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RE: Lightweight yet stiff fill ?

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Arvel –

 

90 PCF isn’t that much lighter than lightweight concrete. Can you think of anything lighter?

 

Thanks.

 

T. William (Bill) Allen, S.E. (CA #2607)

ALLEN DESIGNS

Consulting Structural Engineers

http://www.AllenDesigns.com

V (949) 248-8588

F (949) 209-2509

 

-----Original Message-----
From: Arvel L. Williams, P.E. [mailto:awilliams(--nospam--at)gwsquared.com]
Sent: Thursday, May 12, 2005 10:50 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Lightweight yet stiff fill ?

 

Bill,

 

Try some foam blocks from Contech.  Seen it used on airports over really bad subsurface soil condition.

 

Another alternative is pumice or expanded shale.  The unit weight is in the 90s pcf.  Might be expensive either way.

 

Arvel

-----Original Message-----
From: Bill Allen, S.E. [mailto:T.W.Allen(--nospam--at)cox.net]
Sent: Thursday, May 12, 2005 12:24 PM
To: seaint(--nospam--at)seaint.org
Subject: Lightweight yet stiff fill ?

I am working on a project where there is going to be an addition to an existing penthouse. The existing roof is concrete slab over metal joists. The new slab will be at least 6 inches above the existing roof slab and may be as much as 12 inches above at the low part of the roof. Due to the loading, I don’t want to fill the entire space with concrete. I would rather use a thin slab (4” lightweight; 3,000 psi w/#3 @ 15” E.W. or something close to that) over some lightweight material. My concern is the stiffness, of course. The use is residential, so there will not be any heavy loads on the slab, but I do not want the slab to “settle” too much. My first thought was pearlite or vermiculite, but I don’t know if either is stiff enough.

 

Any thoughts/recommendations would be appreciated.

 

T. William (Bill) Allen, S.E. (CA #2607)

ALLEN DESIGNS

Consulting Structural Engineers

http://www.AllenDesigns.com

V (949) 248-8588

F (949) 209-2509