It is generally understood that the primary reasons for manhole rehabilitation are to stop inflow & infiltration, prevent hydrogen sulfide corrosion and restore structural integrity. At OBIC, we have talked extensively about inflow & infiltration as well as corrosion, but there seems to still be a lot of questions out there about how OBIC products help with structural issues. Two questions that we hear frequently are:
What’s the definition of structural?
What standard exists for manhole rehabilitation that defines structural?
This blog post helps to answer those questions, but our team is always ready to discuss your unique manhole rehabilitation projects and questions.
What standard exists for manhole rehabilitation that defines structural
It is important to begin by explaining that there are no ASTM standards, structural or otherwise, for manhole rehabilitation methods. Not willing to settle, we did some research to learn how various industry groups define structural lining.
One industry group defined structural lining as a liner that can withstand all exerted loads, including H-20 traffic loading by itself (standalone).
Another group determined that, as long as the standalone condition is achieved after complete curing, a liner could be considered structural.
Other industry groups suggested that a liner could be called structural so long as it adds to the strength of an existing manhole.
In the absence of ASTM, ASCE, or other engineering standards defining a structural liner, our judgment is that agreement between lining manufacturer, municipality and municipality’s engineer defines structural as applicable to a specific project.
OBIC 5000 as a structural lining system
OBIC 5000 is a structural lining system. A spray applied hybrid polyurethane, this lining system has a
Flexural strength of 10,500 psi
Tensile strength greater than 6,900 psi
Concrete has a flexural strength up to 700 psi and a similar number for tensile strength.
Clearly, OBIC 5000 is strong, but what really makes this lining system special is its hybrid characteristic. Polyurethane is well known for its hydrophobic reaction to moisture. In other words, it dislikes water. Competitive spray-applied polyurethane products require a completely dry substrate for successful adhesion.
Completely dry manholes are not impossible, but they are certainly rare and difficult to achieve. Hybrid OBIC 5000 is formulated with polymer ingredients that allow it to tenaciously adhere to the substrate, even when damp. What makes OBIC 5000 very desirable as a structural lining is that, unlike competitive products, it adheres to the substrate and provides its tremendous strength value to the host structure.
Manhole rehabilitation that stands the test of time
OBIC 5000, along with all OBIC products, are designed with a commitment to providing high quality, cost-effective water and wastewater rehabilitation solutions. Backed by our own team of chemists who employ rigorous testing to ensure consistency and quality, our products are customizable and designed to withstand even the harshest environments. Additional third-party testing has also proven that OBIC products are physically stronger than many other products on the market.