Waterproofing Las Vegas
One would think that living in the desert would mean that waterproofing was not a major concern. In some towns this may be true, but, amid the bright lights of Las Vegas, waterproofing is a very important part of protecting concrete and the overall structural integrity of these oasis buildings.
“Even though Las Vegas is in the desert, we deal with a very high water table,” says Glen Williams, vice president of Technicoat Waterproofing of Las Vegas and Southern California. “Water and waterproofing are important elements of every project here in Vegas.”
Besides the high water table, another source of water is the thousands of planters, which give casinos an exotic atmosphere, and give homes and businesses relief from the heat. “The more vegetation that can be used in the landscaping and architecture of the buildings, the better it is for the city overall,” stated Ron Weller, a waterproofing consultant with Section 7 Marketing, and the local representative for Carlisle Coatings and Waterproofing. Weller's thirty-plus years of experience selling waterproofing systems in Las Vegas has included a number of high-end casinos. “The casinos are looking for an overall feel of water, plants, and riches. It's a repetitive theme in the overall design of most of the casinos to create space filled with water and foliage.”
This means that waterproofing the concrete is critical, especially in the numerous planters used throughout the casinos. “Many of the projects I work on use just about every kind of waterproofing there is,” says Weller. “For numerous below-grade applications throughout the city, we have used bentonite between the concrete and dirt. Bentonite is an excellent means of waterproofing against the water table. Keeping the water away from the concrete is critical to the long-term durability of the concrete, not to mention the problems from moisture build-up. To waterproof the vertical concrete surfaces, we recommend a strong sheet membrane in conjunction with drainage board. Most below-grade applications are completely encapsulated in waterproofing and drainage.”
Another noteworthy architectural feature in Las Vegas is the multitude of artificial lakes and pools. “We have used a combination of bentonite and liquid waterproofing membranes on several of the pools and lakes,” says Williams. “A typical application consists of concrete poured on the perimeter of each pool and then waterproofed using a spray- or roll-applied liquid waterproofing membrane. The bottoms of the pools are covered with bentonite. The pools and lakes need the highest quality of waterproofing.”
The hundreds of planters that circle and adorn Las Vegas's casinos and hotels hold every type of exotic foliage imaginable, including some very large trees. “A majority of the foliage is grown in concrete planters. Every planter needs a full waterproofing system that includes a drainage system. We recommend rolling a liquid membrane waterproofing system on all the planter walls. The bottom of the planters should then be covered by bentonite and drainage board, along with a combination root barrier protection board product,” Weller noted. “It's also critical that the drainage and root barrier systems cover the planters' vertical walls.”
Managing the movement of Water is the key. Properly installed drainage in combination with thorough waterproofing will allow the water to drain properly. “If you can control the movement of the water, you win the battle,” says Williams.
Lightweight penetration sleeves
The soon-to-be-completed Las Vegas hotel (formerly referred to as the La Reve Casino and featured on the cover of our January 2003 issue) has many water features that required piping to penetrate the concrete walls. “This hotel is going to have more water than Lake Mead,” says Mark Speros with Kerr Engineering, exaggerating only slightly, “so sealing around the pipes was critical.” Speros convinced mechanical contractor, Hanson Mechanical, to use a clever new device to create the penetrations: PSI's Century-Line Sleeves. Made of lightweight HDPE, with an integral waterstop, these sleeves install easily within the formwork. A 24x16-inch plastic sleeve weighs 22 pounds as opposed to a comparable steel sleeve at 150 pounds. With the plastic sleeve, a cap is nailed or glued to one inside face of the formwork, then the sleeve is fit into the cap. Cut just slightly longer than the width of the concrete wall, the sleeve is compressed between the two form panels. After the wall is poured and set, and the time has come to install the pipe, the caps are removed to reveal a perfect penetration. After the pipe was installed, Hanson used PSI Link Seal Modular Seals to seal the pipe into the opening to completely prevent water from leaking through around the pipe—even when under as much as 20 psi or 40 feet of head. This method has been so successful that it is being used everywhere pipes go through concrete, even around the drainpipes in the floors of the parking garage. And these sleeves are cheaper too—on this hotel job the hot dip galvanized sleeves originally specified would have cost 40% more. For more information on these sleeves and seals, go to www.linkseal.com.
The Las Vegas Monorail is the newest attraction on the famous Las Vegas skyline, linking major hotels and attractions. Gliding above traffic at speeds reaching 50 miles per hour, visitors can cover the 4-mile route from Sahara Station to the MGM Grand in about 14 minutes. With 27 stops along the way, there's something for everyone.
This is the most highly visible and costly public works project undertaken in Las Vegas in more than 50 years. Color and finish were major concerns for the engineering staff and the owners since the project would have an indefinite life span, with new sections and platforms to be added in the future.
As with any major construction project, cost was also a concern—not only the cost of installing a durable colored finish, but also the cost of maintaining the uniformity of the finish over time. Various types of high-performance precast and cast-in-place concrete were specified to meet the accelerated construction schedule. These components were cast at different times with up to a year between casting and installation. To further complicate matters, different precast facilities and different types of concrete construction were used, making integration and consistency even more difficult. While the Monorail itself is the property of the Las Vegas Monorail Corporation, the hotels and other private owners linked into the system are responsible for maintaining the individual loading platforms.
The Monorail is ultimately designed to extend to McCarran Airport and may eventually link to the Las Vegas-Los Angeles light rail connector. As more hotels and public loading platforms are added to the Monorail System, the color and finish must be flexible enough to yield consistent results when installed by various contractors over an extended period of time. Color fade, graffiti resistance, dirt release, and ease of maintenance were all evaluated during the specification process. The ongoing modifications that are expected throughout the lifespan of the structure make color consistency and finish uniformity key factors in the project's overall success.
Standard architectural finished grade concrete was considered during the original design phase, but was later rejected. While it provided the lowest cost option, the design team's color choices were limited to “gray or gray.” Integrally colored concrete was also a consideration. Although it offered a wider range of colors and the benefit of having color through the matrix of the concrete, it was eventually rejected due to cost as well as concerns over inconsistency between pours and between the various types of concrete construction. The general contractor for the project, Granite Construction of Watsonville, Calif., was also concerned that the integrally colored concrete originally specified would not meet the engineering requirements for strength.
Granite had recently completed a large bridge construction project for the Washington State DOT in which a masonry stain was specified. It outlined its success in integrating a similar mix of design considerations on that project to the engineering staff and owners of the Monorail project. After reviewing the available options and all o f these considerations, they specified a masonry stain manufactured by United Coatings as the best choice to ensure color consistency and finish uniformity over the life of the structure.
After 3 years of construction, the first phase of the project is nearing completion, with operational tests currently underway. The masonry stain has met all design criteria, and the color has remained consistent, allowing for easy touch up of repairs and modifications under the extreme ultraviolet exposure in the desert. When a new platform or station is added, the individual hotel or property owner is responsible for contracting the work. The stain has allowed these additions to be added to the system and maintain a consistent appearance. In areas that have been attacked by graffiti, maintenance personnel are able to remove the graffiti and recoat the affected area. Where graffiti has been a repeat problem, a clear, water-based, non-sacrificial coating is applied over the concrete stain.
The overall success of the Las Vegas Monorail project is the result of the integration of performance requirements specified by the engineering staff, input from the owners, and creative thinking by the general contractor. Working together, they identified the most important performance criteria for the concrete finish. Although the concrete/masonry stain resulted in a cost savings of approximately 20% over integrally colored concrete, the primary reason for choosing the stain was initial color consistency and the ability to reproduce the original color and finish on various kinds of concrete over many years.