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Pavement Design. CEE 320 Anne Goodchild. Dictionary.com. Pavement: Noun a paved road, highway, etc. a paved surface, ground covering, or floor. material used for paving Sidewalk Pave: Verb
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Pavement Design CEE 320Anne Goodchild
Dictionary.com • Pavement: Noun • a paved road, highway, etc. • a paved surface, ground covering, or floor. • material used for paving • Sidewalk • Pave: Verb • to cover or lay (a road, walk, etc.) with concrete, stones, bricks, tiles, wood, or the like, so as to make a firm, level surface. • noun 2.Southern Louisiana. a paved road
What is Pavement: Wikipedia • Pavement (material), the durable surfacing of roads and walkways ("road surface" in British English) • Sidewalk, a walkway along the side of a road, in American English ("pavement" in British English and Philadelphia dialect) • Pavement (architecture), a floor-like stone or tile structure • Pavement (band), an indie rock band from Stockton, California • Pavement (magazine), a youth culture magazine, published in New Zealand • Pavement Records, a record label • Portuguese pavement, the traditional paving used in most pedestrian areas in Portugal ("Calçada Portuguesa" in Portuguese) • Road surface marking, highway surface markings intended to convey information • Limestone pavement, a naturally occurring level outcrop • Tessellated pavement, a rare sedimentary rock formation that occurs on some ocean shores
Outline • Pavement Purpose • Pavement Significance • Pavement Condition • Pavement Types • Flexible • Rigid • Pavement Design • Example
Pavement Purpose • Load support • Smoothness • Drainage • All weather operation • Direction andguidance DC to Richmond Road in 1919 – from the Asphalt Institute
Pavement Significance • How much pavement? • 4 million centerline miles in U.S. • 2.5 million miles (63%) are paved • 8.37 million lane-miles total • Largest single use of HMA and PCC • Costs • $20 to $30 billion spent annually on pavements • Over $100 million spent annually in WA • Many states over billion dollar budgets
Interstate Highway System • Largest highway system in the world • Largest public works project in history • Started construction in 1956 • 90% federal, 10% state funding • Owned built and operated by states • Construction and maintenance costs primarily provided by fuel tax
Resources • Pavement Interactive • State DOTs • AASHTO
Pavement Design Procedures • Asphalt Institute method • National Stone Association procedure • Shell procedure • AASHTO Guide for Design of Pavement Structures – American Association of State Highway and Transportation Officials • First published in 1972
What makes it difficult • Construction process control • Material variations • Exposed environment • Temperature and weather variability • Transportation of materials • Cost of materials • Unkown traffic loads
Pavement Types • Flexible pavements • Asphalt • Rigid pavements • Concrete
Pavement Types • Want to distribute the load to avoid permanent deformation
Vehicle loads • Typical vehicle weighs about 3500 lb, tire pressures around 35 lb/in2 • Truck can weigh up to 80,000 lb with tire pressure of 100 lb/in2 • Trucks and busses present a much more significant load on the pavement.
Vehicle Volume • Pavements have a design life, and fail after cumulative vehicle exposure. • Volume of vehicles and prediction of vehicle volume is fundamental to pavement design.
Pavement Condition • Defined by users (drivers) • Develop methods to relate physical attributes to driver ratings • Result is usually a numerical scale
Pavements degrade over time due to Exposure to traffic Time Exposure to elements Different for different materials and different construction methods Serviceability Concept
What pavement thickness is required to sustain X vehicle loads of Y weight?
Pavement Types • Flexible Pavement • Hot mix asphalt (HMA) pavements • Called "flexible" since the total pavement structure bends (or flexes) to accommodate traffic loads • About 82.2% of paved U.S. roads use flexible pavement • Rigid Pavement • Portland cement concrete (PCC) pavements • Called “rigid” since PCC’s high modulus of elasticity does not allow them to flex appreciably • About 6.5% of paved U.S. roads use rigid pavement
Flexible Pavement Base: higher strength material than subbase, often a cementing material is used. Cementing material can be portland cement or asphaltic cement, or other material.
Flexible Pavement • Structure • Surface course (waterproof, anti-skid) • Base course • Subbase course • Subgrade
Types of Flexible Pavement Dense-graded Open-graded Gap-graded
Rigid Pavement • Structure • Surface course • Base course • Subbase course • Subgrade
Types of Rigid Pavement • Jointed Plain Concrete Pavement (JPCP) Joints accommodate shrinkage during drying.
Types of Rigid Pavement • Continuously Reinforced Concrete Pavement (CRCP) Photo from the Concrete Reinforcing Steel Institute