TEST REPORT: Residual Strength at Various Fiber Dosages: FORTA-FERRO®

SUMMARY: FORTA-FERRO® is recognized in the industry as a next-generation, macro or structural synthetic fiber. These fibers have shown the ability to dramatically improve concrete residual strength – the ability to carry load after initial crack. This residual strength/post-crack result allows engineers and designers to determine the appropriate dosage of fiber that will fulfill the reinforcement requirements for a specific project application. Research was performed to provide these performance values to the design community for various dosage levels of the FORTA-FERRO® structural synthetic fiber.

RESEARCH PARTICULARS: The various fiber dosages were included in identical concrete mixes, and were mixed, placed, and tested in the same manner. Fiber-reinforced cylinders (4 in. x 8 in. / 100 mm x 200 mm) were cured in a fog room at 85-100% humidity, and tested for compressive strength per ASTM C-39 procedures at 28 days. Compressive results were reported as an average of three specimens at each fiber dosage. Fiber-reinforced flexural beams (4 in. x 4 in. x 14 in. / 100 mm x 100 mm x 350 mm) were also cured in a fog room, and then tested for residual strength per ASTM C-1399 procedures at 28 days. Average Residual Strength (ARS) results were recorded in p.s.i., using the average of six specimens at each fiber dosage. The fiber dosages involved in both compressive and residual strength testing were 3.0, 5.0, and 7.5 lbs./cubic yard (1.8, 3.0, and 4.5 kgs./cubic meter).

RESULTS: Compressive Strength and ARS values for 2-1/4”/54mm FORTA-FERRO®

Dosage Compressive Strength ARS 3.0 lb./cubic yard (1.8 kg./cubic meter) 6,500 p.s.i (44.8 MPa) 126 p.s.i. (.869 MPa)

5.0 lb./cubic yard (3.0 kg./cubic meter) 6,110 p.s.i (42.1 MPa) 185 p.s.i. (1.276 MPa)

7.5 lb./cubic yard (3.6 kg./cubic meter) 5,860 p.s.i (40.4 MPa) 260 p.s.i. (1.8 MPa)

[From: “Average Residual Strength Comparisons of Synthetic Fiber Reinforced Concrete”, South Dakota School of Mines and Technology, Dr. Anil Patnaik, May 2007.]

CONCLUSION: The compressive strength results were quite similar for each fiber dosage, with differences falling well within the normal deviation of the test method. These results would support the idea that fibers are not expected to affect the first-crack compressive strength of the concrete. As would be expected, the ARS results increased as fiber dosage increased. The ability of these macro/synthetic fibers to hold cracked concrete together is significant and considerable, especially at the higher 5 and 7.5 pound dosages in the range of 200+ p.s.i. These ARS performance levels may be used with confidence by the design engineer to calculate the reinforcement needs for a specific project or application.

FORTA® personnel are available to assist with fiber selection and use, as well as the explanation of reasonable expectations of the fiber. FORTA® representatives do not engage in the practice of engineering or architecture as licensed by government agencies, nor are they licensed to act in a role of overall project supervision where FORTA® products are used. FORTA® personnel are available solely for the support of our customers - those that purchase and specify our products.

U. S. A. REPORT #20-05

• Compressive Strength • Residual Strength

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FORTA-FERRO®, and are registered trademarks of FORTA Corporation