Parkways and park roads :: :: University of Virginia Library

MIXES:

Road mix is bituminous concrete prepared with a patrol grader
and a spray rig alongside the road; cold mix is prepared in a plant
and spread and compacted at air temperature; hot mix is prepared in
a plant where oil and aggregate are heated before being hauled hot
to the job.

Oil (Bitumen) becomes more viscous with higher air temperatures;
at Death Valley with temperatures of 120+, oil runs like water and
must be blotted-up with sand! At Furnace Creek, the road oil flowed
to the bottom of a vertical sag in the road to the maintenance and
housing area. Try to explain that to the mothers and the school
teacher who stop by the job with fire in their eyes!

Write to the Asphalt Institute and the Portland Cement Association
for their publications. And send for a publications list
from AASHTO. Start your library now...it's a long time building!

BITUMINOUS MATERIALS:

1.

Requires soils analysis to determine thickness of pavement.

2.

Asphalt Institute establishes various thickness and spec for
soils.

3.

Low Type Bituminous: for wheel loads up to 7000 pounds; life
up to two years; requires annual seal coat; low cost, high
maintenance; surface treatment less than 1″ thickness;
"prime and seal coat: Armor coat"

4.

Calculate thickness according to Seelye table for "design of
flexible pavements"; design curves are by Asphalt Institute;
soils are classified by USDA or USCE

5.

Selection of Bituminous Material depends largely on temperature!

RT-1 is 60° to 125°	(RT = Road Tar)
RT-12 is 175° to 250°
RTCB is 60° to 120°	(RTCB = Road Tar Cut Back)
SC-0 is 50° to 120°	(SC = Slow Curing Road Oil)
SC-6 is 400° to 400°
MC-0 is 50° to 150°	(MC = Medium Curing Cut Back Asphalt)
MC-5 is 200° to 275°
RC-0 is 60° to 125°	(RC = Rapid Curing Cut Back Asphalt)
RC-5 is 200° to 250°
SS-1&2 is 50° to 120°	(SS = Slow Setting Asphalt Emulsion, AE)
MS-1 is 60° to 120°	(MS = Medium Setting Asphalt Emulsion, AE)
RS-1 is 80° to 135°	(RS = Rapid Setting Asphalt Emulsion, AE)

Asphalt Cement Penetration is hot application from 275° to 400°
(the higher the number the more viscous the material)

6.

Types of Pavement:

Type 1		Open type pavement, penetrating macadam, hot or cold, plant mix or road mix of crushed stone and bitumen (coated aggregate)
Type 2		Dense Mats, mixed in place, plant mix or road mix, aggregates graded coarse to flue and bitumen
Type 3		Dense graded pavement - Bituminous Concrete, plant mix of aggregates graded coarse to fine with minerals
Type 4		Dense graded sand pavements, Sheet Asphalt, Plant mix of sand passing #10 to #200 mesh, minerals
Type 5		Dense Sand Mat, Sand Asphalt, plant mix or mixed-in-place sand passing #4 mesh and bitumen