History of Mn/DOT HMA Mixture Design & Construction

Significant Changes

By: Dave Holt,

Dick Ingberg, and

Earl Angell

1950’s

• Transition from Road-Mix to Hot-Mix

• Density Control

Roadmix

HMA Plant

Hveem Compactor & Heavy Pnuematic Roller

1960’s• Elimination of Hot Screening

• Mix Design for Surface Coarse

• Thin HMA Overlays/Plant-Mix Seals

Screen Deck & Drum-Mix Plants

CWA Test

Thin Overlay

1970’s• Oil Embargo

• Drum-Mix Plants

• Hot-mix Recycle

• Full-Depth HMA Design

Avg. AC Bid Price, by Mn/DOT

0

50

100

150

200

Year

Cos

t/Ton

(D

olla

rs)

Black Base Consumption, by Mn/DOT

0

0.2

0.4

0.6

0.8

119

67

1968

1969

1970

1971

1972

1973

1974

1975

1976

1977

1978

1979

1980

1981

Year

Ton

s of

Bla

ck B

ase

(Mill

ions

)

HMA Recycling

HMA Recycling

HMA Recycling

1980’s• Q/M (Quality Management)

• Volumetric Training

Training & Voids Testing

1990’s• Certified Technicians

• VMA & Moisture Susceptibility

• SuperPave

Technicians Certified per Year

0

1000

2000

3000

4000

5000

Tec

hnic

ians

Bit Street 1

Bit Street II

Bit Plant I

Bit Plant II

Immersion/Compression TestSuperpave Gyratory Compactor

2000’s

• Warranties

• Design/Build

Percent of Pavements Rehabilitated(Joint Repair for Concrete or Overlay for Bituminous)

0%

20%

40%

60%

80%

100%

0 10 20 30 40 50

Pavement Age, years

Per

cen

t R

ehab

ilit

ated

Pcc

AC