Batching Tips – Macro Fibers

Fibermesh macro fibers are referred to as structural fibers and are intended to carry load and therefore, used to replace traditional reinforcement in certain non-structural applications as well as minimize and/or eliminate both early and late age cracking.

Fibermesh macro fibers are to be added to the concrete mix at any point during the batching or mixing process. Fibermesh macro fibers may be added to:

The concrete must be mixed at high speed for 5 minutes, or 70 revolutions, after the addition of Fibermesh macro fibers to ensure uniform distribution.  Mixing time may vary due to wear on blades, blade arrangement and cleanliness of mixer.

Fibermesh macro fibers are compatible with admixtures. Synthetic macro fibers in concrete are purely mechanical and will not affect the concretes chemistry.

Depending on the Fibermesh macro fiber, the product is available in especially designed packaging that disintegrates and disperses the fibers throughout the mix. See individual data sheets for packaging details:

The addition of fibers into concrete tends to reduce the slump of concrete. This reduction in slump is “apparent,” or it appears to suffer from a loss of workability or it appears very stiff.  The concrete can actually become very fluid with the use of vibration.  The addition of fiber increases surface area in the concrete matrix, also the fibers can hold aggregate in place (reduce segregation); this combination contributes to the apparent slump loss. A rough estimate is that the expected reduction in slump for synthetic macro fibers is about 1 inch (25.4 mm) for every 3 pounds per cubic yard (1.8 kg/m³) of fiber.

The use of super-plasticizers or mid-range water reducers will assist in increasing the workability without altering the water cement ratio.

It is recommended that a trial batch is performed, to ensure that any adjustments necessary are made.

See Fibermesh macro fibers data sheets for recommended minimum dosages.