asphalt mixtures

Asphalt MixturesBy: Braden Watson

Introduction

What my company does.My experience with asphaltMy goals

History of asphaltAsphalt occurs naturally in both lakes and in rock asphalt.

History of AsphaltFirst recorded as a road building material around 625 BC in Babylon.Comes from the Greek word “asphaltos” meaning secure.Used by the Greeks and the Romans.Sir Walter Raleigh

First Asphalt RoadwaysTurnpikes in ScotlandAsphalt comes to America

Mainly used for sidewalks and crosswalks.

Roads started to be paved in the late 1860sEdmund J. DeSmedt laid the first asphalt road.

Paving in AmericaIn 1896, New York City adopted asphalt paving.

New York required a 15 year warranty.

Original PatentsThe first patent on Hot Mix Asphalt (HMA) was in 1871 by Nathan B. Abbott of Brooklyn, New York.Limited Technological growth.Original patents expired in 1920.

Changing TechniquesUntil 1900 almost all asphalt came form Trinidad Lake.Refined Petroleum Asphalts

Originally used as an additive.

Paving Operations

My ProjectI created an asphalt mix design for Asphalt Materials.I worked with

Asphalt Materials Inc. (Producer)Star Paving (Contractor)CMT Engineering (Designer/Quality Control)

My Project Time:

Design time: 50 hoursQuality Control: 20+ hours

Materials used:Sinclair 64-22 binderAMI AggregatesCMT’s asphalt laboratory

Marshall Mix Design6 basic steps:

Aggregate selectionAsphalt binder selectionSample PreparationStability determinationDensity and VoidsOptimum asphalt binder calculations

Aggregate SelectionDetermine aggregate physical properties:

Toughness and abrasionDurability and soundnessCleanlinessShape and surface textureGradation and size

Aggregate Blending

Must meet the specification for the job.Typical specifications require a certain percentage be retained on a particular sieve size by weight.

Asphalt Binder Evaluation

The Marshall mix design does not have a specific asphalt binder.Each entity has its own specification for binder usage:

UDOT 58-22UDOT 58-28APWA 64-22 (Also same as UDOT)

Optimum Asphalt Binder Content

This is specified in the mix design specifications by UDOT, APWA, or other city entities.

Sample PreparationSeveral trial aggregate-asphalt binder blends are created.Usually 5 different blends, 3 samples of eachSamples are prepared in 0.5 percent by weight increments.

Marshall CompactionAutomatic and manual versionsSpecified number of blows.Specifications for the machine.

Stability and FlowPerformance prediction measure.Measures the maximum load.Measure the specimens plastic flow as a result of the loading.

Density and Voids

Bulk specific gravityFinds the maximum density of the asphalt.

The specific gravity is used to calculate the Air Voids and the Voids in the Mineral Aggregate.

This is what you don’t want!

Stability: Recommended Oil Content:Flow: Virgin Oil Content:Air Voids: Lottman (TSR):VMA Oil Supplier/Grade:Anti-Strip: Bulk Unit Weight:

Max. Density (Rice): No. of Blows:

(inch) (mm)1 25

3/4" 191/2" 12.53/8" 9.5#4 4.75#8 2.36#16 1.18#30 0.6#50 0.3#100 0.15#200 0.075

33 28-4253

24

3-77.012

11-2318

60-8076

100

None 143.4

Job Mix Formula

88.4

Specification

94

100100100

100100

75

5.294900

RECOMMENDED DESIGN CRITERIA6.14

144.0

Sinclair PG 64-22

Percent Passing

15.2

2.389

ConclusionI have learned the basics of asphalt mix designs.My design was used on a couple of projects:

Wal-Mart on 10400 South and Bangerter Hwy.2 Walgreens

I have developed good relationships with everyone involved.Good technical understanding of asphalt.

Questions?