Often spoken of lightly, the small items that are used during a concrete slab installation are often the most important. From Abel Flex to Control Joints and beyond, it is imperative they are installed correctly to ensure a quality installation.
Abel Flex Expansion Foam
Abel Flex is used at cold joints (new concrete against another hard compound). It is placed vertically and is used to allow the concrete to shrink during the setting and curing phase without leaving a gap between the two hard structures. It also allows the new concrete to slightly move away from the other hard structure again without leaving a gap later on in it’s life, plus, allows the new concrete to move closer to the other hard surface without causing too much friction and making the new concrete “lift” up the face of the opposing structure.
Starter dowels are drilled into cold joint areas approximately 150mm into the adjoining hard surface. Then the new concrete is poured around the end sticking out. What this does is adhere the two hard surfaces together which stops the new concrete from either lifting or dropping as opposed to that other surface. This of course helps is strength overall, but also stop trip points from creating at that given area.
Re-Entry bars are typically made from N12 deformed bar or R-11 3/bar trench mesh. They are placed at the internal corners of your new concrete installation which is a high percentage crack area. They act as an extra reinforcement attempting to stop the early cracking and control it from these points.
Although not commonly used, trimming bars are installed around the perimeter of your new concrete slab attached to the slab mesh. They act for initial assistance in the setting tension of the concrete, which helps prevent and control cracking directly from the edges of the concrete.
Control joints can either be tooled into your concrete during the pouring phase, or can be saw cut into the surface after initial setting of the concrete. The length in between control joints is dictated by the thickness of the steel reinforcing that is being used, along with the installers general experience on where he/she predicts to be a high percentage crack point. They basically create a weaker spot in the concrete which is hoped that the concrete during tension will find it’s weaker spots to crack along, keeping said crack inside the control joint instead of being a dirty crack in the middle of nowhere.
There are also other minor things that are used during a concrete installation, but you’ll find these to be the most common and useful. When you receive your quotation, ask your contractor about these items. If they aren’t included in the pricing, then give us a call to quote your work and rest assured the installation is being done correctly.