Construction is a complex art, full of difficult and consequential choices
Occasionally, choices exist between similar products and items that perform equally under identical circumstances; therefore, price generally drives the decision. However, in practice, most discussions surrounding material choices revolve around trade-offs (e.g. ease-of-use vs. longevity, price vs. quality, etc.), and that is certainly the case with concrete vs. alternative products that are less durable or do not provide the demonstrated long-term service life of concrete.
Given complete control, an engineer would choose the best possible option available on the market, but cost pressures generally force compromise. One of the more challenging aspects of the job is determining where it makes sense to compromise and where you should stand firm. So, here are five reasons Reinforced Concrete Pipe (RCP) and Reinforced Concrete Box (RCB) Culvert is the gold standard and why you and your clients should advocate for RCP and RCB.
The Army Corp of Engineers estimates service life of RCP at 100 years, and that isn’t based on theoretical models. Humans have been using concrete for millennia, and its properties are established. In fact, you likely studied it in school.
One of the oldest recorded uses of RCP in the United States was in Mohawk, New York, in 1842. The American Concrete Pipe Association removed the portion shown below for archival purposes in 1986. The pipe at the time of removal was 144 years old, showing minimal wear, proving the 100+ year service life.
Using RCP, an engineer can confidently design, knowing that their project will still be there long after they are gone. More importantly, given the changing nature of our planet, RCP most often survives when disaster strikes. Concrete pipe does not burn, corrode prematurely, or float away when subjected to flood waters. In short, RCP and RCB have demonstrated durability and resilience during catastrophes and when combined with long service time concrete delivers time and cost savings.
A conduit in that fluid passes through it, and a structure to keep the conduit open under loading. RCP is the only product manufactured with both characteristics direct from the factory. Other products require the conduit’s supporting structure be built during the installation process. While theoretically sound, in practice, differences between local soils complicate design and reduce constructability. RCP arrives on a job site with the structure already built and ready to go. This results in the saving of time and resources and generates confidence that RCP and RCB will perform in some of the harshest conditions.
Including each step of the manufacturing process being monitored, tested, and recorded. When complete, to ensure all parameters and quality requirements are met, the product as specified by national standards are subjected to our 3-Edge Bearing Test (otherwise known as a D-Load Test) to confirm that products meet a standard greater than required.
The formal three-edge bearing test and how to calculate the D-Load are explained in ASTM Standard C497, Methods of Testing Concrete Pipe, Concrete Box Sections, Manhole Sections, or Tile. Wire reinforcement in concrete pipe adds significantly to its inherent strength. Reinforced concrete pipes have higher load capacities.
Ultimately, this means the product delivered to your job site is 100% proven to perform as promised. No surprises and each of our manufacturing plants follows strict quality control standards. Additionally, our products are produced domestically with no long hauls or overseas logistical challenges.
Face it, the underground is crowded and it is becoming more so. The space beneath a street in any urban environment is ground zero for all utilities, from power to gas to fiber optic conduit. Of course, these aren’t all installed at the same time, which means that no matter when storm drains are installed, you are almost guaranteed to dig near existing infrastructure. If you have chosen an alternative drainage pipe, this presents a problem. Alternative pipe materials rely on the surrounding soil for structure and laying new utilities nearby necessitates disturbing that soil envelope, causing potential compromise of the soil-pipe structure. This could, and likely will, cause deflection and collapse of the storm drainage system. RCP and RCB will withstand such treatment, making them the best options for future growth.
As RCP and RCB are less reliant on the surrounding soil for structure, installations can be designed giving contractors more flexibility to adapt to local conditions. This is, again, because the product delivered on the job site can bear the vast majority of the designed loading. No two job sites are the same. For some jobs, the soil conditions can change many times over the course of the installation. In situations where the structure is dependent on highly engineered, precisely compacted soils, this can complicate matters. This may mean that large quantities of high-quality backfill would need to be brought onto the job site. In addition to the expense, this could cause delays as these materials are not always immediately available. In some cases, these soils would need to be compacted to very high levels, which can be labor-intensive, and almost impossible to achieve in the field.
In the end, construction is complex enough. Why go looking for more trouble, delays, or increased costs? Concrete is the simplest to design, the least complicated to install and overall, the most durable. Make it your first choice and you won’t regret it later.