MSE Wall Cosmetic Remedy

[jdonville]

We are completing construction of a new MSE wall that uses panels with a pigment mixed into the concrete. One of the panels arrived on site with a noticeably different appearance (apparently due to residue in the forms from a previous job performed by the precaster).

The panel in question was installed several rows below the coping, and one of the owner agencies has waited until the end of the construction to raise objections over the appearance of this one panel.

We would like to modify the appearance of the panel in-place, and are open to suggestions. We have not yet applied an anti-grafitti coating. Any information on possible surface treatments, including information on long-term maintenance impacts, would be appreciated.

Jeff

 

[jdmm]

You might want to go to a forum on concrete but if you think that you would like to replace the panel, it is probably do-able. I have had many cases of arching around vertical panels that have been removed and have excavated behind MSE walls to depths of 10 feet at the back of the reinforcement. In contrast to most of the recommended procedures for design of walls (ie FHWA) there is no pressure at the back of the wall and the excavation stands vertically. You might consider removing the panel and replacing it and possibly grouting behind. From what you say, it sounds like the 'authorities' have waited to the end as a pressure tactic for the contractor

 

[Panars]

If you were to replace the panel, how do you attach it to the soil reinforcement or otherwise seure it? I have a developing situation where the panel is disintegrating and will need to be replaced.

 

[TDAA]

Talk to the precaster. They might have a solution. What about rubbing the surface with some of the appropriate color mix to see if you can blend it to a closer color? Also, I am not real familiar with the anti-graphitti coatings, but could they be tinted as well?

 

[civilperson]

Dyes for concrete over the panel in question and all other panels in this view will bring uniformity. Try a sample to see if owner's artsy eye will approve, (I hate people who can see colors!)

 

[MSEMan]

I was involved in several projects that used pigmented panels in the past. I'am assuming that the surface is smooth? If so the panel can be bag rubbed using the pigmented mix. However, be aware that you might end up bag rubbing the whole wall to get a uniform appearance.

 

[concretemasonry]

Based on 30+ years of production and use of pigmented concrete products, I would ask the obvious questions before attempting to correct the appearance:

1. What is the real reason for the concrete color variation? Is it just dirty forms and producer negligence or is the concrete actually a different color due to bad batching/mixing? Surface form contamination will wear off unless the producers was extremely negligent.

2. Is the color different due to site conditions - panel storage methods, exposure, etc?

If you attempt to "bag rub" the wall, make sure you use the same pigment type and allow the rubbed area to age before committing to rubbing the remainder. Any "colored" concrete will be tinted with a pigment (usually a synthetic iron oxide) because of the permanent nature. As the concrete cures, the apparent color will lighten because of the natural cement chemistry process. That is the reason all cement-based color samples (concrete, concrete block, mortar, grout, etc) are well cured before being made available to the specifier.

Avoid anything (stains, coatings, etc.) that refers to dyes, since they are not as permanent as the pigments in the concrete.

When providing samples to the owner, always submit 3 samples exposed to the natural lighting conditions and do not make the decision inside where there is atrifical lighting. The surfaces must also be the same finish and texture since this has an effect of the apparent darkness/strength.

Dick

 

[jdonville]

All,

Additional info:

I am informed that some chemical treatment was attempted on the surface (below the final ground line) with not-so-great results.

The precaster decided to sandblast the panel. The sandblasting definitely improved the overall appearance. However, the panel was deemed unsatisfactory by the agency, which brings me to my original post.

I will discuss the rub option with our project manager and precaster.

Jeff

 

[MSEMan]

Definately look at a bag rub, when I was a very young lad, I had to do this on a high profile project for RECO. As a much older person I had to pay for my staff to do it. It works. The process is labour intensive but it does work, and the effect is permanent.

 

[jdonville]

As of this time, we are planting a shrub in front of it.

Jeff