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RE: Retaining wall of sawdust

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Thanks Lloyd for the info.  When I went to the site there was sawdust still 
 in the room and it was very dry.  It had the feeling of being kilned dried 
 which makes sense because they are taking this sawdust right into their 
hopper which then is pressed and turned into fire logs.  From my internet 
searching it seems like it is in the 5%-10% range.

Any idea how you would determine friction angle?  I may end up just using 
an E.F.P. which is around what I see around here for the local soils and 
call it a conservative design.



-----Original Message-----
From: seaint-seaosc(--nospam--at) [mailto:seaint-seaosc(--nospam--at)] On 
Behalf Of Lloyd Pack, P.E. Sent: Wednesday, May 13, 2015 1:03 PM
To: seaint-seaosc(--nospam--at)
Subject: Re: [SEAINT-SEAOSC] Retaining wall of sawdust

Hello Joe,

You say that the sawdust is protected so that it doesn't get wet, but what 
is the moisture content of that sawdust in the pile?  There are some species 
 of wood that will hold more that their dry unit weight in water. The amount 
 of water that a wood can hold is also dependent on where in the log the 
wood is located, or what type of wood it is.

For instance, Western Red Cedar, a commonly used wood for fences, has an 
average green moisture content of 58% for the heartwood and 249% for the 
sapwood.  The sapwood will hold quite a bit more water than the heartwood. 
Also the amount of heartwood or sapwood as a percentage of the volume of the 
 log varies quite a bit by species.

You need to find what the maximum moisture content is in the pile. Then you 
 will need to know the friction angle of the material in that pile.  I would 
 expect the friction angle to go up with an increasing moisture content. 
That is to say that the sawdust will be more prone to caking or adhering to 
itself with more moisture in the pile.  That will help with the lateral 
bearing pressure.  It may be that as the moisture goes up the friction angle 

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