Faq

1. What is the function of polypropylene fibres ?
2. How to compare with other steel fibres ?
3. Do fibres ball during mixing ?
4. Can steel fibers be added at the ready mix plant ?
5. Can steel fibers be added on site ?
6. Do I still need dowels at construction joints when using steel fibers ?
7. Can steel fiber reinforced concrete be pumped ?
8. Will steel fibers protrude from the surface ?
9. Will steel fibers rust?
10. Are steel fibers compatible with curing compounds ?
11. Can abrasion resistant toppings and liquid sealants can be applied over steel fiber reinforced floors?
12. Will steel fibers damage my power trowel?
13. How do I cut joints on my steel fiber reinforced concrete slab?
14. How will steel fibers affect my flatness and levelness ratings?
15. How can I quantify the differences between various steel fibers?
16. What is meant by ductility?
 

 

1. What is the function of polypropylene fibres ?
The main property of these fibres is to reduce the formation of shrinkage cracks in freshly poured concrete. After the concrete has hardened the fibres have little further effect on crack control or provide any form of reinforcement.
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2. How to compare with other steel fibres ?
  Steel fibres come in many shapes and sizes each with different performance levels. To make a true comparison between different products and ensure the correct selection is made, it is recommanded that each potential supplier be asked to supply accredited test results for their products in accordance with one of the internationally recognised standards.
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3. Do fibres ball during mixing ?
  With Dramix glued fibres, this can be prevented as long as the mixing procedures of the product data sheets are followed.
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4. Can steel fibers be added at the ready mix plant ?
  Yes , introduce steel fibers after all other ingredients are already in truck. Set the truck mixer on charging speed and add fibers at a rate not to exceed 100 pounds/minute. Mix for a minimum of 40 revolutions at charging speed .
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5. Can steel fibers be added on site ?
  Yes, gradually feed fibers in the mix via conveyor or OHSA approved scaffolding .
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6. Do I still need dowels at construction joints when using steel fibers ?
  Yes, dowels are required at construction joints. Dowels at contraction joints are typically not required, due to aggregate interlock and steel fibers bridging the joint. Dowels may be required at contraction joints if spacing exceeds industry standards.
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7. Can steel fiber reinforced concrete be pumped ?
  Yes, but expect a 1 to 3 inch slump loss through the hose depending on the steel fiber dose rate, ambient temperatures and hose length. A mid-range water reducing agent (MRWR) is commonly used to enchance workability and ease of flow through pump lines. High-range water reducers (HRWR) may be required in some cases. Typically, a 4 to in. Diameter hose is required.
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8. Will steel fibers protrude from the surface ?
  Use of vibratory or laser screeds in conjunction with highway straight edges and power float finishers typically causes to fibers to lay flat . Reference Document
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9. Will steel fibers rust?
  Outdoor Applications With Cracks-Laboratory and field-testing of cracked SFRC in environments containing chlorides has indicated that the cracks in concrete can lead to corrosion of the fibers passing across the crack. However, hairline cracks (crack widths < 0.004-in.) do not allow corrosion of steel fibers passing across the crack. If cracks wider than 0.004-in. are limited in depth, the consequences of this localized corrosion are not structurally significant.
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10. Are steel fibers compatible with curing compounds ?
  Yes, common curing compounds produed by a host of major manufacturers including Master Builders, Grace, and Euclid are commonly used on SFRC floors.
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11. Can abrasion resistant toppings and liquid sealants can be applied over steel fiber reinforced floors?
  Yes, steel fibers are compatible with dry shake or spray-on toppings.
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12. Will steel fibers damage my power trowel?
  No, power blade trowels and disc floaters are commonly used to provide a flat and level surface without excessive wear to the blades .
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13. How do I cut joints on my steel fiber reinforced concrete slab?
  Both wet-cut and early entry saws are commonly used to form contraction joints. Cut the joints to 1/3 slab depth, if possible, per ACI 302.1R guidelines. Generally limit joint spacing to ACI and PCA recommendations for unreinforced concrete.
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14. How will steel fibers affect my flatness and levelness ratings?
  Flatness and levelness are generally not affected at dosages up to 70 pounds per cubic yards.
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15. How can I quantify the differences between various steel fibers?
  The residual strength factor (see below) is the most common factor used to differentiate steel fiber types. Steel fiber performance is a function of tensile strength, aspect ratio and anchorage.
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16. What is meant by ductility?
  Ductility is measured by beam - or plate tests. The value measured is post-crackresistance, expressed as equiv. Flexural strength (N/mm²) or energy absorbtion (J). The tests are standardized and used to describe the material property in order to provide the engineer with a design value and allows to specify the fiber concrete in an objective manner.
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