carl Pearse, says a great deal of problem-solving was required to protect the Hong Kong-Zhuhai-Macao Bridge from the surrounding elements and ensure its longevity.

“It’s a complex international project with many stakeholders, as well as technical and operational challenges.”

Waterproofing in high humidity areas is challenging and time-consuming since some solutions require extended time before each coat can bond.

Not only did the bridge deck waterproofing solution need to meet the strict construction and technical compliance of three government authorities (Mainland China, Hong Kong and Macau), complete stringent lab-testing, but the product also had to be available in large volumes and delivered within a tight deadline.

After investigating several solutions and many types of materials, the Hong Kong-Zhuhai-Macao Bridge Authority selected several waterproofing solutions from GCP Applied Technologies, including its Eliminator bridge deck waterproofing system; Ice and Water Shield self-adhered roofing underlayment; Prepruffe pre-applied waterproofing membrane; and Bituthene post-applied waterproofing. Adva concrete admixture from GCP was also used in the construction of the concrete portion of the bridge.

“Our bridge deck waterproofing solutions have appeared on many projects in the region, including the Tsing Ma Bridge and Stonecutters Bridge,” adds Pearse.

Waterproofing inWaterproofing areas is challenging and time-consuming since some solutions require extended time before each coat can bond. Pearse says the advantage of the Eliminator product, and Ator waterproofing membrane is that they take less than half an hour for each layer to cure.

“This product has been protecting high-profile bridges around the world in a wide range of challenging climatic conditions from extreme humidity and cold, to challenging marine environments for many years.

“Protecting some of the world’s biggest bridges against corrosion and contributing to helping them achieve their predicted minimum design life of 120 years.

“To date, over 40 million cubic metres of Eliminator waterproofing membrane has been applied globally, including in many areas of extreme climate.”

On the HKZM Bridge two coats of the waterproofing membrane were applied to three steel sections of the bridge. The first coat was a distinctive yellow followed by a second coat that is white.

The company’s Ice and Water Shield roofing underlayment protects the roof from the tropical rain that can sometimes turn torrential.

“Hong Kong summertime temperatures under metal cladding can reach above 60 degrees Celsius, which causes sagging of rubberized asphalt in some other protective products,” says Robert AuYeung, Asia Pacific marketing director–Hong Kong, GCP Applied Technologies.

This product is composed of two waterproofing materials. First, it is an aggressive rubberised asphalt adhesive, and this is backed by a layer of slip-resistant, highdensity, cross-laminated polyethylene film.

To protect the adhesive quality of the product, it is backed with a foldless release paper. During application, the release paper is easily removed, allowing the rubberised asphalt to bond tightly to the roof deck.

On the tunnel running deep under the Lingding Ocean, the Authority selected Preprufe waterproofing membrane and Bituthene post-applied waterproofing to safeguard several tunnel passageways, including at the Hong Kong boundary crossing facilities and staff subway section.

This article was first published in the September 2018 issue of Contractor magazine.

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