SUPERPAVE Digest 228
Topics covered in this issue include:
1) Odp: Tests for SMA Mix
by "=?iso-8859-2?Q?Krzysztof_B=B3a=BFejowski?=" <krisbi@kabatnet.waw.pl>
2) Re: Odp: Tests for SMA Mix
by khobson@fd9ns01.okladot.state.ok.us
3) Re: Change of E-mail address
by Tom Reese <prentex@iamerica.net>
4) Tests for SMA Mix - Schellenberg method
by "=?iso-8859-2?Q?Krzysztof_B=B3a=BFejowski?=" <krisbi@kabatnet.waw.pl>
>Could anyone please help me proving info on the following tests and testing
>procedure for SMA mix:
> b) Binder Drain-off Test
In Europe we use for SMA binder drain-off test well known the Schellenberg
method. It is German method.
Sample of hot SMA mix (1 kg) in 2 litre glass beaker is putting into oven at
170 Celsius for 1 hour. After taking out from oven hot SMA is poured out.
Then beaker is weighted. The mass of SMA mix which remain inside the beaker
is recalculated as a percent of initial sample mass (1 kg). Depending on
results you have to use the fibres (more or less) or not.
Regards
Krzysztof BLAZEJOWSKI
Engineering Bureau, Warsaw, Poland
krisbi@kabatnet.waw.pl
>In Europe we use for SMA binder drain-off test well known the Schellenberg
method. It is German method.
>Sample of hot SMA mix (1 kg) in 2 litre glass beaker is putting into oven at
170 Celsius for 1 hour. After taking out from oven hot SMA is poured out.
Then beaker is weighted. The mass of SMA mix which remain inside the beaker
is recalculated as a percent of initial sample mass (1 kg). Depending on
results you have to use the fibres (more or less) or not.
What percentage are you looking for? I wonder though that a more "sticky"
asphalt would give an incorrect percentage since more aggregates would adhere to
the beaker. Do your maximum limits for percentage retained in beaker vary for
different SMA's and asphalt cements? What grades of asphalt cement do you use?
At what stage in the SMA design do you run this test?
Since SMA's started in Germany and have been used in Europe for many years you
should know it best.
Kenneth Hobson
Engineering Manager
OKDOT Bituminous Branch
405-522-4918
405-544-0552 fax
khobson@odot.org
Joseph
THe correct address to send changes in you list characteristics to is:
<listproc@lists.cc.utexas.edu>
I forwarded you request to that address.
Josiah Yuen wrote:
> Dear Newsgroup Administrator,
>
> This is to notify you that my e-mail address has change from:
>
> jyuen@mailgw.dot.state.tx.us
>
> to :
>
> josiah@technologist.com
>
> Starting today's date, please have all future e-mails forwarded to my new address, thank you!
>>In Europe we use for SMA binder drain-off test well known the Schellenberg
>method. It is German method.
>>Sample of hot SMA mix (1 kg) in 2 litre glass beaker is putting into oven
at
>170 Celsius for 1 hour. After taking out from oven hot SMA is poured out.
>Then beaker is weighted. The mass of SMA mix which remain inside the beaker
>is recalculated as a percent of initial sample mass (1 kg). Depending on
>results you have to use the fibres (more or less) or not.
>
>What percentage are you looking for? I wonder though that a more "sticky"
>asphalt would give an incorrect percentage since more aggregates would
adhere to
>the beaker. Do your maximum limits for percentage retained in beaker vary
for
>different SMA's and asphalt cements? What grades of asphalt cement do you
use?
I use following criterion:
<0.1% mass - very good
0.1-0.2% still acceptable
>0.3% bad, one has to change amount of stabiliser (fibres) or change in
mineral mix.
For SMA we use asphalt cements with penetration @25C: 50/70 or PMBs (similar
pen grade). As a stabiliser we most often use cellulose fibres in amount
0.3% by mass of SMA mix (ie 3 kg fibres per 1 tonne SMA). Limitations are
from 0.15 till 1.5% fibres in SMA.
I said most often 0.3% but for new SMA we prepare in laboratory series of
SMA mix samples (of course without compaction) for Schellenberg test with
different amount of stabilisers. For different drain-off results one can
draw a chart of stabiliser efficiency and choose right content.
It is true that more "sticky" asphalt would give sometimes incorrect
results. Problem of "sticky" asphalt means problem with asphalt viscosity at
test temperature. It would occurs when use a PMB with high content of
polymer (ie SBS or SIS block copolymer). In this case you can raise test
temperature up to 180 C. The main rule is: SMA mix should be tested at the
highest temperature which can occurs during productions. Usually at this
temperature asphalt is enough liquid for coating the aggregate and -
unfortunately - drain-off. Test time (1h) is simulation of SMA storage time
in silo.
>At what stage in the SMA design do you run this test?
We do it at the end of design process after checking mechanical and physical
properties.
P.S. The beaker is not 2 litre but 0.8 litre (dia 9.8 cm and high 13.6 cm).
Sorry for mistake.
Regards
Krzysztof BLAZEJOWSKI
Engineering Bureau, Warsaw, Poland
krisbi@kabatnet.waw.pl
