Need a book? Engineering books recommendations...

Return to index: [Subject] [Thread] [Date] [Author]

RE: Crumbling concrete

[Subject Prev][Subject Next][Thread Prev][Thread Next]
Since it is 100 years old I would consider it may have been site mixed
by hand.  I have been on trips to Mexico and other 3rd world countries
where this is still common today.  The sandy soil is piled up and cement
added and then a bunch of guys attack it with shovels.  Dirt gets mixed
is and the aggregate is not always clean to begin with.  It is placed by
buckets.

Just a thought.

Rich Lewis
Lewis Engineering


-----Original Message-----
From: Jordan Truesdell, PE [mailto:seaint(--nospam--at)truesdellengineering.com] 
Sent: Thursday, December 23, 2004 8:19 AM
To: seaint(--nospam--at)seaint.org
Subject: Crumbling concrete

I'm curious what would cause older concrete walls to crumble into a 
lightweight, easily-friable condition.

Here's my story:

I just went by a 100+/- year old residence yesterday and saw the most 
amazing concrete wall deterioration I've ever seen.  Portions of this 
mostly-above-ground basement wall (I'm going to say 30-50%) were friable
to 
the touch, and easily (literally fell apart) crumbled in my hand.  In
the 
soft areas, a masonry bit advanced without significant resistance until
it 
hit a large piece of aggregate, usually about 1.5 to 2" into the 9"
thick 
wall. My only time reference is that - according to the owner - it
wasn't 
present in the 60s when they bought the place.

There is significant evidence that some organics were included in the
mix, 
along with sand and round river rocks.  You can see the diagonal
striations 
of segregation from where the concrete batch placement started at the 
corners and flowed down the walls to its final resting place.  I'm
guessing 
that casual water intrusion has slowly decayed the organics to the point

that they have partially disintegrated reducing the strength, with the 
remaining organics moisture cycling to break what was left.  There was
no 
obvious sign of chemical residue on the surface of the wall.

Interestingly, there is no sign of macro-deterioration of the structure 
(yet). No settlement or stress cracks, even where the unbalanced
backfill 
is close to 5 feet.  Nonetheless, the walls are going to have to be
replaced.

I'm curious what might be happening, and if there are any tests that
might 
be recommended to determine the cause of the damage.  I'm doing this as
a 
side research (unbillable) for future reference, as the current owner
just 
wants to know how to fix the problem (replace the walls), and the value
of 
the house is only about $120k-$130 without the wall issue, and currently

has no historic significance.

If you're curious, there are some photos here:

http://www.truesdellengineering.com/1125/index.html

Thanks, in advance, for any thoughts/suggestions you folks might have,

Jordan



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ******** 



******* ****** ******* ******** ******* ******* ******* ***
*   Read list FAQ at: http://www.seaint.org/list_FAQ.asp
* 
*   This email was sent to you via Structural Engineers 
*   Association of Southern California (SEAOSC) server. To 
*   subscribe (no fee) or UnSubscribe, please go to:
*
*   http://www.seaint.org/sealist1.asp
*
*   Questions to seaint-ad(--nospam--at)seaint.org. Remember, any email you 
*   send to the list is public domain and may be re-posted 
*   without your permission. Make sure you visit our web 
*   site at: http://www.seaint.org 
******* ****** ****** ****** ******* ****** ****** ********