The Benefits of Mixing Properly
Choosing the Right Concrete Mix for Your Project
If you're like most contractors, you know having the right materials for your project often makes the difference between success and failure. One of the top questions is what type of mix you should use to get the best results. Unfortunately, as with many things in life, the answer is that it depends. Specifically, the amount of weight, expected use, direction of stress, and similar concerns will impact the type of concrete mix you use in your project. Fortunately, we've created this article for you to help determine the answers to these questions, making it much easier for you to decide what type of concrete you should use on your next project.
Choosing the Right Concrete Mix for Your Project
Let's get started by talking about the different factors that can impact your concrete mix:
Weight: Generally speaking, the more weight that a concrete pad will have to bear, the stronger or thicker it would need to be. As an example, this is why if you use 3,000 PSI concrete for both a 6" deep driveway and a 1" deep stepping stone, the stepping stone will possibly crack when it's driven over, while your driveway holds up for decades with no issues. When planning your project, consider how much weight it may end up bearing, and add depth or higher strength concrete if you're planning on having semi truck, larger RVs, and similar high-weight vehicles driving on it. Similarly, if you're looking for the best concrete for stepping stones and want to keep them relatively thin, step up to a higher-strength concrete to ensure it will bear up well against the extra weight, then use the Collomixer to make the process easy.
Weather and Climate: Your local climate and weather patterns may impact your concrete placement, especially at the time of pouring. In some very cold climates, it may make sense to place sheet foam below the concrete pad to reduce displacement from freezing. Another option would be to use air-entrained concrete to provide a place for the freezing pressure to go during cold weather. However, the biggest impact on concrete strength and setting speed will depend on temperature. In cold conditions, you may want to use hot water when mixing the concrete or have accelerants added, as this can speed up the curing process. You can also use heat blankets to keep the concrete warm, allowing it to set up properly during cold weather. In hot weather, conversely, you'll want to use retardants, such as fly ash, to reduce the speed that the concrete sets up so that you have time to work it before it hardens.
Torque: Sometimes the biggest issue for concrete isn't weight, but the torque it is placed under. The torque that is created by forces that pull laterally on the concrete can cause it to crack or fail prematurely. This applies regardless of whether you're looking for the best concrete for cement posts to tie off a radio or cell tower, or are adding a fence to your property.One common source is large privacy fences. Though you may consider the weight of the fence, it's also important to consider the strain of wind pushing on the fence, causing torque at the base. In these situations, using a longer post to reduce the torque on a shorter concrete base may be an option, as it spreads out the leverage of the wind against the fence by spreading it to the bottom of the hole. Having well-mixed concrete takes the right tools, however, and Collomix's range of available paddles make it easier to get the right mix for your project.
Environment: If your project is in an area that is boggy, has issues with erosion, or has a great deal of sand, you may want to consider taking additional steps to stabilize your concrete. Especially in freezing or wet conditions, it's very easy for the soil around your concrete to subside, causing problems with stability and its ability to bear weight. In these circumstances, you may want to make a thicker pad, add foam board beneath the pad, sink piles down to bedrock, or take similar actions to prevent the concrete from being impacted by these types of issues. Providing good drainage beneath the concrete may also help to reduce these issues, as it carries water away from problem soil, reducing its impact on them. You can learn more about the soil around the property by contacting your local university extension office with the property's legal location.
Curing Time: Unless you're using a fast-setting mix, using an accelerant, or adding hot water instead of cold to your mix, the full strength of the concrete mix will only be achieved after 28 days of curing in average temperatures.For example, a concrete mix with a strength of 3,500 PSI only has about 1,500 PSI ten days after pouring. If too high a load is placed on it at that point, it will fail, causing a lot of hard work to now require expensive repairs. If you do need your concrete to bear heavier loads or torque sooner than the expected time, pay the extra expense of having accelerants added to it. Alternatively use hot water and heating blankets to get it to cure faster and reach a higher strength sooner. If your project needs to cure quickly, requiring many small batches to be mixed, the Collomatic is easy to move while providing plenty of mixing power.
