11 May Pouring the foundation
Pouring the foundation is always the moment of truth. We have provided some helpful tips to make the process go smoothly and guarantee success. There are several methods available to place the concrete into the forms. Here are a few pros and cons to consider.
- Boom pump- The easiest way to place the concrete into the forms, but boom pumps create an extreme amount of additional pressure on the forms. The concrete is free falling some times from as high as 60′ in the air. This increases the chances of “blow outs” if you are not extremely careful. If you have no other method to place the concrete, ask the pump operator to use a smaller diameter hose at the end of the pump. In some locals you are allowed to use an “S” reducer where the steel pipe meets the rubber hose. Also, have the operator run the pump at a much slower pace. The issue is not with the Spider Ties but rather the strength of the plywood you are using. A rated form ply will perform much better.
- Grout or Line pumps- Also a very easy way to place concrete in the forms. Unlike a boom pump, these pumps are very gentle on the forms. A few thing to consider. These pumps use a smaller diameter hose for maneuverability. So the mix design of the concrete will require a smaller aggregate (rock) so that the concrete can flow through the line without complications. Check with the batch plant before ordering. Also do not drape the hose directly over the forms. The surge of the hose during the pumping process can cause the forms to be weakened. Grout or Line pumps are our first choice for concrete placement.
- Direct from the concrete truck- If your project site is organized properly many times you can save money by pouring the concrete into the forms directly from the truck. Be sure the ground is stable enough so the the truck does not cause cave-ins around your forms. Front end discharge trucks work the best for this approach.
Proper consolidation of the concrete is always recommended. The simple approach is to tap on the outside of the forms with a rubber mallet or hammer until the concrete is fully consolidated. Another more assured way is to use a concrete vibrator. One thing you must keep in mind when using a vibrator is that over vibrating the concrete will increase hydraulic pressure and can cause the plywood to “blow out”. So use caution when working with a concrete vibrator. Smaller vibrators always work best on walls allowing you more control.