These products already contain polymers to aid bonding with portland cement and should never be used with a separate liquid bonding agent. Important: DO NOT USE products like Sakrete Top ‘N Bond and Sakrete Flo-Coat with a liquid bonding agent. Products like Sakrete Sand Mix and Sakrete Fast Set Cement Patcher will work well with a liquid chemical bonding agent such as Sakrete Bonder & Fortifier. Make sure to use concrete products that are compatible with a liquid bonding agent. Then mix up additional repair material to the proper consistency and apply over this thin scratch coat.Ĭhemical bonding: The chemical approach involves mixing up a liquid bonding agent that helps bond new concrete products to old. By the time you get the repair material mixed it will be ready. It is not necessary for this scratch coat to dry. Apply pressure to ensure that as much as possible is shoved into the nooks and crannies. Just think finger painting from kindergarten. Then, using a gloved hand or a rag, smear the material onto the area to be patched. You don’t need to measure the water-just turn the stuff into slop. Mix up a small amount of the repair material to a soupy consistency. This is simply a very wet coat made up by mixing the repair product with water. The most effective way to ensure a really good bond is with a scratch coat. Mechanical bonding: Let’s discuss the mechanical method first since it is really used in both approaches. There are two basic methods for bonding a portland cement based product to existing concrete: 1) mechanically and 2) chemically. You must mechanically remove these materials if you want the job to last. Paint, oil, glue from old flooring tiles are just a few. Note: Concrete simply will not bond to all substances. If the spots are too large or too deep for this to be practical, you may need a sealer to cover the stains before patching. Don’t forget the goggles (not just glasses) as this process will throw concrete all over the place. If the stains do not run too deep, you can chip away the concrete using a hammer and chisel. Simply washing the surface isn’t sufficient. Both of these will work their way down into the concrete. The two toughest areas to cover are those with oil and tree sap. Tough areas may require a pressure washer or mechanical abrasion. This can typically be done with a garden hose and a good nozzle. All loose sand, gravel, dirt, leaves etc. No matter which product you use, the process begins with good surface preparation. There are a variety of Sakrete concrete repair products available to fix concrete that has begun to deteriorate. Since this discussion is about best way to bond concrete, we will assume that your slab is good. The solution to all of these problems involves a jackhammer and several bags of Sakrete concrete mix. If it has multiple cracks that run so deep that they appear to run through the slab, a repair would only be temporary. If the slab has so much sand and gravel on the surface that despite sweeping and sweeping and squirting and squirting it just keeps coming back, don’t waste your time on repairs. If a sidewalk has either heaved or dropped at almost every joint, repairing it will not provide a long-term solution. Repair or replace? Determine if the concrete is structurally sound. When patching existing concrete, here’s how to achieve a strong and lasting bond between the new and old concrete. Portland cement concrete works well in mass and provides great compressive strength but not bond. There is nothing in basic portland cement that will act as a bonding agent. Fact: Fresh wet concrete does not normally bond well to existing dry concrete.ĭo you remember elementary school where one of the subjects on which you were graded was “plays well with others”? Concrete would have gotten an F.
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