Now that we've looked at the basics of the factors that can impact your concrete pour, let's take a look at the best concrete mixes for different project types.
Best Concrete for Fence Post Foundations
When you're pouring concrete around fence posts, it's important to make sure that it has both the strength to hold up against higher torque loads, as well as the ability to set up quickly. This will allow you to finish the rest of your fence. For this reason, we'd recommend the best concrete for fence post foundations to include the use of accelerants in all but the hottest seasons, and adding hot water and heat blankets if the weather dips below freezing. This not only applies for the conditions during your pour but also the few weeks following it when concrete is expected to gain the most strength. For smaller projects, you can often find quick-setting concrete in bag mixes that will set within 20-40 minutes, though you'll still want to provide support braces on your fence posts until the concrete reaches its full strength. To determine how long the concrete will need reach your desired strength, chat with the engineer or test administrator at your local ready-mix plant or check the brand's website for the specific concrete mix. Either way, for most residential or agricultural fence posts, a concrete mix that will set up to 4,000-5,000 PSI will provide sufficient strength.
Best Concrete for Driveway Purposes
Driveways are different from fence post foundations because they bear weight instead of having to resisting torque. For this reason, many driveways, especially residential ones, use 3,500 PSI concrete. However, if your area has issues with soil stability or settling, adding reinforcement fibers or additional support into the pad can help prevent cracking, settling, or shifting with cold or wet weather. For a particularly pretty look in your driveway you may want to use a pea gravel mix. It is sprayed down with water once it initially sets up to remove surface concrete and allow the beauty of the pea gravel to show through. But what if you're expecting more weight than the average car or truck on a regular basis? In that situation, the best concrete will be a higher strength concrete, of 5,000 PSI to 10,000 PSI for frequent high-weight traffic such as loading docks with semi-trucks. Of course, in highly-industrialized applications, you'll want to speak to an engineer to determine the best concrete strength for your needs.
Best Concrete for Sidewalk Paths
When trying to find the best concrete for sidewalk use, it's important to remember some of the basics for stepping stones, which we'll talk about below. You'll want to pour a sidewalk pad that is a minimum of 2" thick. If you think it will have occasional driving traffic you should pour up to 3-4" and have a concrete strength of 3,500-5,000 PSI. Use the higher strength or fast-setting concrete for sidewalks that you want to see foot traffic on earlier in the curing process. You may want to go with concrete that has a smaller aggregate if you're using a thinner pad, as it will be easier to work in a thinner profile.
Best Concrete for Cement Posts
Cement posts do well in for a range of situations, but are most commonly used in foundation work, such as when a cement foundation must come above ground to prevent issues with settling or soil subsidence. In these situations, you'll often want a similar type of concrete to what you would use for fence post foundations you can continue construction relatively quickly. However, there are a few other aspects to consider when trying to find the best concrete for cement posts. You'll want to go with a concrete mix that has a compression point between 3,500 and 5,000 PSI. Some industrial mixes even go as high as 10,000 PSI, and are resistant to cracking and shrinking, allowing them to last for many years even if exposed to the elements, like balconies..
Best Concrete for Stepping Stones
If you're trying to find the best concrete for stepping stones, the best answer to your question is that it depends on your desired thickness. If you're making a stepping stone that is 2" thick or more, you can use virtually any concrete mix with a minimum strength of 3,000 PSI. For very thin stepping stones, that are 1" to 1.5" thick, you may want to also consider adding reinforcing fibers for additional strength. However, in most cases, if you keep your stepping stones about 2" thick, they should be strong enough to create a beautiful piece of yard art that will last for many years without issues.
By selecting the appropriate concrete for your project, you can ensure that your fence, driveway, stepping stones, footer posts, or sidewalks will last for many decades to come, providing reliable service and a wonderful appearance. However, the concrete is only as good as its mixing process, and Collomix's wide selection of mixing paddles and tools makes the process easy, so you can get your concrete mixed and get on with your project. Why not take a moment to see what we have available?
