Quikrete, or fast-setting concrete, offers enormous convenience to the DIY enthusiast because it sets in under an hour and is easy to work with. It’s also indispensable in commercial settings where demand for use means waiting days for concrete to dry is not a viable option. So how long will finished poured Quikrete jobs last?
Quikrete is designed to last for decades and, if mixed and laid correctly, Quikrete will provide a strong, resilient material that is extremely durable. Because it sets faster and with less shrinkage than regular concrete, finished Quikrete structures can be even more long-lasting.
Like regular concrete, Quikrete needs to be fresh to work properly and is unlikely to be optimally effective if the dry mix is out of date.
In this article, we will explore what ingredients make up rapid-set concrete and how its shelf-life is affected by various factors. We’ll also consider the longevity of concrete and Quikrete and how long these structures can be expected to endure.
Concrete vs. Quikrete
Concrete, the most widely used man-made product worldwide, is made up of cement, fine and coarse aggregates, and water. The cement is key to the scientific properties of concrete because it is this that reacts with the water and causes hydration — the hardening and strengthening of the material.
The most commonly used cement for concrete is Portland cement, a fine powder that is usually made from limestone and clay or shale but may include other materials such as shells, chalk, slate, and iron ore. These ingredients are heated at extremely high temperatures and then ground into the powder that can be purchased as cement (source).
Concrete is unique in its ability to be molded while it is wet and then set like a rock once it has dried. This makes it the perfect material to build bridges, tunnels, and skyscrapers.
Quikrete, or rapid-set concrete, is made similarly to concrete, but it is formulated to hydrate much more rapidly. This is because of the addition of calcium sulfoaluminate (CSA), a compound that triggers a faster reaction between the minerals and water. This accelerated hygroscopic reaction — the absorbing of water — is what gives Quikrete its edge.
Uses of CSA Concrete
Calcium sulfoaluminate or CSA was discovered in the late 1950s by American Alexander Klein at the University of California, who developed a type of cement using CSA. This has been significantly enhanced over time, with significant development being done in China (source).
Regular concrete shrinks as it dries, and this can result in cracking. Because CSA concrete sets so quickly, it is less inclined to cracking, and this gives greater longevity to structures made with it.
It gains strength very quickly, allowing it to be used on structures that require quick-drying, such as bridges, tunnels, runways, and roads. Over time, it has proven to be even stronger than Portland cement and has a lower carbon footprint because of less carbon dioxide emissions during manufacture.
Quikrete is also useful for the home DIY enthusiast. It is easy to mix, and, provided you can work with it quickly enough, it is easy to lay. It will set in less than an hour as opposed to the days required for regular concrete to set.
How Long Do Bags of Quikrete Last?
Bagged concrete or Quikrete can be kept for anything from three months to a year, depending on how it is stored and what it is going to be used for. The reason for this shelf life is that the cement component of concrete is a compound that will trigger a chemical reaction if it is exposed to moisture of any kind. You can read more about this in “Does Concrete Have a Shelf Life?”
It’s important to test the moisture content if it is to be used for construction, as this needs to be under 5%. The strength of the finished product also deteriorates over time, and construction concrete is generally never older than three months. It is estimated that concrete loses 20% of its strength after 3 months and up to 40% after a year (source).
For home DIY projects, this is probably less important, and properly stored bags can still be used for up to a year, depending on what they’re used for. Older Quikrete can be used, provided the material is still loose and especially if it is being used for projects such as setting gate posts or mailboxes.
Storing Quikrete Bags
Incorrect storage is the number one reason why bags of Quikrete or concrete mix don’t last as long as they should. They need to be stored above ground level in specially designed sheds that are entirely waterproof.
They should be stored on platforms with fewer than 10 bags in a stack and only stored together with the same type of concrete. Their period of storage should be noted, and they should be removed in the order they were packed so that the oldest bags are removed first.
How Long Does Mixed Quikrete Last?
Once mixed, Quikrete needs to be worked with quickly. First, it’s important to ensure it’s properly mixed and that the correct amount of water has been added because too much or too little water will affect the strength of the finished product. Quikrete generally requires one part water to every five parts of the Quikrete mix.
Quikrete will start to set in 20 to 40 minutes, so it’s important to work quickly while the concrete is still malleable. However, this can be affected by outside temperatures.
If it is cold outside, below 32°F, then it may be better to delay the project unless it is critical. Quikrete will set slower in colder weather, and the risk of it freezing before it has set means that it could crack. One solution for this is to mix your Quikrete using hot water, and another is to set up a tent over the completed project with a space heater inside.
If it is very hot, above 90°F, and especially if it is windy or in direct sun, then you also need to be aware. Your concrete may set unevenly, as the top layer will set faster than the bottom layer. To avoid this, you can mix your Quikrete with very cold water — or even add ice!
The Durability of Finished Concrete & Quikrete
Concrete has earned its popularity because it is incredibly durable and can last for significant periods of time without deteriorating. Concrete is designed to resist weather, chemicals, and wearing, and its durability will depend on the type of concrete used as well as the environment it services.
For the most part, concrete or Quikrete structures are expected to last 50 to 100 years. Many are demolished ahead of this time frame because their function requires adapting rather than because the structure is no longer usable.
Concrete is able to withstand many factors that are hazardous to other substances. All of these augment its durability and are discussed below.
Humidity & Rain
Because there is no organic content in concrete, it is resistant to rot or rust, and moisture can only enter a structure through gaps or joints in the concrete.
Concrete is indelible and, therefore, cannot be impacted by insects or vermin. Because it is so hard, it is also impenetrable to them.
Freezing & Thawing
If properly mixed and laid, concrete is resistant to these most destructive weather conditions. Correct mixing will introduce air bubbles that allow for any moisture to expand into ice while the concrete is still wet.
Concrete resists corrosion from most chemicals, which is evidenced in its use in wastewater plants. An exception is acids, which do have the ability to dissolve the cement paste.
Concrete has been successfully used in seawater environments and, provided it is correctly mixed, is able to withstand seawater. Concrete that is low in permeability is necessary for these environments, and this is where quick-setting concrete is especially advantageous.
Concrete generally copes well in the presence of abrasion caused by weather, even when faced with fast-flowing water or ice. It can even withstand metal on tires, provided the correct strength of concrete is used.
For extreme abrasive environments, concrete strength should exceed 12,000 pounds per square inch (psi). For more on the relative strength of concrete and Quickrete, read “Is Quikrete as Strong as Concrete?”
Quikrete is an ingenious product that has many diverse uses. Its quick-setting nature makes it indispensable for many projects and a useful tool for the home DIY enthusiast who wants to do concrete projects without the expense of hiring contractors.
What’s critical about Quikrete, and similarly about all concrete products, is that it needs to be stored correctly if it is going to last as long as possible on the shelf. Once mixed, Quikrete must be used immediately to ensure it doesn’t harden before the job is completed. After that, your Quikrete project should be strong and resilient and able to stand the test of time.
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