What Is Reinforced Concrete Pipe?
What Is Reinforced Concrete Pipe?
Reinforced concrete pipe (RCP) is a type of piping made from a composite material that includes concrete and a strengthening element such as steel bars.
This is done to increase the pipe’s tensile strength and ductility, which are properties that allow it to withstand stress without breaking or deforming.
RCP is often used in trenchless projects, which are construction methods that minimize the need for excavation, because of its durability and resistance to tensile stress.
It is also resistant to fire and weather and has a high compressive strength compared to other types of pipe.
RCP is commonly used in infrastructure projects such as storm sewer conduits because it can handle large volumes of water, such as during heavy rain or flooding, and safely divert it away from populated or industrial areas.
Additionally, RCP has a long lifespan of around 100 years, meaning that it does not need to be replaced frequently, which minimizes disruption to residents and road users.
Other materials that can be used to reinforce concrete include pre-stressed wires and strands, welded fabrics and mats, and various types of fibers.
To install a reinforced concrete pipe, you will generally need a minimum of two workers. Here are the steps to follow:
- Place the large pipe in the trench using a crane or backhoe, with the assistance of the workers.
- Insert the spigot end of the new pipe into the bell of the pipe that has already been installed.
- Use a crowbar or pipe pullers to install the new section of pipe onto the existing one.
- Once the new section is properly seated, use surveying or leveling instruments to ensure that the pipe is properly aligned.
Who Developed Reinforced Concrete Pipe?
Reinforced concrete pipe is a popular choice for trenchless construction because it is strong, resistant to fire and weather, and has a high compressive strength. It was first developed in the 19th century by Joseph Monier, François Coignet, and William B. Wilkinson, and is now commonly used for jacking operations.
In addition to steel, other materials such as pre-stressed wires and strands, welded fabrics and mats, and various fibers can be used to reinforce concrete pipe.
John M. Kurdziel of the American Concrete Pipe Association has referred to precast reinforced concrete pipe as the most commonly used pipe material for trenchless construction.
What Is The Minimum Cover For Reinforced Concrete Pipe?
The minimum distance from the surface to the top of a concrete pipe (RCP) under rigid pavement depends on the thickness of the pavement.
According to the AASHTO LRFD Bridge Design Specifications, the minimum cover for RCP in soil or flexible pavement is the greater of 1/8 the outside diameter of the pipe or 12 inches.
When there is a rigid pavement over the concrete pipe, the minimum cover is 9 inches from the bottom of the pavement.
This minimum cover requirement only applies to RCP designed in accordance with Section 12 of AASHTO. Special designs may allow for covers less than the minimum.
The minimum cover for plastic pipes is the greater of 1/8 the inside diameter of the pipe or 12 inches in unpaved areas.
In locations with pavement, the minimum cover is the greater of ½ the inside diameter or 24 inches.
For flexible pipes, the cover is measured from the bottom of flexible pavement and from the top of rigid pavement.
Rigid pipes, on the other hand, have most of the structure provided by the pipe itself, so the pavement does not have to be strong enough to spread the live load over the pipe in a shallow condition.
Rigid pipes can handle additional concentrated loads, unlike flexible pipes which rely on proper bedding and backfill for structural integrity.
When the pavement is rigid enough to spread the live load and develop a reaction with the stiffest element underneath it, the concrete pipe will act as a reaction point for the rigid pavement, which is why a minimum of 9 inches of soil cover is required between the top of the concrete pipe and the bottom of the rigid pavement.
How Is Concrete Pipe Underground Installed?
To safely backfill a concrete pipe underground, follow these steps:
- Place the backfill material on either side of the pipe, rather than bulldozing or dropping it directly into the trench.
- Avoid using boulders or other large, hard materials that could damage the pipe during compaction.
- Make sure the backfill material is free from roots or any other organic matter.
- After backfilling and compacting, fill the trench to the required grade as specified in the project specifications.
- Make sure the pipe is buried deep enough below the ground before driving any heavy construction equipment over it.
