Agreed that the microwave method is not always reliable although we use it
for student laboratory sessions where time is short and accuracy not
critical ( it provides a source of discussion!)
The 'moisture in the bag' technique (Greenwood and Norris, Ground
Engineering vol 32, 6, 32-33 (June 1999)) may help save some time on the
conventional oven moisture content determinations.
Regards
John Greenwood
Civil Engineering, School of Property and Construction
Nottingham Trent University
Burton St
Nottingham NG1 4BU
Tel 0115 848 2045, Fax 0115 848 6450
email [log in to unmask]
-----Original Message-----
From: Eric Parker [mailto:[log in to unmask]]
Sent: 08 March 2002 1:25 pm
To: [log in to unmask]
Subject: Re: Geotechnical Problems
Re question 1)
ASTM D4643 gives a method for moisture content by microwave. They suggest
about a 700W oven with variable power settings. The procedure is to heat
your sample for 3 min and weigh. Break up and mix the sample, re-heat for 1
min, weigh again. Repeat until you reach constant weight. Concerns are
overheating the sample yielding a higher water content than you would find
by the standard oven methods.
We tried this method offshore, but eventually abandoned as it was quite a
lot of work to do a good job on the heating and re weighing. If you have
time, standard oven drying is a lot easier.
Regards
Eric Parker
D'Appolonia
----- Original Message -----
From: "shbm msnbsh" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Friday, March 08, 2002 2:08 PM
Subject: Geotechnical Problems
> Hello everyone.
> I have few questions. I will start with the following
> one.
> 1) When conducting moisture content test on a soil
> sample, can microwave oven be used as an alternative
> to the normal oven? Actually the soil sample was
> placed in a 900 watt microwave oven for 5 minutes.
> Any comments on this procedure.
>
> 2) Can a slip circle failure occur within the
> embankment material itself? The embankment is 16m high
> with a 2m wide berm for every 6m. The embankment has
> an inclination of 45 degress (V:H, 1:1). The
> embankment has surface drainage.
> I understand that for fill slopes ( embankments) the
> mode of failure should be in the soft foundation,
> where the toe of the embankment will heave.
>
> 3) There is another case where the fill materail of
> the embankment is from mudstone origin. Actually the
> is a small stream (wet weathered stream) flowing
> underneath the embankment. I think the embankment
> should fail with time as the fine particles at the
> embankment toe are washed with the stream flow. Any
> comments on that?
>
> I wish someone could comment on the above posted
> issues.
> I had to post again as the first time I forget to put
> in the Subject.
> TQ.
>
>
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