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RE: Joints in retaining walls

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It is also not uncommon to find cracks at about 10-ft spacing in long walls of liquid-containing basins.  CRSI suggests that "the natural shrinkage crack interval" is on the order of 10 to 15-ft.  However, the cracks typically initiate at the base of wall, where it is restrained by the slab, and may not extend the full height of the wall. 
Such walls typically have extra horizontal reinforcing steel for crack control - the intent is to allow numerous fine cracks that don't leak but to control wider cracks.  This also improves appearance, since tight cracks are less noticeable.  Since the cracks initiate at the base slab, another technique is to double up the area of horizontal reinforcement near the base of wall to further control the cracks in this area.

William C. Sherman, PE
(Bill Sherman)
CDM, Denver, CO
Phone: 303-298-1311
Fax: 303-293-8236
email: shermanwc(--nospam--at)


From: Garner, Robert [mailto:rgarner(--nospam--at)]
Sent: Wednesday, March 22, 2006 8:22 AM
To: seaint(--nospam--at)
Subject: RE: Joints in retaining walls

I've seen this too.  I no longer put joints in my walls.  I just space the pvc sleeves for the railing at wherever I want a relief crack to appear.  I studied one such wall for a period after construction; the crack started at the sleeve at the top of the wall and over about a month, extended down the wall, nice and straight, pretty as any control joint.


Bob Garner


From: Ken Peoples [mailto:kspeoples(--nospam--at)]
Sent: Wednesday, March 22, 2006 4:41 AM
To: seaint(--nospam--at)
Subject: Re: Joints in retaining walls


I too have seen similar cracks at inserts - even at walls with joints.  I have often wondered whether it would be better to require core drilling for the railing posts and force the shrinkage to occur more at the joints. 


Best regards,


Kenneth S. Peoples, P. E.


Lehigh Valley Technical Associates, Inc.
1584 Weaversville Road
Northampton, PA 18067


Phone: 610-262-6345
Fax: 610-262-8188

----- Original Message -----

Sent: Tuesday, March 21, 2006 4:50 PM

Subject: Re: Joints in retaining walls


FWIW I once saw a cast concrete site retaining wall (i.e. not a building wall) somewhere in California, about 6' or 7' tall, with a fine, full-height vertical crack every 10', aligned with the inserts for a metal railing.  Not a "real" joint in sight!


In a message dated 3/21/06 1:41:03 PM, gloomis(--nospam--at) writes:

CRSI Design Handbook - Working Stress Design 1963 recommends contraction
joints at about 25' and expansion joints at every 4th joint - 100'.  The
newer CRSI 1996 states the same recommendations and also references
Figure 14-5 which is based on ACI 350.

Gary Loomis

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