Asphalt Mixtures

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Asphalt Mixtures. By: Braden Watson. Introduction. What my company does. My experience with asphalt My goals. History of asphalt. Asphalt occurs naturally in both lakes and in rock asphalt. History of Asphalt. First recorded as a road building material around 625 BC in Babylon. - PowerPoint PPT Presentation

Text of Asphalt Mixtures

Asphalt Mixtures

Asphalt MixturesBy: Braden Watson1IntroductionWhat my company does.My experience with asphaltMy goals

2History of asphaltAsphalt occurs naturally in both lakes and in rock asphalt.

Rock asphalt is a combination of sand, limestone, and asphalt.In the photo, this is Lake Trinidad, located just outside the city of Trinidad. This is one of the largest natural asphalt lakes in the world. Lasco; UK based company owns the lake and produces pipe sealants, brick paint, and automotive under sealants.

3History 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

Oil was mixed with rock to form asphalt in front of temples.Used by the Romans to seal their baths, reservoirs, and aqueducts.Sir Walter Raleigh wrote about a lake of asphalt on the Island of Trinidad off the coast of Venezuela. He used it to re-caulk his ships.

4First Asphalt RoadwaysTurnpikes in ScotlandAsphalt comes to AmericaMainly used for sidewalks and crosswalks.Roads started to be paved in the late 1860sEdmund J. DeSmedt laid the first asphalt road.

Some of the first asphalt roads were turnpikes in Scotland. They were made up of broken up rock and hot tar. The main purpose was to keep the dust down. The idea was from the self-taught engineer John Loudon McAdams.Where was the first asphalt road paved?In front of the city hall in Newark, New Jersey. The design came from a design used on a French Highway in 1852.DeSmedt went on to pave Pennsylvania Ave. in Washington DC. It took 54,000 square yards of sheet asphalt from Trinidad Lake.

5Paving in AmericaIn 1896, New York City adopted asphalt paving.New York required a 15 year warranty.

New York adopted asphalt paving over brick, granite, and wood blocks.The 15 year warranty put many contractors out of business. Also no one would bid on work in New York.6Original 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.Asphalt technology did not advance between 1871-1920. After the original patents expired Federal and State engineers went to work on improving asphalt.7Changing TechniquesUntil 1900 almost all asphalt came form Trinidad Lake.Refined Petroleum AsphaltsOriginally used as an additive.Refined petroleum asphalt was originally used to thin out the thick natural asphalt. This material started to gain acceptance and in 1907 refined asphalt products were used more than natural asphalt.8

9Paving Operations

Paving operations consisted of broken rock in metal pans. The contractor would the pour hot asphalt on top and mix until the correct consistency was achieved. This took a lot of skill, this was also the cause of some poorly laid roads.Discuss current paving operations.

10My ProjectI created an asphalt mix design for Asphalt Materials.I worked with Asphalt Materials Inc. (Producer)Star Paving (Contractor)CMT Engineering (Designer/Quality Control)

11My Project Time:Design time: 50 hoursQuality Control: 20+ hours

Materials used:Sinclair 64-22 binderAMI AggregatesCMTs asphalt laboratory12Marshall Mix Design6 basic steps:Aggregate selectionAsphalt binder selectionSample PreparationStability determinationDensity and VoidsOptimum asphalt binder calculations

13Aggregate SelectionDetermine aggregate physical properties:Toughness and abrasionDurability and soundnessCleanlinessShape and surface textureGradation and size

What do you think is important when selecting aggregates?Porous or slightly porous.Fracture faces (UDOT requires 80% Fractured rock)Wear (Will the aggregate hold up to compaction methods?)Clean vs. Dirty aggregate/sand. 14Aggregate BlendingMust meet the specification for the job.Typical specifications require a certain percentage be retained on a particular sieve size by weight.

UDOT and APWA have their own specifications for aggregate blends.Often more than one stockpile is used to obtain the final aggregate blend. Many trial blends are done. Usually more 2-3 are saved or use in the mix design. Depending on what the customer wants.15Asphalt Binder EvaluationThe 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)16Optimum Asphalt Binder ContentThis is specified in the mix design specifications by UDOT, APWA, or other city entities.17Sample 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.

2 samples above optimum, 1 at optimum, and 2 below optimum.18Marshall Compaction

Automatic and manual versionsSpecified number of blows.Specifications for the machine.Sample size = 102 mm (4-inch) diameter cylinder 64 mm (2.5 inches) in height (corrections can be made for different sample heights)Tamper foot = Flat and circular with a diameter of 98.4 mm (3.875 inches) corresponding to an area of 76 cm2 (11.8 in2).Compaction pressure = Specified as a 457.2 mm (18 inches) free fall drop distance of a hammer assembly with a 4536 g (10 lb.) sliding weight.Number of blows = Typically 35, 50 or 75 on each side depending upon anticipated traffic loading.Simulation method = The tamper foot strikes the sample on the top and covers almost the entire sample top area. After a specified number of blows, the sample is turned over and the procedure repeated.

19Stability and FlowPerformance prediction measure.Measures the maximum load.Measure the specimens plastic flow as a result of the loading.

Loading rate is 2 in/min. It is increased until the asphalt breaks.20Density and VoidsBulk 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.Air voids and VMA is specified in the job specifications.21This is what you dont want!

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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 WalgreensI have developed good relationships with everyone involved.Good technical understanding of asphalt.24Questions?25