# Block Foundation - Bad Mortar Joints due to cold



## arik103 (Feb 18, 2014)

Hi,
I hired a sub to build a foundation. Foundation is build from 12" block.
Unfortunately we had VERY cold days here at night and he did not cover the new work with mats in 2 cold days.
It's been about 2 weeks since last blocks have been put in and now I able to peel thin outer layer of a mortar joint out in some spots. Also foundation was filled in every other block and in some spots I can peel sand out of cement that was put in.

Where do I go from here? 
If I parge on the inside will that help? Do I need to fill in the rest of the blocks?

Thanks,


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## pappagor (Jan 29, 2008)

blow it up


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## greg24k (May 19, 2007)

Post introduction and where you located?


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## concretemasonry (Dec 1, 2006)

arik-

You probably do not have structural problem based on the type of construction you described.

Mortar actually is a minor factor in the strength of a wall for vertical loads. The strength of the block controls and you would be hard pressed to find a block that does not meet specifications (most are 30% to 50% over specs. With the current manufacturing equipment and processes it actually costs more money to make a low strength block because it could not be handled economically.

For lateral loads, the arbitrary dumping grout into unreinforced cores is a waste of time and money. Some poor masons just use the open cores to get rid of old or dried mortar. Obviously, the cores with rebar must be filled with grout (NOT MORTAR) that is very wet (8" to 11" slump). and poured in lifts. The rebar is what does increase the lateral strength of a masonry wall. I have even seen specs that had a limit of the maximum strength of grout allowed.

Even cold mortar that freezes "dry" will cure it moisture is available and the temperature comes up a bit because of the lime in the mortar, bit it will not be as durable if it is exposed to the weather.


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## arik103 (Feb 18, 2014)

I am located in Northern NJ.

They did fill in every 2 blocks and reinforced with rebar. Not sure on exact size of rebar but it looked thinner that 1/2 inch that was used for footers. However they were mixing the grout on the same day they did mortar, so not sure how solid it is. They used send, lime, portland and very fine rocks to fill in the blocks.

Thanks all for your help. I will try to post some pics tomorrow.


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## greg24k (May 19, 2007)

The way this weather been here in Jersey in single digits, he should have covered his work with insulating blankets or provide some type of a equivalent protection for at least 24 hrs, especially when you have a structurally reinforced wall. 
In most cases involving structural masonry walls, etc. in detail notes on the drawings it would specify what have to be done when working in freezing weather.


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## CJKarl (Nov 21, 2006)

I think I might make him tear it out and rebuild it.


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## CJKarl (Nov 21, 2006)

What were the specs?


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## concretemasonry (Dec 1, 2006)

Specs on a 12" foundation (probably residential)? Lucky if there is something like reinforcement.

If there are specs, usually the price is higher and there is a reason for it.


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## arik103 (Feb 18, 2014)

This is residential construction. No specs.
Thanks all


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## fjn (Aug 17, 2011)

CJKarl said:


> I think I might make him tear it out and rebuild it.





:thumbsup:


To stack X amount of thousands of dollars on top of an iffy foundation does not make sense to me. Just my .02 cents.


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## NJ Brickie (Jan 31, 2009)

I'm with Dick on this. I do agree that this sounds like laziness and isn't good craftsmanship. But I doubt there is any structural issues to be worried about. The outside will be parged? What about the inside? Painted? 
I'd make them fix any bad joints inside and have a talk with him. Discuss your issues with his quality of work. And if there is any business future between the two of you.


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## dom-mas (Nov 26, 2011)

concretemasonry said:


> . Obviously, the cores with rebar must be filled with grout (NOT MORTAR) that is very wet (8" to 11" slump).


I've seen you write this a few times and I just can't understand why? Unless you mean just the consistency can't be like mortar. I have taken apart dozens of walls that have been grouted with wet type S, there is no aggregate beyond sand, and the wall is solid (often they have withstood severe vehicle impacts, the last one was a semi in a repair shop) , the grout is in good shape and making good contact between the rebar and the block...what else is necessary? All the grout needs to do is take up space and connect the rebar to the block. Wet, pourable mortar does this fine


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## arik103 (Feb 18, 2014)

The outside is parged already. Some parts will be covered with stone. 
I was thinking to parge the inside also, to prevent any sand from falling out.


