Concrete pipe has a long history of being a durable material for storm water, drainage, and sewer applications throughout the entire world. In Tacoma, some of the originally installed concrete sewer pipes are still in service today. This is because most concrete pipes should have a performance lifespan of 100 years or more.
Concrete pipe is what is known as a rigid pipe that provides both structure and conduit on site. Other types of pipe (such as PVC or HDPE) only provide a conduit and require careful backfilling to provide structure.
Concrete pipes, as a rigid pipe system, rely mostly on the strength of the pipe while only slightly relying on the strength of the soil surrounding it. The inherent strength of concrete pipes can compensate for site problems that were not planned for. This can include construction shortcomings, higher fill heights, and trench depths.
Concrete pipe is also less susceptible to damage during construction, as it will maintain its shape. This is because it will not deflect like other common pipe materials such as PVC or HDPE.
Some concrete pipes are reinforced by steel. Steel reinforcement in concrete pipes will significantly add to its inherent strength.
Concrete pipes may have a variety of different joint types. Here are three common ones:
ROLLING RUBBER RINGS
These start off round, and are usually stretched over the spigot then positioned in the spigot groove. As they roll up the spigot of the pipe, they become flattened to seal the joint. Through the use of these rings, the pipe sections can be assembled dry, and without the use of a jointing lubricant. In order for the ring to roll on, the pipe surface must be dry. If it is slightly wet, it must be dried out before using a rubber ring.
These rings can either be round or v-shaped. They are retained in a ring groove as the pipe slides into position. A lubricant must be applied on the surface of the ring in addition to the lead in surface of the receiving socket. The lubricant is provided by the pipe manufacturer and is a special solution often consisting of a soft soap mixture. Petroleum products (such as grease) should be avoided, as these can attack and corrode the rubber compound.
Also referred to as “EBs” or “Sand Bands,” these joints are used on a flush jointed pipe to prevent soil from entering the pipeline and eroding away the backfill. These bands are often adopted in sandy backfill conditions and are extended over the joint of flush jointed pipe.
As with all types of piping, sound installation practice is required to ensure that concrete pipes are able to operate at their fullest potential.