Repeat Problem 20-19, using the PCA design method, if the subgrade k value is 50 and a 6-inch stabilized subbase is used. The modulus of rupture of the concrete is 600 lb/in2 and the pavement has aggregate interlock joints (no dowels) and a concrete shoulder.
What will be an ideal response?
First, determine the estimated ESALs:
2-axle (12,000 lb) single unit trucks:
ESAL = 2(0.4)(28.28)(24,000)(365)(0.40)
ESAL = 79.27 × 106
3-axle (16,000 lb) single unit trucks
ESAL = 3(0.1)(28.28)(24,000)(365)(0.40)
ESAL = 29.73 × 106
Subgrade k = 50 lb/in3
For 6 inch stabilized subbase, determine effective k from Table 20.22:
k = 230 lb/in3
Assume a slab 6.5 inches thick with aggregate interlock joints and concrete
shoulders.
From Table 20.24, obtain equivalent stress values and then interpolate for
effective k,
Equivalent stress = 260 – ((260 – 243) × (30 / 100)) = 254.9
Stress Ratio = 254.9 / 600 = 0.42
From Table 20.28, determine the erosion factor of 2.80
12,000(1.2) = 14,400
16,000(1.2) = 19,200
The 6.5 inch slab is adequate under fatigue analysis but not for the erosion
criterion.
Assume a slab 8 inches thick with aggregate interlock joints and concrete
shoulders.
From Table 20.28, determine the erosion factor of 2.56
12,000(1.2) = 14,400
16,000(1.2) = 19,200
The 8 inch slab is adequate, check a 7.5 inch slab.
Assume a slab 7.5 inches thick with aggregate interlock joints and concrete
shoulders.
From Table 20.28, determine the erosion factor of 2.56
12,000(1.2) = 14,400
16,000(1.2) = 19,200
The 7.5 inch slab is inadequate, use a 8 inch slab depth.
You might also like to view...
Insufficient energy in the feed of animals results in all BUT which of the following problems?
a. increased hair growth c. decreased resistance to infectious disease b. loss in body weight d. reduced fertility
The term ____________________ aggression refers to aggression directed toward other members of the same species
Fill in the blank(s) with correct word
A mentor performs all of the following EXCEPT _______
A) Offers advice on how to do a job B) Signs paychecks C) Helps guide diagnosis of a problem D) Advises on professional behavior
A wound rotor motor has been recently put back into service but is now rotating in the wrong direction. After
examining the motor, you find that lead L1 is connected to T2, L2 to T3, and L3 to T1. To correct the rotation, you should: a. Connect L2 to T1, L3 to T2, and L1 to T3. b. Connect L1 to T1, L2 to T3, and L3 to T2. c. Connect L1 to T1, L2 to T2, and L3 to T3. d. Reverse phase connections between the wound rotor and the resistor bank.