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RE: Lean concrete as structural fill?

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Thank you to everyone for the very informative
responses.  They were just what I was hoping for.

Jim Wilson

--- "Sherman, William" <ShermanWC(--nospam--at)cdm.com> wrote:

> ACI 116R, Cement and Concrete Terminology, defines
> "lean concrete" as
> "concrete of low cement content" and defines
> "controlled low strength
> materials" as "materials that result in a
> compressive strength of 1200
> psi or less".  As others have noted, "controlled low
> strength material"
> seems to be the preferred term for what is also
> called "flowable fill".
> 
> 
> I tend to think of lean concrete as concrete with a
> 28-day compressive
> strength of less than 3000 psi but probably greater
> than 1200 psi, i.e.
> just a relatively weak concrete due to the low
> cement content.  I would
> expect "lean concrete" to have a "normal" slump
> range vs flowable fill.
> I have used flowable fill/ controlled low strength
> material as fill
> material, with admixtures to improve flowability and
> resulting in the
> 300 psi compressive strength range.  
> 
> Either can be used, depending upon your strength and
> flow expectations. 
> 
> William C. Sherman, PE 
> (Bill Sherman) 
> CDM, Denver, CO
> Phone: 303-298-1311
> Fax: 303-293-8236
> email: shermanwc(--nospam--at)cdm.com
>  
> 
> > -----Original Message-----
> > From: Jim Wilson
> [mailto:wilsonengineers(--nospam--at)yahoo.com] 
> > Sent: Wednesday, July 06, 2005 1:29 PM
> > To: seaint(--nospam--at)seaint.org
> > Subject: Lean concrete as structural fill?
> > 
> > We are working with a contractor who has asked to
> use lean 
> > concrete as structural fill under footings and
> slabs for a 
> > single story building.  Through google searches,
> I've come up 
> > with matches to lean concrete, cement bound
> material (CBM) 
> > and flowable backfill. 
> > Are these all essentially the same product?  They
> don't 
> > appear to be well defined in terms of material
> properties, 
> > though I found one reference to 500psi minimum
> strength.  The 
> > flowable fill I have worked with in the past was
> 700psi. 
> > Also, these products are only mentioned in the
> context as 
> > being used for roadway sub-bases.  I'm guessing
> they are not 
> > commonly used in building construction because
> they are 
> > relatively costly compared to gravel backfills.
> > 
> > By comparison to regular gravels, this seems very
> acceptable 
> > as structural fill, but I'm looking for a second
> opinion.  
> > And is there an appropriate spec or even a product
> name to 
> > call this material for building use?
> > 
> > Regards,
> > Jim Wilson, PE
> > Stroudbsurg, PA
> 
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