By: Lynn Connors, GCP Applied Technologies
Skanska USA, the contractor hired to construct the $400 million Pensacola Bay Bridge, could earn a $15 million bonus for completing the work early. Likewise, when it contracted out the development of a collapsed section of I-85, the Georgia DOT offered a $3.1 million early completion bonus.
Fast-tracking bridge projects can be very lucrative for contractors, if the work is done right. There are numerous steps along the way where work can be accelerated. One of these is when waterproofing the bridge deck.
If you’re refurbishing a bridge, removal of original coating and waterproofing can be a time-consuming process. Talk with your waterproofing manufacturer to find out about the various removal methods, such as water blasting, that could minimize manual efforts. The removal method will depend on many factors, including the chemical composition of the original coatings and the type of waterproofing membrane now being applied.
Involving the manufacturer and applicator in pre-site inspections is important for new construction as well as refurbishment projects. For bridges that are being refurbished, the condition of the existing paving and waterproofing membrane will influence the refurb plan. For example, the amount of surface prep needed can vary, depending on the type and condition of materials used previously. In some cases, a single pass of a blast machine won’t be enough to clean the surface. If this prep isn’t done right, it can impact the bond between the bridge waterproofing and the substrate. It can be hard to know what situation you’re getting into without seeing these conditions firsthand, which is why pre-site visits are essential.
As the weather gets colder, ice crystals or condensation may accumulate on the bridge deck. This can result in work being halted when it’s too cold out. Nobody wants to have a crew waiting around to apply waterproofing until the weather changes. To extend your construction season and avoid work delays, choose a liquid waterproofing system that can be applied in moist, freezing temperatures.
Having the right QA methodologies gives contractors the peace of mind that they’ve performed a high-quality application. It is easy to validate the waterproofing membrane’s performance through adhesion testing that ensures the entire system is going to be fully bonded to the substrate. This way, as you apply subsequent coats of waterproofing, you know you have a chemical bond between the waterproofing layers and the substrate below. Wet film-thickness testing can also be performed immediately to verify the waterproofing was applied properly. This allows applicators to instantly identify and repair any areas in need.
In addition, certain waterproofing membranes have a color-coded system that enables applicators to confirm full-spray coverage at a glance. Overcoating can be performed at any time, offering greater flexibility and high-performance adhesion at day joints.
Having the flexibility to perform certain work, such as spraying on waterproofing, during overnight possession can accelerate project completion and minimize frustration for the commuters who rely on the bridge. This is a factor to consider when selecting your waterproofing membrane. Having the flexibility to apply waterproofing at night, in order to open the bridge to traffic in the morning and then apply asphalt paving the next night can result in both a reduction in traffic congestion and a significant time-cost savings.
Many waterproofing membrane manufacturers claim to have liquid membranes that are cold applied. However, some of these products must be heated up when used in the wintertime so they don’t become too thick. To avoid this extra step, and the extra cost of bringing generators to the site, it is best to choose a product that can be applied cold anytime of the year.