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## superseal (Feb 4, 2009)

The grout will probably be okay, but the mortar joints have been compromised if they truly froze prior to initial cure. That thin, peeling layer you mentioned and sandy surface would make my hair stand on end and would require a more formal inspection to determine a course of action. 

Maybe saw-cutting a nice deep cut and re-pointing using the same mix is in order at the very least.


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## concretemasonry (Dec 1, 2006)

dom-mas -

I don't think some mortar with water to soup it up would be acceptable in any civilized country, but it might look OK until there is a real load on the wall (like a taller 8" block basement with wet soils). Water does not make it better, but helps it fill voids and does reduce the bond strength and transfer between the bars and masonry units below reasonable levels because the aggregate (fine sand only).

The reason engineers limit the strength of the grout to make sure the wall constructed is to perform as intended. Not a big deal on a basement, but the bad habits can cause problem of other types of buildings when people get in over their heads and use old habits. That is the reason for the minimum standards, codes and specifications.

Engineers can also get over their heads by adding to much in the wrong places. I saw that on a building after the Northridge, CA earthquake and subsequent tremors 2 days later. When it went down, it was evident the corners had far to much steel that was too stiff and took too much load, so the rest of the walls did not really get loaded until the corner sections failed. It all has to do with proper materials being used for a balanced design and construction.

Mortar is just different than grout. I have had 4800 psi(net area) f'm hollow prisms that were made with type N mortar because the mortar is a thin layer that is only and compression and never has much effect on shear. Grout is different because it has to work in all 3 dimensions.

arik 103 -

Since the interior is not parged, tuck pointing would help for surface density, eliminating sanding and final finishing. - If it was me, I would coat the interior with Thoroseal, since it is more compatible with the wall materials, but it is messy and more work than paint. It will accept many other different materials than paint will after the fact.


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## JBM (Mar 31, 2011)

The foundation will probably leak when the frozen mortar eventually pops out of place leaving places that arnt water tight.


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## fjn (Aug 17, 2011)

Some components of this thread remind me of a story I read many years ago. A few years after Frank Loyd Wright completed his famous "Falling Water" the large cantilevers started to develop cracks and started to sag. When Wright was confronted as to the reason why,he immediately pleaded innocent.He said it was all because the concrete contractor feeling there was an inadequate amount of rebar in them arbitrarily took it upon himself to add more steel. Wright stated, 'the weight of the extra rebar caused the cantilevers to sag " ! :laughing:


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## dom-mas (Nov 26, 2011)

concretemasonry said:


> dom-mas -
> 
> I don't think some mortar with water to soup it up would be acceptable in any civilized country, but it might look OK until there is a real load on the wall (like a taller 8" block basement with wet soils). Water does not make it better, but helps it fill voids and does reduce the bond strength and transfer between the bars and masonry units below reasonable levels because the aggregate (fine sand only).
> 
> ...


Not much of an answer to me. The difference between grout and mortar is consistency and purpose. The only purpose of the grout is to fill the void and allow the rebar and the block to work together. 

The project i was just talking about where the semi hit the wall, was a 18' tall 10" block wall. the reinforced cells did their job and there was no major catastrophe. A few blocks were smashed, but the roof didn't come down, and the rest of the wall was left intact.

On small jobs where it is inconvenient to get a pumper in, soupy type S has been used countless times and has worked just fine. The only limits I have seen for grout were maximiums for aggregate, which sand doesn't pass, and minimums for strength, which Type S satisfies.

I just don't buy what you're selling, but i guess me and my compatriots are just uncivilsed


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## concretemasonry (Dec 1, 2006)

Dom mas -

Sorry you don't agree with the rest of the world, but your jobs may be different.

I will pass your ideas on to the code and ASTM standards committees at the next meetings that set the standards including your methods and opinions. These committes are generally consensus committed that have a balance of contractors, users, suppliers and interested parties.

Some places, the contractors are little more progressive and they know how to get approval to build high rise loadbearing building without clean-outs because they use our codes and use TV camera to spot check that the cores are clean. If the workmanship is not good enough, the walls are torn down and the rate of inspection is increased - in Brazil.

I am not selling anything other that good masonry structures.


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