Here in Waterloo we ran a test between "virgin" hot mix and hot mix
made with recycled tear-off and manufacture recycled shingles.
The same PG58-28 binder was used to prepare three
different mixtures: 20%RAP, 15%RAP + 5%
tearoff shingles, and 15%RAP + 5% manufacture waste shingles. The
results indicated that the two types of shingles perform differently.
The manufactured material seems to be beneficial, as it slightly
increases the stiffness and did not affect the tensile strength of both
mixtures and extracted binders. The binder critical temperature
increased very little. The addition of tear off shingles appeared to
affect properties in a more negative way, although it also increased
only slightly the stiffness of the binders. However, it lowered the
strength of the binder significantly at the higher test temperature
and increased the binder critical temperature. This was not
confirmed by the strength tests on mixtures, which did not indicate
any significant reduction with the addition of tear off shingles.
The extracted binder rheological data showed that the addition of
shingles increases only slightly the stiffness but lowers the
mvalues significantly. This indicates that the addition of shingles
lowers the temperature susceptibility of the binders making them
stiffer than conventional and RAP modified binders at intermediate
temperatures more characteristic of fatigue cracking distress.
It was explained that there were things that need to be
accounted for that those outside the industry do not look at.
For instance. As far as coatings used on a tearoff roof. The company
mixing the asphalt is responsible for the environmental impact of their
product. It is hard to accept that responsibility when you have
no way of knowing what coatings or adhesives were used
throughout the life of the roof. Then there is the properties of the
paper or any underlay whoever put the roof on used. When
all of the fish start dying from run off on the road heads will roll.
Most companies do not like dealing with unknowns when they
themselves have to accept total responsibility for any impact.
I am not a roofer or a asphalt guy. This is just information I gleaned
from my vast information network of people that are much
smarter than I am and talk way above my head. Basically what I
got out of our conversation and email was that there was a S#*t load
of homework and research for me to do if I were ever to think about
recycling shingles as ScrapperRick is talking about in this thread.
Sorry for the long techno babble my buddy sent me...lol
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