whats causing the block to deteriorate?
whats causing the block to deteriorate?
(OP)
see photo below for wall with one course of block deteriorating. any opinions on what is causing this?
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whats causing the block to deteriorate?
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whats causing the block to deteriorate?whats causing the block to deteriorate?(OP)
see photo below for wall with one course of block deteriorating. any opinions on what is causing this?
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RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
And i have seen many walls with efflor that are free standing, no soil; ie dumpster enclosures. Efflor, is not deterioration (we may just not be able to see the deterioration in the photo), it is the removal of salts/calcium from the block or water passing through the block.
RE: whats causing the block to deteriorate?
Other probable causes:
1. Incomplete application of a surface applied sealer
2. If the block has a waterproofing admixture (Prime-A-Pell or similar), it is possible for the admixture to be incompletely dispersed in the block, so you get odd patterns of efflorescence as a result
3. Variations in density of the block to allow variations in water intrusion, thus differences in efflorescence pattern.
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
1.) It is not deterioration, but a temporary surface deposit on the wall that can disappear with the weather or be cleaned of if i, but it is definitely not deterioration, it is not permanent unless it is fed moisture from a continuous source (like soil and standing water. Often, it a seasonal combination of weather conditions and exposures. Over time (many years), it can cause some surface deterioration.
2.) It has some benefits. When an engineer friend from a masonry group said, "It gives you clues to track down a basic problem with the structure". That was when we were looking (as a professional group) at exterior efflorescence on 4 story museum with a blue and white glazed brick exterior over concrete block. - It was in a full "bloom" when we were there. But at times, it was pristine and clean.
That indicated there was a lot of water in the exterior walls that was coming out. Nowhere in the interior of the museum was there any signs of moisture. It turned out the wall consisted of concrete block (partially grouted), no parging, but a black coating of some sort on the block and a small (3/8" maximum) gap to the brick to maintain a modular over-all wall thickness. Apparently, the weeps on the lower level of the wall could not handle the amount of water in the wall. Because of the pattern of the efflorescence, it became obvious there was water in the gap from a flashing problem on the roof, so the roofing and insulation had to be replaced. The brick was pressure washed and there were no more problems in the last 15 years or so.
I am not a fan or supporter of efflorescence, but it can be very helpful for diagnosis in some cases.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: whats causing the block to deteriorate?
there is no backfill or soil against either side of the wall, it is a freestanding wall anchored to a concrete foundation. no soil anywhere
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
The block might even be easy to scratch or gouge in the problem areas.
I'm wondering if the block manufacturing quality is just pretty crappy and inconsistent
RE: whats causing the block to deteriorate?
there is no soil in contact with the wall anywhere. what you see on the ground is just loose gravel over a mass concrete foundation
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
The "salts" in the concrete referred to do not swell or expand when wet. When the moisture, containing the salts, gets near to the surface, crystals form to cause expansion. - That is the same process for cast in place concrete. - Not that different from the pealing of paint with low permeability or multiple coats that just peel off because it has some tensile strength.
Some aggregates can cause problems because of their absorption and the ability to supply moisture. Some aggregates (like natural and manufactured lightweight aggregates) higher absorption but have a different structure and can absorb some of the forces from the external crystallization near there surface.
Dick
Engineer and international traveler interested in construction techniques, problems and proper design.
RE: whats causing the block to deteriorate?
There are other factors that bring in water other than by gravity via rain. Salts have affinity for water and the cement in the blocks may contain some. The white stuff shown is some form of salt(s). That affinity will "draw" moisture from the soil below by differences in vapor pressure's (caused by temperature differences, etc.) well as by capillary attraction. Moisture in the air also has been known to end up "wetting" salty areas. Such an example is the wet floor slab in my garage in spring where salty water earlier has dripped from the car in winter. That moisture came from the air probably, but see below.
This effect probably is similar to plastic floor covering systems (as in gymnasiums) which sometimes come loose with the mastic taking on moisture, sometimes blamed on that salt concentration remaining in the top of the slabs by drying some before the floor covering is placed. I've measured that and it is high in concentration at the top as compared to bottom of slab. Osmotic pressure differences come into play also. Yes, concrete makes a good osmotic "membrane". You remember that high school chemistry demo with the egg shell membrane? The pores in concrete work the same. These pressure differences can be quite high.
I won't say I have all the answers, but I have seen some real problems generally in this field. For instance explain how the bubbles in that gym flooring mastic contain water under pressure. If you measure that pressure, it is many inches of head above the floor. Certainly never got there by a water pipe breaking somewhere.
The efflorescence and deterioration of this post subject probably is related to those other problem factors with concrete mentioned.
Here is just one of the references one might look at on this subject.
http://www.foundationperformance.org/pastpresentat...
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
RE: whats causing the block to deteriorate?
Exactly cvg....
RE: whats causing the block to deteriorate?
http://www.finehomebuilding.com/how-to/articles/ho...
RE: whats causing the block to deteriorate?
I see lots of deteriorated CMU, and I'm used to seeing really crumbly faces - like being able to easily pop big chunks off with my awl. Can you do that here? Even sound CMU can be poked at occasionally.
Please remember: we're not all guys!
RE: whats causing the block to deteriorate?