|
 |
 |
 |
 |
 |
|
 |
 |
||||
Why add fibers to ready-mix concrete? Fiber additives have been used as a way to strengthen concrete since the mid-1990s. Materials specialists in the carpet industry suggested the idea, which quickly took hold as a way of reinforcing concrete “from the inside out,” making it more resistant to cracking and weathering while eliminating the need for welded wire mesh and other forms of metal reinforcements. How do these additives strengthen concrete? Fibers are added to the concrete mix before placement. Their unique structure ensures that they are evenly distributed through the mix so that after the pour, they remain in every cubic inch of the finished concrete. So, unlike wire mesh or even rebar, they strengthen the concrete in all directions. What benefits do fibers deliver? Longer concrete life. Fibers block the formation of capillary pores – small internal spaces that form as concrete cures. They also work against the formation of stress cracks. Without these flaws, outdoor concrete resists weathering and indoor surfaces hold up better against everyday stress. “The few cracks that may show up are held tight by the fibers, increasing the life of the material,” explains Brad Huiner, Prairie fibers expert. Labor savings. Adding fibers to the mix eliminates the need to store and install wire mesh, reducing costs for any project. In some cases, steel fiber additives can even replace steel rebar. In Europe, builders are using these additives to create flat floors without joints, further reducing labor and installation time. Enhanced crew safety. Injuries from the handling and placement of sharp, rusted wire mesh and rebar are eliminated with fiber additives. What kinds of fibers are used? Modern fiber additives are made of steel or synthetic materials such as polypropylene (PP). There are three kinds of PP fibers: 1) monofilament, which are smooth, slender strands; 2) fibrillated fibers, which have a notched or “fuzzy” surface; and 3) macrofiber additives, which are structured like tiny fishing nets. Each kind of PP fiber has unique advantages. For example, thin monofilaments can be added to concrete in large volumes, creating a dense network of support within the finished material. Fibrillated strands work in much the same way but offer more adhesion points for concrete to bond to, further enhancing its compressive and tensile strength. Macrofibers are the ultimate reinforcers, replacing heavy-gauge wire mesh and even rebar (up to #4 gauge). Steel fibers are another means of achieving internal strength without mesh or rebar. These fibers are being used to create joint-free floors and replace steel rebar and cages in other large-scale pours. I’ve heard stories about “hairy concrete.” Is there a way to combat that problem? In the early days of fiber additives, strands sometimes penetrated the surface of finished concrete. Newer additives and placement techniques have been developed to eliminate this problem, says Kevin Mahoney, product expert with BASF Master Builders. “We have fiber mixes now that lay down smoothly and finish perfectly, giving an ideal appearance in floors, driveways and patios,” he says. Where can I learn more about fiber additives for my upcoming jobs? Contact Brad Huiner at Prairie Material, 708.563.5856 or bhuiner@prairie.com to find out more about specifying fiber additives for your next project. Where fibers make a difference
|
