CEE 320 Spring 2007 Pavement Design CEE 320 Anne Goodchild

CEE 320 Spring 2007 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

CEE 320 Spring 2007 What is Pavement: Wikipedia Pavement (material), the durable surfacing of roads and walkways ("road surface" in British English)Pavement (material) Sidewalk, a walkway along the side of a road, in American English ("pavement" in British English and Philadelphia dialect)Sidewalk Pavement (architecture), a floor-like stone or tile structurePavement (architecture) Pavement (band), an indie rock band from Stockton, CaliforniaPavement (band) Pavement (magazine), a youth culture magazine, published in New ZealandPavement (magazine) Pavement Records, a record labelPavement Records Portuguese pavement, the traditional paving used in most pedestrian areas in Portugal ("Calçada Portuguesa" in Portuguese)Portuguese pavement Road surface marking, highway surface markings intended to convey informationRoad surface marking Limestone pavement, a naturally occurring level outcropLimestone pavement Tessellated pavement, a rare sedimentary rock formation that occurs on some ocean shoresTessellated pavement

CEE 320 Spring 2007 Outline 1.Pavement Purpose 2.Pavement Significance 3.Pavement Condition 4.Pavement Types a.Flexible b.Rigid 5.Pavement Design 6.Example

CEE 320 Spring 2007 Pavement Purpose Load support Smoothness Drainage All weather operation Direction and guidance DC to Richmond Road in 1919 – from the Asphalt Institute

CEE 320 Spring 2007 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

CEE 320 Spring 2007 Interstate Highway System

CEE 320 Spring 2007 Interstate Highway System Largest highway system in the world Largest public works project in history Started construction in % federal, 10% state funding Owned built and operated by states Construction and maintenance costs primarily provided by fuel tax

CEE 320 Spring 2007 Resources Pavement Interactive State DOTs AASHTO

CEE 320 Spring 2007 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

CEE 320 Spring 2007 What makes it difficult Construction process control Material variations Exposed environment –Temperature and weather variability Transportation of materials Cost of materials Unkown traffic loads

CEE 320 Spring 2007 Pavement Types Flexible pavements –Asphalt Rigid pavements –Concrete

CEE 320 Spring 2007 Pavement Types Want to distribute the load to avoid permanent deformation

CEE 320 Spring 2007 Vehicle loads Typical vehicle weighs about 3500 lb, tire pressures around 35 lb/in 2 Truck can weigh up to 80,000 lb with tire pressure of 100 lb/in 2 Trucks and busses present a much more significant load on the pavement.

CEE 320 Spring 2007 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.

CEE 320 Spring 2007 Pavement Condition

CEE 320 Spring 2007 Pavement Condition

CEE 320 Spring 2007 Pavement Condition

CEE 320 Spring 2007 Pavement Condition Defined by users (drivers) Develop methods to relate physical attributes to driver ratings Result is usually a numerical scale

CEE 320 Spring 2007 Serviceability Concept Pavements degrade over time due to –Exposure to traffic –Time –Exposure to elements Different for different materials and different construction methods

CEE 320 Spring 2007 What pavement thickness is required to sustain X vehicle loads of Y weight?

CEE 320 Spring 2007 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

CEE 320 Spring 2007 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.

CEE 320 Spring 2007 Flexible Pavement Structure –Surface course (waterproof, anti-skid) –Base course –Subbase course –Subgrade

CEE 320 Spring 2007 Types of Flexible Pavement Dense-graded Open-gradedGap-graded

CEE 320 Spring 2007 Rigid Pavement

CEE 320 Spring 2007 Rigid Pavement Structure –Surface course –Base course –Subbase course –Subgrade

CEE 320 Spring 2007 Types of Rigid Pavement Jointed Plain Concrete Pavement (JPCP) Joints accommodate shrinkage during drying.

CEE 320 Spring 2007 Types of Rigid Pavement Continuously Reinforced Concrete Pavement (CRCP) Photo from the Concrete Reinforcing Steel Institute