After seven years, the 55-kilometer bridge – 20 times the length of San Francisco’s Golden Gate Bridge – will soon be open for traffic.
“There was a lot of problem-solving required to protect the Hong Kong-Zhuhai-Macao Bridge from the surrounding elements and ensure its longevity,” Pearse said.
“It’s a complex international project with many stakeholders, as well as technical and operational challenges, but it was such a pleasure to play a part in helping shorten the travel time between the three cities.”
The HKZM Bridge, which will be among the world’s longest, is expected to cut travel times between Hong Kong and Zhuhai from three hours to just 30 minutes; further integrating the three cities in the Pearl River Delta and boosting the local economy.
Scheduled to open in the second quarter of 2018, the HKZM Bridge is one of the first major projects in China to combine a bridge with a sea-crossing tunnel. The bridge consists of three cable-stayed sections and one undersea tunnel that spans the Lingding Ocean, a busy local shipping channel.
High stakes
Constructing and waterproofing such a high-profile bridge is not without its challenges. 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 the ELIMINATOR bridge deck waterproofing system (previously Stirling Lloyd, now GCP); ICE & WATER SHIELD self-adhered roofing underlayment; PREPRUFE 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.
“Ultimately, the Authority chose GCP as a partner because we have a proven track record at both the consultancy and supply level. Our bridge deck waterproofing solutions have appeared on many projects in the region, including the Tsing Ma Bridge and Stonecutters Bridge,” Pearse said.
Waterproofing in high humidity areas can be challenging and time consuming since some solutions require extended time before each coat can bond. However, with the ELIMINATOR waterproofing membrane, it takes less than half an hour for each layer to cure.
“The ELIMINATOR product is very quick to install without the need for complex equipment and the unlimited open time helps reduce project time,” Pearse said.
“The ELIMINATOR 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.”
Instead of requiring expensive heater or spray machines, the ELIMINATOR solution is applied using equipment that is simple to operate and affordable to purchase or replace. On the HKZM Bridge two coats of ELIMINATOR 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 cold-spray-applied system is fast, effective and able to seal complex, critical details and penetrations with ease.
The ELIMINATOR system forms a tough, flexible and seamless membrane with no vulnerable joints, allowing it to perform throughout the design life of a structure and while simultaneously reducing maintenance costs. Its installation causes minimal disruption and it is capable of supporting traffic just an hour after application.
The system allows for wet film thickness gauge checks to ensure the specified film thickness is achieved across the area before curing.
“The ELIMINATOR bridge deck waterproofing range is protecting some of the world’s biggest bridges against corrosion and contributes to helping them achieve their predicted minimum design life of 120 years,” Pearse said.
“The system is designed to provide superior protection from water, chloride and frost, and has four decades track record of success both globally and in Hong Kong. To date, over 40 million m2 of ELIMINATOR waterproofing membrane has been applied globally, including in many areas of extreme climate.”
Bolstering against the elements
While the ELIMINATOR solution was selected for the deck, other parts of the bridge harnessed other GCP products. On the bridge’s boundary crossing facility in Hong Kong, for example, the Authority relied on ICE & WATER SHIELD self-adhered roofing underlayment to protect 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,” said Robert AuYeung, Asia Pacific marketing director-Hong Kong, GCP Applied Technologies.
“With ICE & WATER SHIELDunderlayments, the system’s nail seal-ability as well as dimensional stability provides excellent performance under high temperatures when applied under metal cladding.”
ICE & WATER SHIELD is a premier membrane composed of two waterproofing materials. First is an aggressive rubberised asphalt adhesive, and this is backed by a layer of slip-resistant, high-density, 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 rubberized asphalt to bond tightly to the roof deck. The Ripcord feature embedded in the adhesive provides the applicator a “split release on demand” feature.
On the tunnel running deep under the Lingding Ocean, the Authority selected PREPRUFE® pre-applied waterproofing membrane and BITUTHENE post-applied waterproofing. These were used to safeguard several tunnel passageways including at the Hong Kong boundary crossing facilities and staff subway section.
“Because both the PREPRUFE pre-applied membrane and BITUTHENE post-applied waterproofing are fast to apply, they helped the HKZM Bridge keep to its tight completion schedule while the ease of application of both products helped ensure any human errors were minimised during placement,” AuYeung said.
The PREPRUFE and BITUTHENE solutions can be used in several below-ground applications, including subway projects, to solve critical waterproofing issues. On top of this, both combine to block out water throughout construction of underground structures and tunnels.
On the concrete portion of the bridge, ADVA high-range water-reducing admixtures from GCP were used to enhance the concrete’s durability. In addition to providing excellent water reduction, ADVA admixture helps generate higher compressive strengths, better slump retention and improved rheology, which contributed to the high performance, underwater tremie concrete used in the bridge construction.
From the soon-to-open HKZM Bridge to the Queensferry Crossing in the UK, GCP’s advanced range of bridge deck waterproofing solutions not only protect some of the world’s largest bridges but also extend their lifespan. Pearse has worked on many of these bridge projects over his 20-year career. Reflecting on his most recent experience working on the HKZH Bridge, Pearse is almost nostalgic.
“Standing on the bridge, in the middle of the ocean with no traffic, while watching Macao glimmering and the Hong Kong airport in the distance, I feel so privileged to be part of a project that will hopefully boost the economy in the Pearl River Delta,” he said.