The joints in a concrete structure are the most vulnerable areas for leaking and cracking due to water penetrating them. In most structures, this leads to mold and fungus growth, and can affect the integrity of the structure. There are a variety of different waterstops available for construction joints, each with different strengths and weaknesses, which makes them appropriate for certain applications. Here’s some information on some of the most common.
PVC is used to waterproof construction joints by embedding it in both sides of the joint to create a physical barrier. A variety of widths, thicknesses, and sizes are available to suit almost any construction joint. The advantage of PVC waterstops is that they can be installed in virtually any conditions, including rainy and wet conditions. They also tend to last for a long time. The challenge comes in the actual install process. It takes time to correctly position the PVC to embed it in the joint, and during the concrete pour, it can easily become damaged.
Falling under the category of a hydrophilic waterstop system, bentonite is a swellable clay compound that expands up to 16-times when it contacts water. This helps it form a compression seal in concrete joints and fill small areas like cracks and voids in the concrete. However, as a hyrdophilic waterstop, this characteristic also means it’s extremely important to keep the bentonite dry and pour concrete immediately after it’s applied. If bentonite is prematurely exposed to moisture, it can damage joints, and weaken the concrete around the joint. There’s also a limited number of times the bentonite waterstop can expand and contract. Eventually, they wear out and have to be replaced. This makes them better suited for applications that aren’t often subjected to water and moisture, rather than extreme weather conditions.
Another hydrophilic compound, urethane also swells to form a compression seal in concrete joints when exposed to water. It grows to about 350-percent its original volume. Urethane waterstops can also be applied in strips or using a caulking gun, which makes them quicker to install. They also need to be kept dry prior to application, but need an additional 24 hours to cure before the concrete is poured. Throughout the curing process, the urethane needs to remain dry. And, like bentonite, urethane waterstops will eventually wear out after being exposed to water many times.
Typically made from copper, bronze, lead or steel, metallic waterstops are embedded similarly to PVC waterstops, however, because they are stronger, they’re used in specialized applications like dams or heavy construction projects and also in projects where materials will be exposed to extreme temperatures or chemicals.
At Maxwell Supply in Tulsa, we stock a variety of waterstops and accessories for your next concrete project. Stop by and see us or give us a call at 918-836-8606.