A concrete pavement is to be constructed for a 4-lane urban expressway on a subgrade with an effective modulus of subgrade reaction k of 100 lb/in3. The accumulated equivalent axle load for the design period is 3.25 × 106. The initial and terminal serviceability indices are 4.5 and 2.5, respectively. Using the AASHTO design method determine a suitable thickness of the concrete pavement, if the working stress of the concrete is 600 lb/in2 and the modulus of elasticity is 5 × 106 lb/in2. Take the overall standard deviation, So, as 0.30, the load transfer coefficient, J, as 3.2, the drainage coefficient as 0.9, and R=95%.
What will be an ideal response?
First, determine the design serviceability loss
design serviceability loss = 4.5 – 2.5 = 2.0
From the nomographs provided in Figures 20.13 and 20.14 and using the factors
above, the required thickness of the concrete slab is 9.4 inches, which for design
may be rounded up to 9.5 inches, the nearest half-inch for design.
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What will be an ideal response?
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Fill in the blank(s) with the appropriate word(s).
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