The composite k-value of this pavement structure can be assumed to be 300 pci. The projected 30-year design traffic in the truck lane (design lane) is listed in Table 3. Dowel and concrete shoulder will be used. Based on AASHTO rigid pavement design, please answer the following questions: a) What is the expected ESALs for this pavement system assuming the concrete slab is 9 inches? b) What is the design effective modulus of subgrade reaction k-value assuming the concrete slab is 9 inches? c) Using the information obtained in a) and b), what is the required thickness of the concrete surface layer with dowels and a tied concrete shoulder? d) Using the information obtained in a) and b), what is the required thickness of the concrete surface layer with dowels and an asphalt concrete shoulder? e) Using the information obtained in a) and b), what is the required thickness of the concrete surface layer with an asphalt concrete shoulder but without dowels? Table 3: Design Traffic in Truck Lane Single Axle Loads Expected Tandem (kips) Repetitions for 30 Loads (kips) Years (Single Axles) 32 8,000 60 30 30,000 56 28 80,000 52 26 125,000 48 24 165,000 44 22 310,000 40 20 425,000 36 18 550,000 32 16 635,000 28 14 705,000 24 Axle Expected Repetitions for 30 Years (Tandem Axles) 5,000 15,000 60,000 75,000 90,000 140,000 185,000 290,000 420,000 285,000 PCA Method Consider using the PCA design procedure to perform a design of pavement of above problem. The design concrete modulus of rupture at 28-day is 750 psi. A non-erodible 6-inch asphalt concrete subbase layer with a design stiffness of 200 ksi will be used to provide uniform support to the slab.
The reliability is 95% and a change in present serviceability is 2.0. Soil tests have found that the resilient modulus to be the following: spring = 2 ksi, fall = 3 ksi, summer = 4 ksi, and winter = 5 ksi. The rigid pavement structure will be built on a poorly draining silty-clay subgrade with 25% of time exposed to moisture levels approaching saturation. The concrete pavement will have 15-foot uniform joint spacing with a 12-foot slab width. tied concrete shoulder and dowels and an asphalt concrete shoulder, will be considered for the pavement section. Two concrete pavement design alternatives, dowels and 8 ft. Rigid Pavement Design AASHTO Method The pavement consists of a 4-lane pavement section (in two directions).
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