Menu
DIRECTIONS FOR GOOD SURFACE FINISHING APPLICATION

1

The correct fiber reinforcement geometry should be preferred according to the application area.

  • It's recommended to use Polytwist® fiber reinforcement product which has twisted fiber geometry to have the best finishing results
  • This geometry prevents the fibers from clumping in their packaging bag and ensures their homogeneous distribution in the concrete.
  • Polytwist®, designed in a geometry that can be embedded into concrete easier during the finishing process, provides a flawless surface appearance with correct application.
  • Polytwist® is specially produced in concrete gray color so that the near-surface fibers match the concrete appearance.
Figure 1: Polytwist PT54 with twisted geometry

2

Concrete mix design specific to the project should be prepared.

  • It's recommended that the slump of the fiber-added concrete be at 100-150 mm (4" - 6").
  • The concrete mix design must be prepared according to the parameters specific to the relevant project notes. It is highly recommended that the water/cement ratio does not exceed 0.55 unless there are special exceptions.
  • One of the frequently made mistakes in the slab on grade, floor concrete applications; is the addition of water to the concrete mixer on site. The water more than the original amount in mix design should not be added to the concrete. If added, it may reduce the strength of the concrete and cause fibers to appear on the concrete surface.
Figure 2: Slab on Ground Application

3

Attention should be paid to common application mistakes that can be encountered frequently during concrete pouring.

Concrete applications are dynamic productions that depend on many parameters. Even if the concrete is produced with the right mix design and materials, mistakes made in its application in the field may prevent the quality of the work from being at the desired level. The general rules to be considered in concrete casting are listed below;
  • Extra water should not be added to the concrete once dispatched from the plant.
  • Compliance of the concrete mix design in different mixers should be checked.
  • Concrete should be poured from a max. height of approximately 50 cm (2 ft), necessary precautions should be taken to prevent segregation, and if segregation is detected, the concrete plant should be contacted to resolve the problem.
Figure 3. Example of Concrete Pouring Height
Figure 4. Screeding with Laser Screed Machine

4

The instructions to be followed before and while finishing concrete surface and during applying surface hardener.

Dry shake surface hardener materials produced specifically for different surface wear performances have various mixtures such as quartz aggregate, corundum aggregate, silica aggregate, etc. Surface hardeners, if applied correctly, make a serious contribution to obtaining a quality surface appearance in fiber-reinforced floor concretes.
Figure 5: Double Disc Power Troweling Application
The following instructions are given below for best practices of finishing:
  • If a 3-5 mm (~l/8") deep footprint is formed when stepping on the concrete, it is largely ready for finishing application.
  • Fiber reinforced concrete bleeds less and slower than conventional reinforced concrete, and the concrete completes bleeding slightly later than usual. The surface finishing process should be started considering that state.
  • Before finishing, it should be ensured that the surfaces of all equipment in contact with the concrete are clean and smooth.
  • Before laying the surface hardener, it is recommended to apply bull float or 1-2 passes of float power trowelling with pan for surface preparation.
  • If the paste on surface joggles and deforms during the pan finishing process, the application should be paused and waited for 10-15 minutes. The effect of scattering concrete paste around creates undulation on the surface, it also brings out the fibers already embedded in the surface and causes the fiber to appear on the surface.
  • If dry shake hardeners are laid by machine; it should be spread homogeneously on the surface at one time.
  • If laid by hand and the surface hardener dosage is above 4 kg/m2 (~0.8 psf), it should be laid in two stages. 2/3 of the consumption in the first stage, 1 /3 of the consumption in the second stage, the second stage should follow the first stage immediately.
  • The surface hardener should not be spread more than 1 m (-3 ft) away to prevent undulation, get smooth surface and homogeneous look.
  • Water should never be added to the surface on which the surface hardener has been applied.
  • After the float trowelling with pan, proceed to trowel with blades finishing process. The metal polishing blades of the trowel should be set straight at a minimum angle, especially for the first two passes, and the blades should be perpendicular to each other.
  • In subsequent rounds, the blades should be angled gradually.
  • The final finishing application step should be done at high speed after the concrete has hardened enough to walk on without leaving any marks.
  • Finishing operations should not be done under direct sun or windy weather conditions.
  • Double disc heavy machines should be preferred in order to keep the undulation on the surface at a minimum during finishing. Especially if corundum aggregate surface hardener is used, more care should be taken.
  • When using a concrete finishing broom or hand trowel, care should be taken to ensure that the movement is only in one direction. Back and forth movements on the surface should be avoided so that the surface is not over-eroded and the fibers do not come up and be pulled back to the surface.
  • If the precautions in terms of concrete quality and workmanship are not implemented correctly so that visible fibers are too much on the surface, these fibers can be burned quickly from the surface by blowtorch that applicator can employ easily if desired.
Figure 6. Using the Broom Concrete Brush

5

Homogeneous Mixture of Fiber Reinforcements in Concret

The following instructions are given below for the best fiber mixing practices:
  • Synthetic fibers can be mixed at the concrete batching plant by the addition of fibers to a central mixer.
  • Alternatively, can be mixed in a concrete mixer truck during hi-speed rotation and continuing that for at least 5 minutes after the last bag of fiber is added to the truck. Never add fibers at slow or cruise speed rotation.
  • In any mixing method, do not add fibers as the first mix ingredient.
  • If a conrete pump is to be used for the placement, care should be taken to ensure that the mesh grates are made of round bars on the hopper so fibers can slide in with ease.
Figure 7. Addition of Fibers to Concrete Mixer Truck
Figure 8. Addition of Fibers to Central Mixer