How to tell if a concrete block wall has been frozen

[SperlingPE]

I am looking at pictures of a concrete block wall that is going up in a cold climate. There is a purple/pink hue on the face of the block. Any idea as to what this might be?
I have not seen the wall in person, yet. So I have no other information.

 

[jike]

I do not know what the purple color is. When mortar freezes, it turns to a powdery substance.

In our area (currently minus 14 degrees and contractors not working today) they would generally use a movable, heated scaffolding. Alot of them refer to it as a "Morgan".

 

[JStructsteel]

can you upload the pics for us to see...Did they use any admixtures in the grout?

 

[SperlingPE]

All protection issues aside (protecting block from cold temperatures), I am thinking that this is an admixture that leached out or a salt that leached out. I was always told that frozen block walls turn a greenish color. The walls are grouted.

 

[Ron]

Pattern is not uniform and occurs sporadically. How were the blocks stored? Is it coincidence that the color of the scaffold boards is similar to the stain on the block?

It is not from freezing. Freezing of the block would result in some spalling/cracking assuming enough water were present to expand. Freezing mortar would show as someone noted, friable.

While it could be an admixture, it is too sporadic assuming that similar batches of block production are represented, thought it could be isolated to a run of blocks, since it does seem to occur in groups of placement (possibly from same pallet?)

No solution, just things to ponder.

 

[hokie66]

I have seen similar colouration in walls in hot climate conditions, so don't think it is because of freezing.

 

[LobstaEata]

Could be that some of the block have been purchased from different manufacturers or if from a single manufacturer, perhaps they were cast in separate lots using sand with dissimilar color characteristics.

 

[apriley]

It could be graffiti that has been removed.

 

[civilperson]

The color of the blocks are either from the sand/aggregate or from red dye added to the plastic mix.

 

[darthsoilsguy2]

if you're afraid the mortar froze, take your keys across the joint next time you're there and you'll know it.

I've seen this block issue before on plenty of walls built in the summer fall and spring.... but i haven't thought about it much. too busy thinking about all the other f-ups going on and how i'm going to monkey up that scaffolding.

 

[concretemasonry]

The photo really shows very little of importance.

First, block block are fully cured before any delivery to the project is possible. Block are made using a zero slump concrete that is cured prior to shipment. The storage of the materials is dependant on the specifications.

Second, the construction of the wall apparently should have been done according to the "cold weather construction requirements", available from the NCMA or IMI or the requirements in ACI 530. This is to prevent any problems with the mortar since the block are already cured and amnufactured to the very, very minimal specifications in ASTM C90.

Third, the grouting of the wall must be done acccording to the requirements in the ACI 530, TMS documents and recommendations by the MCAA for cold weather construction. The important factor is the absorption of the excess moisture required in the ASTM grout specifications.

Color is a very arbitrary measurement of the condition of a wall. Walls are normally designed to be able to withstand the weather conditions for the local climate.

Since this is a wall that is grouted after the initial construction, the details and specificatins may yield some information before try to determine the real condition of the wall after grouting and the surface distractions are resolved.

This may be a typiccal case of over-design and making the wall depend on materials that are hidden and really not required that make reliance on the unseen and unnessesary, a complication on the real structural requirements - according to James Amrheine (sp?), a leader in masonry design, codes and construction.

there are really few recognized testing proceedures for the suitability of walls under construction.

Dick

 

[Einsteim]

It appears that whatever the reddish color on the scaffodl planks made its way on the face of the CMU wall. Spilled chalk from a chalk box, residue from rosing paper on a previous job? .. thinking out loud obviously..

 

[boffintech]

Both the IBC and ACI530 require continuous inspection during grout placements and periodic inspection during block placement. The inspector should have recorded the project site conditions and protection of the work in-progress. What, if anything, do the reports by the certified special inspector state?

 

[dik]

I came across one wall that hadn't been horded and heated and checked the mortar with my pocketknife only to find the mortar still plastic. I told the contractor super that the wall should be enclosed and heated and was informed that the wall had been constructed yesterday... Temperatures were about -20 and had warmed to near zero.

Dik