Failing Infrastructure: Repair It, Don’t Replace It
Over the last decade, there has been much discussion by political leaders around the need for repairing our nation’s infrastructure, including the costs involved and the challenges associated with approving legislation toward that effort. There are plenty of horror stories about how our roads, bridges, highways, overpasses, and airports are falling apart. Often overlooked, however, “out of sight, out of mind” is the vast array of underground infrastructure that is also failing.
While there are millions of underground structures of every size and description, such as vaults, manholes, elevator shafts, tunnels, and basements, the focus on this article is on vaults and manholes as they happen to protect our communications and power systems. Some are experiencing decay due to their being in place for decades and susceptible to highly acidic soils, groundwater, and seismic activity. Whatever conditions that may exist, ultimately the component of an underground structure that is vulnerable and thus the cause of decay is ironically a component required to be included in the structure for added integrity: Rebar. As moisture, from inside and/or outside the structure, penetrates the concrete, it is wicked into the rebar. This moisture combined with oxygen creates an environment that causes corrosion of the rebar, otherwise known as rust. As rebar rusts, it expands with pressures up to 36,000 psi. This force cracks the concrete and pushes it free from the walls and ceilings of whatever structure it was designed to support.
For reasons previously stated, there are countless vaults in service, throughout the United States, that are unsafe to enter, never mind work in. The vaults are also unsafe for the lines they are designed to protect. The communication lines within the vaults are damaged when large sections of concrete from the walls or ceilings give way and fall onto these lines, cutting out phone, fax, electrical, and internet systems to entire communities. This could also happen to electrical vaults that supply power to entire communities. There are additional hazards should a vault or manhole fail. Most of these vaults are under our streets and sidewalks. Imagine the chaos of one of these vaults collapsing on a street that serves as a major artery for supporting traffic. The traditional solution for such a failure is replacement – a costly and time-consuming undertaking. The potential for tragic consequences to not only public safety, but also to what a facility failure could have on commerce overall, makes it a challenging proposition for public works departments around the country when faced with the enormous cost and time involved with items that might go unseen for extended periods of time. But no more. There is now a solution that makes decision making much easier for public works professionals due to the significant savings in cost and time.
JES Supply Company was contacted by a local underground utility contractor, Terra Contracting, Inc., who performs maintenance and installation work for one of the largest electrical companies in the Western United States and was asked to participate in finding a solution to the problem of the decay in these types of vaults – one that allowed for the repair of the vaults rather than the costly and time-consuming undertaking of replacing them. The team at Terra believed that if they could identify the right product to incorporate with their expertise in installing vaults that they could offer a solution to their customer that would also translate into other applications within the community. They knew that they needed a material with the following characteristics: a quick cure rate, high strength, high adhesion, and non-toxic. It also needed to be safe and durable. JES Supply happened to have a product that contained those very components. It is called FLEXKIT.
JES and Terra’s combined efforts resulted in the development of a system for making lasting repairs of underground vaults but has applications for all types of underground structures. After a tremendous amount of research and development, the FLEXKIT Vault Repair System was born. FLEXKIT, JES’s premier concrete repair material, met and exceeded all the requirements needed for this highly sophisticated work. FLEXKIT is a thermal set vinyl polymer, which cures in as little as 15 minutes, making it a quick repair. FLEXKIT develops compression strengths as high as 12,000 psi. with bond strengths to concrete failure, making it strong and long-lasting. FLEXKIT is also, very importantly, waterproof. So too, the primer, JESPrime, when cured becomes waterproof. When applied to the existing or new rebar, it will encapsulate it and stop rusting in its tracks by placing a permanent barrier between the rebar and the oxygen and moisture responsible for corrosion. FLEXKIT contains zero VOCs.
While FLEXKIT is the material that makes the system possible, the entire system involves a standard procedural sequence of activities for a successful long-lasting repair that maintains a high regard for the workman’s safety. The interior of the vault is secured with timber and jacks. Once all the shoring is in place, the wires are wrapped with protective blankets and tarps to protect them from damage in the event “chunks” of concrete fall from the walls or ceiling. Small electric chipping hammers are used to remove the loose concrete. Shoring must be moved and relocated as the concrete removal progresses. All loose concrete must be removed from the walls, ceilings, and floor. All rebar that has deteriorated beyond use must be removed and replaced. The concrete and remaining rebar are cleaned and then conditioned with the JESPrime. This primer makes its way into the pores of the concrete and expands as it cures, creating an extremely strong watertight mechanical bond in addition to cutting off any further rusting. Forms are installed and the FLEXKIT is applied to the primed concrete. The FLEXKIT bonds on a molecular level with the primer assuring the strongest of bonds. Flex X is an accelerator and is added to the FLEXKIT mixture to quicken the curing process. The work area is tight. Low ceilings, multiple wires, and forced air ducts are all in the way. The access manhole is only 30” in diameter, adding to the difficulty of placing forms, all the while working with a harness and cable attached make the work challenging, requiring coordinated actions during the entire process. After the FLEXKIT material has cured (in as little as 15 minutes), forms are removed and touch-ups in tight corners are made. The vault is then finally cleaned and returned to service.
It may also be helpful to know that FLEXKIT was placed in an exhaustive two-year trial with another of the Nation’s leading electric supply companies servicing the Southwest United States. This is the only system that they will allow to be used inside of their vaults. A sample of the tests performed was compression strength, adhesion, and chemical irritation. FLEXKIT passed all with flying colors.
FLEXKIT is packaged in two forms. For small repairs, an actual kit with all items needed to make the repair is within the kit, or for large repairs a 5-gallon pail of the FLEXKIT material can be secured. Both sizes are packaged in 5-gallon metal pails with metal lids and cam locking rings. Metal pails are used for packaging for their puncture resistance and ability to help prevent spills and loss of materials due to rough handling practices of well-meaning, warehouse personnel. They stack neatly and can be carried with ease.
Author: Ed McSwain
Ed has been involved in the underground utilities industry for the past 41 years, 28 years as a General Contractor specializing in the installation of all underground systems throughout the Southwest United States. In the last 8 years, Mr. McSwain has ventured into the concrete coatings industry, supplying contractors with products used to repair and preserve concrete both above and below ground.