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PAVEMENTS. Pavement Types and Materials. Pavement Purpose. Load support Smoothness Drainage. DC to Richmond Road in 1919 – from the Asphalt Institute. Pavement Condition. Pavement Condition. Pavement Condition. Pavement Types. Rigid Pavements. Flexible Pavements. (WSDOT, u.d.).
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PAVEMENTS Pavement Types and Materials
Pavement Purpose • Load support • Smoothness • Drainage DC to Richmond Road in 1919 – from the Asphalt Institute
Pavement Types Rigid Pavements Flexible Pavements (WSDOT, u.d.) Composite Pavements
Flexible Pavement • Structure • Surface course • Base course • Subbase course • Subgrade
Higher AV (%) Higher Permeability Higher Macrotexture Asphalt Concrete Mix Components Aggregates Air Void Asphalt Binder Gap Graded Mixes Dense Graded Mixes Open Graded Mixes
Types of Flexible Pavement Dense-graded Open-graded Gap-graded
Adjusts to limited differential settlement Easily repaired Additional thickness added any time Non-skid properties do not deteriorate Quieter and smoother Tolerates a greater range of temperatures Loses some flexibility and cohesion with time Needs resurfacing sooner than PC concrete Not normally chosen where water is expected Flexible Pavements Advantages Disadvantages
Dynamic Modulus, E* Stiffness property Function of Temperature rate of loading Age binder stiffness aggregate gradation binder content air voids Inputs Asphalt mixture properties Asphalt binder Air voids Asphalt Mix
Rigid Pavement • Structure • Surface course • Base course • Subbase course • Subgrade
Good durability Long service life Withstand repeated flooding and subsurface water without deterioration May lose non-skid surface with time Needs even sub-grade with uniform settling May fault at transverse joints Rigid Pavements Advantages Disadvantages
Types of Rigid Pavement • Jointed Plain Concrete Pavement (JPCP) • Jointed Reinforced Concrete Pavement (JRCP)
Types of Rigid Pavement • Continuously Reinforced Concrete Pavement (CRCP)
Rigid Pavement – Construction Slipform Fixed form
Rigid Pavement Terms • S’c (PCC modulus of rupture) • A measure of PCC flexural strength • Usually between 600 and 850 psi • J (load transfer coefficient) • Accounts for load transfer efficiency • Lower J-factors = better load transfer • Between 3.8 (undoweled JPCP) and 2.3 (CRCP with tied shoulders) • Ec (PCC elastic modulus) • 4,000,000 psi is a good estimate • k (modulus of subgrade reaction) • Estimates the support of the PCC slab by the underlying layers • Usually between 50 and 1000 psi/inch
Pavement Structure • Bedrock • Presence within 10 feet of the pavement surface influences the structural response of the pavement layers • Inputs • Layer thickness (infinite) • Unit weight • Poisson’s ratio • Layer modulus
Subgrade • Characterized by strength and/or stiffness • California Bearing Ratio (CBR) • Measures shearing resistance • Units: percent • Typical values: 0 to 20 • Resilient Modulus (MR) • Measures stress-strain relationship • Units: psi or MPa • Typical values: 3,000 to 40,000 psi
Subgrade Some Typical Values