The Right Mix

 CHOOSING THE RIGHT 01There are ways to choose the right concrete product.   

By Mike Boenisch

When it comes to home improvement projects, it is important to make sure that you, as the contractor, are using the correct material to ensure that not only you are happy with your work but that the clients are happy with the final product. Due to its economic benefits, concrete has become an extremely common product used in both residential and commercial projects. It also offers a lot of benefits for clients and contractors alike – it is long-lasting, requires little maintenance and is extremely durable. 

When choosing concrete for a project, contractors need to first determine what performance specifications need to be met such as strength, abrasion or freeze thaw. Premixed concretes are engineered and designed for a variety of performance criteria that can be used for many different projects, both for interior or exterior applications. However, not all of these concrete mixes will work for all projects. It is important for contractors to read the product’s technical performance information to help understand the difference between these mixes and which concrete product will give you the best result for your project. 

Not all Concrete Mixes are The Same 

Not all concrete mixes will yield the same results. When determining which concrete mix to use for your project, there are a few things contractors should consider. First, they should consider the type of project they are handling and how strong the concrete for that project needs to be. Concrete varies in strength that is measured by PSI, or pounds per square inch. For example, the average residential project requires anywhere from 2,500 PSI to 5,000 PSI. Contractors can also use lower strength concrete mixes for projects where points loads are not an issue, such as sidewalks or patios. 

For projects like concrete driveways, contractors will need a high strength concrete mix that will be able to withstand higher point loads and have good abrasion resistance where vehicle or equipment use is expected. Make sure to look into the local building codes requirements when choosing a concrete mix – certain codes may have specific technical performance requirements that need to be met. Many inspectors will require that the concrete mix technical performance specifications are displayed for them to review during the inspection.  

Second, contractors should be aware of the weather patterns in their area. If concrete is going to be exposed to extremely low temperatures, resulting in freeze thaws conditions, contractors should use an air-entrained concrete mix. The primary benefit of entrained air in hardened concrete is the resistance it offers to freeze-thaw damage and scaling caused by de-icing salts or chemicals. Most concrete contains some moisture which expands during freezing temperatures. Without room for this expansion, large forces develop that can rupture the surface causing what is commonly called surface scaling. The small, entrained air bubbles serve as reservoirs or expansion chambers to relieve these pressures. 

The third thing to consider when choosing concrete mix is whether or not your project will require finishing touches, such as staining or stamping. This may require a higher level of Portland Cement or fines to assure you can obtain the aesthetic finish you desire. 

Which Mix is Right for Your Project?

If you are working on a sidewalk or patio, one of the first things to think about or ask the homeowner about is how trafficked the area will be. For sidewalks, a concrete mix with lower PSI can be used due to the small amount of traffic that this area will see. For driveways that will be exposed to higher intensity equipment such as tractors, contractors should use a high-strength concrete mix. When working on projects such as driveways and sidewalks, it is important to clients that they maintain their look for a long time, so contractors should consider using crack resistant concrete mix. These mixes are high strength and are specifically formulated to reduce the risk of surface shrinkage cracks. 

On the residential side, modern and sleek styles have returned as a popular aesthetic, making way for concrete countertops as a popular trend. Choosing a concrete mix for your countertop is similar to choosing any material for a countertop. Homeowners want a material that is durable, safe, aesthetically pleasing and long-lasting. To ensure that the countertop can handle the wear and tear of a kitchen and is safe as a food preparation surface, the concrete mix should be high strength and be sealed with an NSF approved sealer.

For projects like setting fences or mailbox posts, strength of the concrete mix is not the only thing that contractors will think about. Projects like these usually require a quick set time so that clients are not impacted by the time it takes to complete the project. Fast setting concrete mix is ideal for projects that necessitate a rapid set for same-day use. Some fast setting concrete mixes do not require mixing or bracing, making the process even faster. 

Certain projects will require a very specific type of concrete mix. Fireplaces or firepits require a specific mix to be used in the fire box or areas needed to withstand high heat. 

With large scale projects like block walls, where reinforcement is needed to meet the high compression strength requirements for the project, contractors may need to core fill the blocks using a core fill grout. For smaller projects, there is an option of dry stacking your blocks without the use of mortar. Surface bonding cement mix allows for contractors to build a dry stack block wall without using mortar between each block, which can save time and money. These mixes are very high strength and can be used above or below grade and also allow for paint or stain to be applied after it has cured.  

When it comes to choosing the correct concrete for a project, there are so many performance needs to consider and a variety of mixes on the market. Contractors need to consider a number of variables such as strength and performance requirements, building codes specifications, temperatures during application and potential harsh weather conditions. Using the wrong mix can be detrimental to your project. However, the beauty of using concrete is, if the project is done right, it should last a very long time. 

Mike Boenisch is manager of Technical Services for Sakrete of North America at Oldcastle APG.

 

 

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