Ron Kozikowski

Fcp Ron Kozikowski 10844036

Ron Kozikowski, PE, a construction and materials engineer with North Starr Concrete Consulting, P.C., can be reached at [email protected].

Construction schedules and contractor economics typically require concrete placements of 10,000 to 20,000 square feet or from 30,000 to 50,000 square feet when a Laser Screed is used. This figure shows a 300,000 square foot pour that was completed within 24 hours in a single concrete placement.

Specification Limits on Slab-on-Grade Placement Size

ACI 302 has stated since 1980 that a limited placement size concept has not achieved any better shrinkage results, is more expensive, and adds time to the schedule.

The penetrations required in this depressed area in an elevated floor slab make it difficult to use 10-foot straightedges and riding power trowels. Specifiers should consider these multiple obstructions to finishing operations when determining F-number values. In this case, the specifier required F-numbers in the small depressed floated area that was to receive ceramic tile for bathrooms.

The Limitations of F-Number Specifications

Contractors need to be cognizant of certain situations that make it difficult to achieve routine FF and FL requirements and know how to get those specifications changed to more reasonable requirements.