It’s easy to assume that concrete is the most impermeable or longest lasting ditch lining material. However, concrete isn’t quite as tough as many people assume when used in a thin layer for a purpose like lining a ditch. It’s particularly challenging to install on the vertical or steeply sloped sides of smaller ditches. If you’re still trying to decide between concrete and flexible liner options for your ditches, consider these common issues that make concrete and cement poor choices for the job.
Concrete is strongest against certain types of forces pressing directly down on the material. When the force comes from the side or causes the concrete to twist instead, the material is surprisingly weak and prone to cracking. Since ditches feature complex slopes and angles that eventually lead to different forces affecting the liner, concrete will eventually crack in practically every installation. Finding, and patching these cracks, can add hours of maintenance to every month of ditch ownership.
This popular building material is often overestimated in its impermeability and water holding capacity as well. Despite seeming like a smooth and impermeable surface, concrete is actually closer to a sponge in texture due to the formation of microscopic holes and tunnels. Cured concrete is porous enough to lose a surprising amount of water per year unless it’s lined with epoxy-based sealants or flexible liners. Why deal with a porous surface that constantly loses water when an impermeable flexible liner if available to solve the problem from the beginning.
Even for small irrigation and drainage ditches, soil testing is an important step to verify the ground can support the weight of the liner and water. Shifting soil leaves concrete without support, causing it to collapse suddenly and leak water into the soil below. The scouring effect continues to damage the rest of the ditch and potentially spread problems to surrounding properties and structures. Thorough soil testing still can’t predict every potential cause of instability, so using a more forgiving flexible liner is a better idea than choosing inflexible concrete.
Concrete is usually more expensive than flexible liners, especially once you add in the cost of installation, labor and transport. This is true for both pre-cast and poured in place concrete liners. Even if concrete is inexpensive and easy to obtain from a local supplier, it’s heavy and requires a lot of specialized labor. Pre-cast liner units are heavy and difficult to move in place. Once you consider the faster and easier installation process required for laying out flexible liners, you’ll definitely find the cost more affordable for your ditch lining projects.
Weight and Proper Handling
The high weight of pre-cast concrete liner sections also increases the chances of mistakes during installation. It’s harder for the installers to focus on getting a tight seal between the sections when it’s difficult for them to move and reposition the individual sections as needed. Liquid concrete is still heavy enough to interfere with the installation process, not to mention the delays needed for the concrete to cure and reach full strength. For a simpler installation, stick with flexible RPE liners instead.
If concrete is mandated by a local authority of some kind for your ditch lining plans, you can add a layer of flexible liner below for extra protection. This creates a secondary barrier to ensure that any leaks or water losses that occur won’t reach the soil below. If you’re handling high risk wastewater products, you can even use these layers of geomembrane to create a leak warning system that alerts you to problems with the concrete above. Don’t install concrete alone when you can use a flexible RPE product from BTL Liners as well.