1722 - FIBROUS REINFORCEMENT FOR CONCRETE 1700-32
1722.1 Description
This specification covers both micro and macro fibers for use as reinforcement in concrete. Micro fibers are used to control plastic shrinkage cracks in concrete while macro fibers control cracking in hardened concrete and are often used as a substitute for traditional crack control st eel reinforcing bars or mesh. In addition, macro fibers add toughness, and impact and fatigue resistance to hardened concrete.
1722.2 Requirements
a. Micro fibers.
1.Provide fibers that are 100% virgin polypropylene, fibrillated, rough textured, interconnected fibers containing no reprocessed olefin materials and specifically manufactured as concrete reinforcement.
2.Provide fibers that are graded with a maximum length of 2 inches and a minimum tensile strength of 32 ksi. b. Macro fibers.
1.Provide macro synthetic fibers as defined in ASTM C 1116, Type III, and ASTM D 7508.
2.Provide fibers having a minimum length of 1.25 inches, a maximum length of 2.0 inches, and an aspect ratio (length divided by equivalent diameter) between 70 and 100, inclusive.
3.Provide fibers with a minimum tensile strength of 50 ksi.
4.Provide fibers, which when tested using the procedure described in subsection 1722.4b. , r e s u l t i n a minimum strength ratio (R e,3) of 25%.
1722.3 Test Methods – Micro Fibers
None specified.
1722.4 Test Methods – Macro Fibers
a. Determine the tensile strength of macro fibers using ASTM D 7508. b. Determine equivalent flexural strength ratio (R e,3) using ASTM C 1609 with the following modifications:
1.Utilize 6 x 6 x 20 inch (150 x 150 x 500 mm) beam specimens tested using an 18 inch (450 mm) span.
2.Test at least three beam specimens using the concrete mixture described below.
3.Test beam specimens when the concrete compressive strength is between 3,000 and 5,000 psi. Test three 6 x 12 inch cylinders to verify concrete compressive strength of beam specimens at testing. No single cylinder break shall deviate from the other breaks by more than 10% . Provided the average of th e three breaks is within the test limits described above, beam testing can proceed.
4.In addition to the strength requirements, use test concrete satisfying the following: 0.35 to 0.50 water cement ratio by weight no supplementary cementitious materials air-entraining admixtures only 50% coarse – 50% fine aggregate by weight maximum aggregate size: ¾” fine aggregate: naturally occurring (uncrushed) sand - no manufactured sand percent air by volume: 6.5±1.5% minimum fiber dosage: 4.0 lbs per cubic yard of concrete c. Testing shall be performed by a laboratory regularly inspected by the Cement and Concrete Reference Laboratory (CCRL) of the National Institute of Standards and Technology, or other approved reference laboratory. 1722 - FIBROUS REINFORCEMENT FOR CONCRETE 1700-33
1722.5 Prequalification
a. Manufacturers wishing to provide fibrous reinfo rcement for concrete for KDOT projects must be prequalified. b. Submit a small sample to the Bureau of Construction and Materials for prequalification. Include the following information:
1.Name, address and telephone number of the manufacturer and the preferred contact person.
2.Name of product and manufacturer’s recommended dosage rate or rates.
3.Technical data sheets.
4.Material Safety Data Sheets. In addition, submit either of the following:
5.For micro fibers - Test reports substantiating the requirements of subsection 1722.2a.
6.For macro fibers - Test reports substantiating the requirements of subsection 1722.2b. For the C 1609 requirements, include both the mix design of the test concrete, the compressive strength data of the test concrete at the time of beam testing, and the fiber dosage used during testing to satisfy the R e,3 requirements of subsection 1722.2b. c. The submittal will be reviewed and the manufacturer will be notified of the results. The Bureau of Construction and Materials will maintain a list of prequa lified fibrous reinforcement. For each prequalified macro fiber, a minimum fiber dosage, reported from subsection 1722.5b.(6), will be shown for each product.
1722.6 Basis of Acceptance
Prequalification as required by subsection 1722.5. Receipt and approval of a Type C certification as specified in DIVISION 2600. In addition, when macro fibers are being used as a substitute for 6 X 6 – W4 X W4 welded wire reinforcement in valley gutters and entrance pavement, provide a copy of the approved mix design with the prequalified fiber manufacturer, product name, and dosage clearly identified. Use a fiber dosage that is not less than the product’s value shown on the prequalified list.
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Source: Standard Specifications for State Road and Bridge Construction, 2015 Edition. Pages 822–823 of 978. View official source ↗