From Realtà Mapei n° 28 - 7/23/2019
Converting a Cold War bunker to a high-tech wine cave
MAPEI’s alkali-free, liquid set accelerator for shotcrete was used to speed and strengthen the concrete application that turned a 1950s-era bunker into a luxurious, high-tech wine cavern.
In the world of natural gas, Tenneco has a long history. Around World War II, the company – then known as Tenneco Oil and Gas Co. – controlled the pipelines that deliver oil and gas along the Eastern Seaboard of the United States. By the 1950s, a series of acquisitions transformed Tenneco into an international force. With the advent of the Cold War, Tenneco was concerned about security and wanted a location for its company headquarters that could be easily controlled.
In 1956, Tenneco constructed a single facility from which the company could safely control its global gas lines. The site chosen for their new headquarters was in Hockley, Texas – a suburb 40 miles northwest of the facility’s previous location in Houston. At that site, Tenneco also constructed the Tennwood Golf Club, which served as a nearly 1,000-acre (405-hectare) resort for employees and their families.
After the Cuban Missile Crisis in 1962, the Cold War became an international concern. In an effort to protect its global headquarters and employees from a nuclear blast, Tenneco built a 12,900-square-foot (1 198-m2 ) underground nuclear bunker facility with concrete walls measuring 3 feet (0.91 m) in thickness.
The end of the Cold War and the rise of technology brought many changes to the oil and gas industry. A series of mergers resulted in the oil and gas giant becoming a major auto parts company that is now headquartered in Lake Forest, Illinois. The company’s former global headquarters in Hockley is now The Clubs at Houston Oaks – one of the most exclusive family resorts in an area known for exclusive resorts.
Sitting on the 1,000-acre (405-hectare) footprint of the Tenneco property, Houston Oaks features luxury homes and lodging, tennis courts, an equestrian center, a shooting range, a clubhouse, a chapel and a soon-to-be championship golf course that is currently under construction on the existing course. Even the underground bunker remains, but it has been transformed into a state-of-the-art, Napa Valley-style wine cellar known as Bunker 55o.
The wine cellar serves as a complement to the resort’s working farm and ranch, a greenhouse (which features an aquaponics farm) and a farm-to-table restaurant. The cellar is always kept at 55oF (13oC) with an ideal humidity of 70 percent. In the cellar, Houston Oaks’ wine club members have the option of reserving storage bunks that have space for 450 to 5,000 bottles of wine each. This massive wine cave also features a private dining room, a bar and event meeting spaces. One echo of Cold War spy drama remains amid all of this luxury: Entry to the cave requires a retina scan.
MAPEI PRODUCTS ON THE JOBSITE
Byer Builders, Inc. was charged with sourcing a team of professionals, plus the most suitable products, to transform Tenneco’s Bunker 55 into Houston Oaks’ high-tech Bunker 55o. At five days from start to finish, the project’s time frame was tight. With no time to waste, Byer Builders reached out to Bill Allen, Business Development Manager for Tunneling for MAPEI’s Underground Technology Team (UTT), to assist with the shotcrete chemistry and ensure that the project was completed to the highest standards. Allen was asked to perform quality control at the concrete truck to ensure that the proper concrete slump was maintained during shotcrete production; he also worked as a nozzleman during the installation. As an American Concrete Institute examiner for nozzleman certification, “I enjoyed having the opportunity to handle the nozzle on this job,” Allen said.
For his part, Byer Builders’ Dave Johnson was glad to have Allen’s experience on his jobsite. “I am excited to work with MAPEI UTT, and welcome the products and support they bring to our industry,” Johnson said. Allen observed, “It was apparent from the moment I arrived, all the attention to detail Byer gave to the installation and preparation of the embedded mechanical fixtures and steel lath that formed the cavern’s interior arches. Quality shotcrete is important, but the preparation is also as important.”
The shotcrete installation was hand-sprayed using MAPEI’s UTT product Mapequick AFK 888, an alkali-free, liquid set accelerator for shotcrete. “Utilizing Mapequick AFK 888 allows shotcrete to be sprayed in one pass, about 6" to 8" [15 to 20 cm] thick on the arches and overhead,” Allen said. “This is amazing because you are basically hanging concrete upside down without a form and defying gravity.” Concrete mixed with Mapequick AFK 888 adheres better to surfaces and has higher mechanical strength than concrete without the accelerator. This means no slumping or sagging of unrestrained concrete with high-early strength performance that satisfies tight construction schedules.
“The AFK 888 accelerator produces shotcrete that is characterized by rapid-setting times, yet allows easy trimming,” said Dominic Petrella of Petrella Concrete. “Dominic is a concrete artist; he skillfully carved the coves and arches that gave the cellar a great look,” Johnson said.
With more than 90 years of combined experience, the team of shotcrete applicators finished the project on time with superior performance, in part thanks to MAPEI technology and expertise.HOW MAPEQUICK AFK 888 SAVED THE CAVE
The transformation of Tenneco’s Bunker 55 into Houston Oaks’ highn that the installation had such a tight time frame, the contractor knew that the shotcrete had to rapidly set and cure, and that they could count on MAPEI’s technology to make this happen. Mapequick AFK 888, an alkali-free, inorganic salt-based liquid accelerator that is often used in tunneling projects, was added to the shotcrete to accelerate the curing process. In basic terms, Mapequick AFK 888 contains ingredients that activate the silicates contained in the concrete, causing a rapid curing reaction.
The fact that Mapequick AFK 888 is alkali-free means that the chance for alkali-based corrosion is reduced. Alkali is one of the most harmful substances in concrete – causing swelling, spalling, cracking and even premature structural failure.
Another bonus of using Mapequick AFK 888 is found in the improved bonding characteristics that the concrete gains from the additive. Shotcrete bonds better to rocky and/or uneven surfaces when it is used in conjunction with Mapequick AFK 888, resulting in less concrete rebound and cost. In addition, shotcrete mixed with Mapequick AFK 888 is 95% more compact than a sample of surface-compacted reference concrete without an accelerating agent. Moreover, on a project with a tight schedule, ease of application and finishing is crucial because time is money.
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