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• FORTA-FERRO®

Reduced Joint/Manufacturing Floor Slab

Project Description:

Since its introduction in late 1999, FORTA-FERRO® structural synthetic fiber has been used in thousands of precast and site-cast concrete applications as a viable alternative to conventional reinforcing steel. Performance benefits of this long-length heavy-duty fiber include improvements to concrete toughness, and dramatic reductions to shrinkage cracking and subsequent slab curling. As a result of these improved characteristics, project designers began to investigate the possibility of extending conventional joint spacing in slabs and floors in order to minimize the cost of joint installation, joint filling, and ultimate joint repair. In an effort to expand the joint-space envelope and to determine future spacing thresholds, FORTA® and project floor consultant Jerry Holland of Structural Services, Inc. decided to use the FORTA® production plant addition in the spring of 2004 as a test placement to validate the technology.

The 18,000 square foot L-shaped addition to the FORTA® production and warehouse facility was divided into two large slabs (115 feet x 85 feet and 127 feet x 60 feet) separated by a construction joint using Diamond-Dowels as the load-transfer system. Original contractor plans called for sawcut joints on 15-foot centers, amounting to over 2,150 feet of sawcuts (click here for layout plans). The use of the FORTA-FERRO® allowed for the elimination of the sawcuts and joint-fill, as well as the elimination of the conventional steel reinforcement grid in this 6" thick floor.

The FORTA-FERRO® fiber was used at a dosage of 0.5% by volume (7.5 pounds/cubic yard) in a 4,000 p.s.i. design mix (click here for mix design). The FORTA-FERRO®-reinforced concrete was placed on a double layer slip-sheet membrane to allow for movement over compacted base material. The slab was placed with a laser-screed, finished with a machine-trowel polished surface, and water cured for 7 days.

Though slab #2 (115 feet x 85 feet) has developed a crack at approximately 60 feet on the longest side, slab #1 (127 feet x 60 feet) remains crack-free at over five years of age. Floor flatness numbers are very respectable even though the floors were not constructed as super-flat slabs, and the floors are considerably flatter and more level than a typical floor, suggesting a significant reduction in slab curling than would be expected over these distances (click here for 6 month results). FORTA Corporation and consultant Jerry Holland continue to monitor this and other similar projects in order to estimate and predict the ability of this high-volume fiber to affect traditional joint-space practices.

Project Photos: Click on a photo for larger view.

• General Contractor: Struxures, Inc., Seneca, PA
• Concrete Contractor: Maya Brothers, Inc., Erie, PA
• Floor Consultant: Jerry Holland/Structural Services, Inc., Atlanta, GA
• Concrete Supplier: R. W. Sidley, Grove City, PA
• Flatness Testing: Professional Services, Inc., Pittsburgh, PA

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