Concrete Fiber Mesh: What is Fiber Mesh and What Does it do?
What is Fiber Mesh in Concrete?
Concrete companies are always trying to find ways to improve their mix designs, mainly trying to make a concrete mix that is more durable and longer-lasting. Enter fiber mesh additives.
There are a few different types of fiber additives. The most common mesh among our residential customers is fiberglass mesh. This mesh is made from fiberglass, they are approximately ½”-1” long fibers and are added to the concrete during the batching process. Ordered as “residential fiber”, we add a 1# bag of fibers to each yard of concrete. A 10-yard order will have 10 x 1# bags of fiber added to the mix. Once the concrete has cured, those tiny fibers mixed throughout the concrete create a web-like structure.
1# bag micro fiber mesh
What Does Fiber Mesh Do?
Fiber does not increase the strength of concrete. A 3000psi mix will have the same compressive strength with or without a fiber additive. However, fiber will increase the concrete strength after cracking, this is known as “toughness”. Once the concrete is cracked, the toughness provided by the fibers will help keep the crack from getting bigger and completely breaking off.
There is a saying in the concrete business “concrete does two things: it gets hard, and it cracks”. Having fiber in the concrete keeps cracks small and prevents them from turning into catastrophic problems.
In a previous article about air entrainment, we talked about the freeze/thaw cycle. Fibers are beneficial in resisting freeze/thaw scaling.
Another benefit of keeping cracks small is that it prevents outside contaminants from getting in and further deteriorating the concrete.
Fiber is highly beneficial in preventing plastic shrinkage. Pouring concrete on hot, sunny, and windy days can be a challenge. The bleed water at the surface can evaporate faster than the rest of the concrete can cure. This leads to what is known as plastic shrinkage; cracks on the surface from the uneven curing process. Fibers can aid in preventing plastic shrinkage from becoming prominent. So if your job is in the direct sun on a 90-degree day, adding fiber is definitely something to think about.
Cracks From Plastic Shrinkage
What are the drawbacks of using fiber?
Cost: Adding fiber costs $6/yard. For smaller jobs, this isn’t much of an issue. However, with larger jobs, the cost can add up quickly.
Fibers are randomly distributed during the mixing process. There is no guarantee the fiber will be correctly aligned in the concrete in the areas likely to crack. Ideally, the fiber would be concentrated in the areas where a crack is most likely to occur. But this isn’t possible. Because of this, fiber is not a replacement for using rebar. Rebar can be placed precisely where it is needed most.
Should I use fiber in my concrete mix?
Choosing to use fiber mesh in a concrete mix will depend on the application. However, if it were my project, I would use fiber in almost all flat work jobs; driveways, patios, walkways, and slabs. The extra cost is well worth the added security of having a long lasting quality concrete finish.
If you are looking for a concrete delivery in the Mooresville, Statesville, Davidson, Cornelius, Huntersville, China Grove, Kannapolis, Sherrills Ford areas of North Carolina, give us a call for more information. 908-281-3131
