Concrete is a ubiquitous part of the modern world and can be found virtually everywhere you go. While it can be easy to assume that all of this concrete has exactly the same structure and makeup, actually, a surprising degree of variation exists. By changing the proportions, additives, or manufacturing methods, contractors can create concrete blends for highly specific needs.
One of the most interesting forms of concrete goes by the name of air-entrained concrete. More and more contractors are turning to air-entrained concrete to complete their building and paving jobs. If you would like to learn more about the basis for this growing popularity, keep reading. This article will outline three key benefits of air-entrained concrete.
Contractors commonly evaluate concrete in terms of workability. This term identifies how easily the concrete can be poured, leveled, and compacted — in short, how easy it is to work with. Traditionally, to create a mix with better workability, contractors would have to add more water.
Unfortunately, as concrete's water level increases, its strength rapidly drops off. Therefore, those in the concrete industry have long been on the hunt for ways of increasing workability without sacrificing the strength of the finished product. The process known as air entrainment allows contractors to achieve just this elusive goal.
Air-entrained concrete increases workability by introducing millions — if not billions — of microscopic air bubbles into the wet concrete. These air bubbles function almost like a sort of lubricant, allowing the larger chunks of aggregate to flow past one another more smoothly.
Be aware that air-entrained concrete still sacrifices a little bit of strength. Generally, the compressive strength of air-entrained concrete goes down by 3 to 7 percent. Most contractors consider this a reasonable trade-off for the workability benefits since adding extra water would reduce compressive strength to a much larger degree.
2. Water Resistance
There can be little doubt that the Achilles' heel of concrete is water. The porous nature of concrete allows water to easily penetrate it. This water expands as it freezes, creating stresses that may crack or weaken the concrete. A large percentage of concrete damage can be traced back to water.
Air-entrained concrete has a noteworthy advantage in this department. All of the void spaces created as the air bubbles harden give the concrete a natural buffer against freezing water. The bubbles' additional volume gives the freezing water room to safely expand. As a result, the water doesn't press against the concrete with nearly as much pressure.
Segregation is an unwanted phenomenon that occurs after concrete has been poured in place. It involves the separation of the concrete's main ingredients as heavier aggregate particles move downward towards the bottom of the slab. This downward migration gives rise to a closely-related phenomenon known as bleeding.
As the heavier particles move downward, they displace a certain volume of water — literally pushing it back upwards toward the surface. Excessive bleeding weakens the concrete by preventing the cement from fully bonding with the aggregate. The resulting slab will thus be much more likely to suffer from issues like cracking and spalling.
Air-entrained concrete reduces the ill-effects of segregation. Instead of pushing all the way back to the surface, the displaced water pushes into the air bubbles. While this reduces the number of bubbles, it performs a much greater good by allowing water to remain more evenly distributed throughout the slab.
Air-entrained concrete allows contractors to more easily install concrete surfaces while also promoting stronger results. For more information about whether air-entrained concrete would be a good choice for your next concrete project, please contact San Jose's experts at Jimenez Concrete Inc.