Construction & quality

Highway Materials, Construction and Quality

CEE 483

• $ 1.5 trillion or ~ 17% of GDP • ~ 12 % of U.S. Employment • 50 miles per day per person

Importance of Transportation

• Miles of Roadway: • Interstate: 46,000+ • National Hwy System: 66,500 • All Other Paved: 2,282,000 • Unpaved: 1,479,000 • Annual investment: $18 + billion

Importance of Pavements

• Pavement roughness increases vehicle component failures.

• Bad roads cost motorists $$$ billions annually in repair and operating costs.

• Trucks use 4.5% less fuel on smooth pavements than on rough.

Other Important Facts on Pavements

Annual HMA Investment

• $15 Billion

• 500 million tons of HMA

• 30 million tons of liquid binder

Design Struct Geom

PAVEMENTS

Construction

Materials

ManagementEvaluation

Traffic

Transportation Systems

CEE 483 / 583

CEE 514, 515

CEE 513

412/511 - 475

CEE 474

CEE 512

-CEE 372

Mix Design

Structural Design

εt εc

εt εc

εt at surface + bottom of all bound layers (cracking) εc at midthickness of all layers + top of subgrade (rutting)

Subgrade Soil

Base/Subbase

Surface SUR

εSUB δSUR

Axle Load

ε

Construction

NDT Load

“Strong” Pavement “Weak”

Pavement ∆

NDT Sensors NDT Load

∆

r

Functional Performance

Gross Loads

HMA Pavements

• Review of Basics – Pavements types – Factors affecting performance – Distress and causes

• HMA – with unbound (granular) base – with bound (stabilized) base – full-depth HMA

• Composite – HMA over PCC

Types of HMA Pavements

Wearing Course Binder Course

Base Course (Bound or Unbound)

Subbase Course (Usually Unbound)

HMA Surface

Subgrade Soil

Hot Mix Asphalt HMA

• Structure:

What is the Role of Each Pavement Layer ?

HMA Layer

Base Course

Subbase Course

Subgrade Soil

4 Roles: Structural capacity

Frictional resistance

Smooth ride

Moisture barrier

Structural capacity Keep Moisture from beneath

Structural capacity

Functional / Structural Performance

Performance Indicator Functional Structural

Distress √ √

Structural Response √

Surface Friction √

Roughness √

Traffic Subgrade

Soil

Materials C&M Variation

Environment

M&R

PAVEMENT PERFORMANCE

Factors Affecting Pavement Performance

M&R

Pavement Performance

Time (Years)

Preventive Maint.

Routine Maint.

Defer Action Resurfacing

Reconstruction Pavement Condition

Good

Poor

Problems / Distresses

Subgrade Soil

Subbase

Base

HMA Surface

Wheel Load

Rutting Mechanism

Rutting

Wheel Load

Fatigue Cracking Mechanism

Fatigue Cracking

Location Along HMA Surface

Contraction HMA

Friction on Underside of HMA Surface

Tensile Stress

Crack or Cold Joint

Crack or Cold Joint

Surface

Tensile Strength

Thermal Cracking Mechanism

Transverse Cracking

200+ mm HMA

Surface

Oxidation Penetration Surface-Initiated Crack

Interface Between Lifts

Top-Down Cracking Mechanism

Separation of asphalt

binder from aggregate

Stripping Mechanism

Subbase Course

HMA Overlay

Subgrade Soil

PCC Slab Underlying Joint

Tension Shear

Wheel Load

Reflection Crack Mechanism

Potholes

Block Cracking

Raveling

Bleeding

Common HMA Distresses Distress

Type Traffic/ Load

Climate/ Materials

Fatigue Cracking Block Cracking Trans/Long Cracking Potholes Patch/Patch Deter. Rutting/Shoving Bleeding Weathering/Raveling

LTPP Distress Identification Manual

• Research-oriented • All pavement types • Distress definitions • Schematic drawings • Photographs • Data collection

forms

Schedule – Part 1: HMA HMA Mixtures Plant Operations Surface Preparation Mix Delivery HMA Placement Joint Construction Compaction QC/QA Troubleshooting