Have you ever wondered what those black specks are in your concrete driveway? No, they’re not bugs—they’re bits of steel rebar used to reinforce the concrete while it was being poured. But over time, those tiny pieces of metal can rust and create ugly black stains. In this post, we’ll take a look at some of the most common concrete additives and their effects on the material’s lifespan. Stay tuned!
What Do Additives Do?
Before we get into the nitty-gritty of each additive, let’s first discuss what they actually do. Concrete additives are materials added to concrete mixtures to alter their properties and improve their overall performance. For example, some additives can increase the strength of the concrete, while others can make it more resistant to water or heat.
There are three main categories of concrete additives:
Admixtures – Chemicals added to the mix before or during the mixing process to change their properties.
Fibers – Small pieces of material (usually made from glass, steel, or synthetic materials) are added to the wet concrete mix to improve its strength and durability.
Reinforcement – Typically used in concrete that will be subject to high-stress levels, reinforcement is added to the mix to improve its strength and resistance to cracking.
While concrete is durable, it can be susceptible to cracking and chipping. The addition of concrete additives can help to improve the strength and durability of the material, making it less likely to crack or chip over time.
Common Types of Additives:
Water-reducing admixtures are chemical compounds that can be added to concrete to create the desired slump at a lower water-cement ratio than usual. Water-reducing admixtures are used to achieve specific concrete strength at reduced cement content. CO2 emissions and energy usage per volume of concrete produced decrease as cement content decreases.
Concrete properties are enhanced with this sort of admixture, and it helps concrete perform well in difficult situations. Water reducers have been employed chiefly on bridge decks, low-slump concrete overlays, and patching concrete.
Accelerating Concrete Admixtures:
These admixtures are used to shorten the time for concrete to set. It is helpful in cold weather or when a quick turnaround is necessary. These additives can also be beneficial when working with low-strength concrete mixes.
However, over-acceleration of concrete can lead to undesirable results such as reduced compressive strength and an increased risk of cracking.
Retarding Concrete Admixtures:
Slowing down the curing process may be desirable in hot weather, preventing cracking from drying too quickly. It can also keep fresh concrete workable for a more extended period so that finishers have more time to work with it.
But, if misused, retarding admixtures can cause significant delays in the set time and may require extra attention to ensure that the concrete does not set before it is supposed to.
These create tiny air bubbles within the concrete, which improves its freeze-thaw resistance and durability. It makes the material more resistant to deicing chemicals and gives it a longer life.
But, if too much air is entrained in the concrete, it can cause the material to be weaker and more susceptible to damage.
It’s important to remember that not all concrete additives are created equal. Some may boast about being able to increase the strength and durability of your concrete, but in reality, they’re just a waste of money.
If you’re interested in learning more about how ABC Asphalt, Inc. in Colorado Springs can help you with your next paving project.
Please get in touch today for a free estimate. We look forward to hearing from you!