lec 28 Flashcards
asphalt is visco elastic and thermoplastics materials ->
properties depend on rate of loading and temp
asphalt binders are usually soft at ___ temps and
soft at high temps and brittle at low temps
to properly study asphalt you need to consider what four types of behavior
high service temp (summer)
low service temp (winter)
average service temp
high temp (construction)
the average temp of pavement is typically considered to be
25C
the max temp of pavement typically is
60C
max spraying pumping mixing temp
135C
as[halt properties depend on
REFINERY OPERATIONS
COMPOSITIOB CRUDE SOURCE DEPENDANT
->purity
safety
cohesion
adhesion
CONSISTENCY
WORKABILITY
DURABILITY
if an asphalt binder is heated to a high enough temp it gives off sufficient…
vapors to flash (ignite in the presence of a spark or open flame
asphalt tests
I - pentration test
II -viscosity test
III - rotational voisocmeter
in pentration test
there is standard needle, specified load time and temp, we see how it penetrates (kinky)
80/100 penetration grade will have a penetrayion range of
8 to 10 mm
visocity is simply a measure of
the fluids resistance to flow
viscosity =
shear stress/shear rate
dynamic viscoty of water at 20C
0.001 Pa*s = 0.01 poise = 1 centipoise
the viscosity of asphalt binder at high manufacturing and construction temerpatures important because
it can control
pumpability
mixability
workavility
the specific gravity of asphalt is useful for
volumentric conversion in bituminous mix design
when buying asphalts what temp is standrad for properties measureing
27C
the spec gravity of pure bitumen ranges from
0.97-1.03
asphalt durability is a measure of how
asphalt binder physical properties changes with age
as asphalt ages it
gets more viscouse more stiff and more brittle
oxidization in pavement be like
the raction of oxygen with the assfault binder
volatalization (what is it bruv)
the evaporation of the lighter constituents of asphalt binder, it is primarily a function of temp and occurs principallyu during HMA production
polymerization
the combining of like molecules to form larger molucules, these larger molucues are thought to cause a progressive hardening (my dick)
penetration decreses with
aging (why old couples have less sex)
