What is Utility Vaults?
Utility Vaults subterranean public utility equipment such as valves for water or natural gas or switchgear for electrical or telecommunications equipment. There are hundreds of thousands of man-accessible vaults in North America, with potentially tens of thousands of utility worker entries into those vaults each year. Large Utilities like Southern California Edison estimate at least 60% of vaults in the ground need repair.
Problems of Underground Utility Vaults
The most critical factor in vault maintenance is keeping water out. However, because vaults are underground, water tends to work its way down into them, making them an end point for leaks. Leaking vaults require pumping, create access problems and safety related issues for utility workers. Water also corrodes the structural steel supports, their concrete encasement along with brick retaining walls. Water also compromises the functioning of the mechanical equipment inside the vault. After several years of slow but steady water infiltration, a vault’s structural integrity will eventually be compromised, posing a danger to the equipment below and people above.
Coating Utility Vaults with Zebron
For the last 40 years, Zebron has been lining the inside of utility vaults (or coating the outside) with a seamless, impermeable, polyurethane membranes. Zebron coatings are spray applied, to any thickness, in a single application. The product cures to form a tough, highly impermeable membrane with excellent chemical resistance and durable physical properties. They are dry to the touch in 25 minutes and can be put into service rapidly. The coatings are locally manufactured in California, are USDA Bio-Based and NSF61 compliant for potable water.
Taylor Woodrow Research Laboratories evaluated Zebron coatings in their 1982 report No.014H/82/2372 “US Zebron – Likely Long-term od Coating Reinforced Concrete in Middle East Conditions.” Properties evaluated were:
- Chlorine diffusivity
- Oxygen diffusivity
- Water permeability
- Accelerated weathering
a) In the test procedure described Zebron coating of concrete reduces the rate of transmission of chloride to 1.8% of the value for an uncoated concrete sample (uncoated 4750 mg/m2/day, coated 86 mg/m2/day).
b) The use of Zebron reduces the oxygen permeability of uncoated concrete substantially.
c) Concrete coated with Zebron is impermeable to liquid water under the test conditions described (50 days at 100 KN/m2 differential pressure).
d) In the test described, Zebron can span cracks up to 1.4mm.
e) The adhesion, measured by pull-off, of Zebron to grit blasted concrete is high (2.40 N/mm2).
f)After artificial weathering the material darkens in color, no pinholing, blistering or chalking was evident after 2000 hours duration.