Construction loading of slab-on-grade

[sapperDAK]

To finish a combination asphalt and concrete road network, the contractor wants to use a construction process which slipforms the curbing first, then places the 10-inch thick reinforced concrete turnpads at intersections, followed by the asphalt paving between the concrete turnpads. Question is how long should the contractor wait before placing construction loads of the paver and loaded asphalt trucks on the concrete turnpads. f'c = 4,000-psi with #3 bar both ways at 12-inches O.C. Your perspectives please!

 

[civilperson]

When the field cured cylinders, (under a tarp on top of the turnpads), achieve 90% of F'c. Probably 14-20 days depending on temperature.

 

[cvg]

depends on the subgrade, subbase and base conditions as well as the strength of the concrete paving. 10 inch thick with 4,000 psi concrete and reinforcing seems like a lot. were the turn pads overdesigned? If so, then maybe you don't need to wait so long.

 

[sapperDAK]

Thanks guys! Here's some more info.
- Allowable soil bearing capacity = 3,000 psf
- Minimum 24-inch thick subgrade compacted to 95% modified proctor for both asphalt and concrete areas.
- 4 1/2-inch thick base course of 2A modified (well-graded crushed stone) aggregate compacted to 95% modified proctor for concrete areas.
Turnpads and roads were designed for traffic loads of military vehicles up to 70 tons.

 

[cvg]

first, decide if you can allow something less than 4,000 psi for the construction load. Common design for freeways is only 3,000 psi at 28 days. Then ask the supplier to provide data on 3-, 7- 14- and 28-day strengths and plot your curve. See if you can't get to about 3,000 psi after 10-days. If you really want to speed things up, go with a high early strength mixture, you can get up to 3,500 psi in 24 hours.

http://www.pavement.com/Concrete_Pavement/Technical/FATQ/Design/High_Early_Strength_Concrete.asp

http://www.pavement.com/Concrete_Pavement/Technical/Fundamentals/