Planning for slab-on-ground placement

Chapter 1

Chapter Topics

• Introduction• Specification requirements• Determining the size of concrete placements• Ordering concrete• Concrete delivery• Equipment• Size of placing and finishing crews• Preconstruction meeting

Specification Requirements

• ACI flatwork finishers• Material properties• Concrete strength and durability• Vapor retarders or barriers• Reinforcement• Slab flatness and levelness• Joint spacing and depth• Curing and protection

Concrete Delivery

• Concrete is perishable—be prepared• Site access—flagger needed—cone area• Space for two trucks to discharge• ASTM C 94 Specification for Ready-Mixed Concrete– Discharged within 1 ½ hrs or 300 revolutions

• Plan for ready mix trucks– Spacing of trucks, 15 minutes?– Discharge of trucks, 5 to 15 minutes– Washout of trucks

Have Equipment Ready

• And spare equipment• Emergency bulkheads• Equipment Producitivity– Hand finishing crew: 1000 to 2000 sf– Walk-behind: 1000 to 3000 sf– Ride-on trowel: 3000 to 6000 sf– Laser-guided, wheel-mounted screed: 30,000 to

50,000 sf

Size of Placing and Finishing Crews

• Labor cost for placement• Workers sick or injured• Concrete sets faster• Weather changes; hot or rain• Equipment breakdowns• Early sawing to minimize cracking• Overlap placing and finishing crews

Placing Crew

• Finishing foreman• Discharging concrete• Spreading concrete• Screed operators• Finishers• General assistance

Finishing Crew

• Concrete and Weather• Working edges• Walk-behind to float fast-setting loads• Riding trowels• General assistance

Checklist for Placing and Finishing

• Volume of concrete• Concrete delivery rate• Haul time• Truck spacing• Placing equipment• Spare equipment• Crews

End of Chapter 1