Coatzocoalcos Tunnel, Mexico
Mexico tunnel represents Latin America first for Stirling Lloyd's Integritank
With a highly successful track record protecting major immersed tube tunnels throughout Europe, Asia and the Middle East, Stirling Lloyd's Integritank spray applied high performance waterproofing system, designed to last the lifetime of the structure it is protecting, has now been used on the first such tunnel in Latin America.
The 1km immersed tube tunnel under the Rio Coatzacoalcos in the Mexican state of Veracruz, links the centre of the city of Coatzacoalcos, Mexico's major industrial port, with the Allende district on the east side of the river, home to several major petrochemical plants. It is part of an overall 2.2km long, four lane road construction project, designed to improve transport links across the river.
Constructed out of reinforced concrete, using pre-tensioned concrete caissons, the tunnel consists of six separate sections, five of them 138m long, and one 115m section, all 25m wide and 9.2m high. Pre-fabricated in a dry dock, they were then towed out to the immersion site and sunk into the river bed at a depth of 30m below sea level, before being connected.
Given the permanent immersion in aggressive salt water, and the challenge of producing a crack-free concrete structure, project design engineers TEC and general contractors, Constructura Tunel de Coatzacoalcos (CTC) were keen to trial a number of potential waterproofing solutions on site prior to commencement of the waterproofing of the actual tunnel itself.
State government of Veracruz, Coatzacoalcos City Hall, Banobras Finfra
Constructora Túnel Coatzacoalcos, Fomento de construcciones y contratas, Construcción Infraestructuras y filiales de México, Grupo OPC
Venture waterproofing construction (USA)
- Coatzacoalcos Tunnel, Mexico
Trial Part 1.
As a result, Stirling Lloyd's Integritank, together with various competitor products including several other spray-applied waterproofing systems, were all used on trial panels in a side by side performance comparison over a period of some two years.
The panels were rigorously tested under various exacting in-situ conditions including UV, high humidity and a broad range of temperatures, as the client, the engineer and the main contractor all carefully evaluated the performance of the respective waterproofing membranes.
Whereas some of the competitive products were seen to have pinhole defects develop over the trial period which could not be satisfactorily addressed, Integritank showed no such flaws and exhibited exemplary performance characteristics throughout. Tom Carter, Stirling Lloyd's vice president – sales, USA commented: "A product trial on this scale ahead of the actual project commencement is unusual, but we were happy to prove ourselves against the competition and confident that the technical performance of the Integritank system for this immersed tube tunnel application would be proven."
Trail Part 2.
Based on the company's advanced resin-based technology, Stirling Lloyd's Integritank is a high performance, fully bonded, two-coat system that is spray applied to tunnel surfaces where it cures rapidly to form a tough and seamless waterproofing membrane. Capable of being applied in a broad range of temperatures, the highly humid Mexican climate presented no problem for Integritank. However, it was the crack-bridging capabilities of the membrane, together with its cost-effectiveness - protecting the tunnel cost less than 1% of the overall project budget - that most interested the contractor and, ultimately, the client, the state of Veracruz.
Application Part 1.
Once specified for this project, Integritank was applied to over 28,000m² of the tunnel's external surface whilst in dry dock, to provide a watertight, chloride-resistant, flexible and protective barrier to water ingress. During application of Integritank's two contrasting colour coats, ongoing visual checking was supported by formal wet film thickness to confirm the correct thickness was being achieved. Once cured, holiday detection tests were conducted to confirm the waterproofing integrity of the membrane and, prior to permanent immersion, flood testing was carried out in the casting yard to test the buoyancy and water-tightness of the tunnel elements.
The final waterproofed section was successfully immersed under the river in March 2013, creating a new and strategically important transport link for the region's local oil refinery infrastructure.
Application Part 2.
Completion of this immersed tube tunnel project follows on from another major contract completed last year on the Buenos Aries Metro in Argentina, demonstrating the versatility of Stirling Lloyd in the global tunnel market.
That project involved another Stirling Lloyd sprayed waterproofing membrane, Integritank HF and a tunnel excavated using the New Austrian Tunnelling Method (NATM) as part of an extension to the Argentinian capital's mass transit system.
Tom Carter believes that Stirling Lloyd is now well positioned to continue its expansion across this region: "Projects such as the Coatzacoalcos and the Buenos Aries Metro tunnels continue to demonstrate that we have the technical resources, expertise and product reliability to work on large scale tunnel projects anywhere in the world. In terms of Latin America there are a number of other projects in design and production that we are currently involved in."