Strategies For Managing Pressure On ICF Walls While Pouring
Pressure occurs at areas in the wall where you disrupt the flow of concrete such as short corners or large openings next to corners. It also occurs when you vibrate the walls between lifts to ensure proper consolidation. Vibration helps to get rid of air pockets and ensure there is no honeycombing in the wall. It also causes the concrete to return to a semi-liquid state, temporarily increasing the pressure in that area. In this video, we’ll show you how to combat pressure in these situations.
We’ll start with short corners. The wall is often weakened in this area due to there being a less than eight-inch offset between the courses. This makes these areas more prone to separating and pushing outwards during the pour. Because of this, you may need more than just vertical bracing. As you stack, make note of these spots where the offset is less than eight inches with a permanent marker, so you can come back later and brace these portions with horizontal strapping before you put on your vertical bracing and alignment system. We recommend strapping both sides of the wall. By doing this, you create a very strong and reinforced area. The horizontal strapping helps to spread out the pressure that is confined to a small area.
If you are building a multi-story structure, it may not be possible to brace the outside with strapping. In this instance, you would still place the interior strapping, but instead of the exterior wood strapping, we’ll make sure our horizontal rebar completely overlaps in this area. We’ll also zip tie it to the web every six inches. This is then repeated each course, maintaining the interior wood strapping and bracing and alignment system. This method eliminates the need for exterior wood strapping while still reinforcing the short corner.
The other area we are going to focus on is large openings next to corners. this is another confined space where concrete is unable to flow freely, causing a buildup of pressure for these areas. Again, we’re going to place exterior wood strapping around our corner and across the large opening. In this example, we placed it on the second, fourth, sixth, and eighth courses but the amount needed could vary from project to project. This will help spread and alleviate the pressure across the wall. The top course was included to keep the block from spreading because the bottom web and teeth had been removed over the opening. In this case, we would recommend strapping both sides of the top course.
The middle two courses are braced to keep the wall from pushing outward. This is the portion of the wall that we need to be the most careful with. The bottom of the wall is strapped as well also double check that it has been spot glued to the foundation. This will ensure that the pressure is sufficiently spread across the wall. When pouring, always start in the area that could be potentially troublesome and allow the concrete to flow away. Another strategy for pouring concrete around windows is starting with those areas and pouring concrete directly into the window cell opening. The area around them can then be vibrated for consolidation.
These are some of our recommended methods of combating pressure points in your build. Thanks for watching and please contact us if you have any further questions.