Concrete Restoration

[phil327]

This is probably more of a ' Is this the right way to do this work '
Three items
The company is behind schedule and they are starting to hurry things up.

1. They did repair work on the concrete and smoothed it over with a layer of stucco. They then painted the stucco a 4 days later. Most information I have seen suggests 2 weeks minimum for the stucco to cure. Is this painted to soon?

2. They are sandblasting some of the rebar and old concrete. There is no containment and the sand blast material is blowing all over. They are also painting some of the exterior of the building at the same time. ( I do woodworking and one thing you don't do is create dust and paint at the same time )

3. Cleaning up they are using a leaf blower to clean up the debris. This afternoon they had to remove a wooden frame, with fiberglass insulation from one of the balconies. This framework must have had a significant water leak, because the wood was rotted and covered with black mold. There were also termites present. They chipped away some of the concrete on the balconies above and below. They are working on scaffolding and there are workers on 3 other scaffolds down wind from this particular unit. So - they start up the leaf blower creating a dust storm of concrete dust, black mold and fiberglass insulation. This went on for over 30 minutes as they went down each balcony to remove the debris. The workers downwind were treated to all this airborn debris, as well as any one who happened to be out side at the time. I would have thought that an industrial vacuum would be the way to clean this up, slower that a leaf blower, but much better.

Are these just "ROOKIE" mistakes - this is a fairly new company.

[phil327]

I am starting to feel like the 'Negative' person here. Or maybe one of a few who has some background and sees what is going on. The latest adventure concerns pouring in the concrete into those areas on the walkways that did have some damage. I'll make up some numbers because I am not going to count all the small separate areas, They put wood forms around the repaired areas leaving the top open. let's say there were 100 spots to pour concrete into and only 2 workers - this is not an accurate number. So, they started on the upper floors and did a fairly good job getting everything level and smooth. As the day progressed and they worked their way down, the repaired areas got much less level and not smooth at all. Someone commented that it looks like they put the concrete in with an ax. We are being told now that those areas will have to be ground down and 'polished' to make them level with the existing concrete.

It seems to me that the concrete has started to set up and cure as the day went on. Looking at it now, it appears they had too few workers and too many areas to fix. Simply put, they either should have gotten a separate concrete delivery in the afternoon, had more workers available, or not tried to fill as much as they did. I wonder about the stability and strength of the concrete that was put in place later in the day - I'll bet there are air pockets and the concrete will not bind all that well to the existing concrete.

Any comments would be appreciated.

[Jerry Peck - Codeman]

[phil327]

We surveyed the repairs earlier today. About half the repairs have cracks where the new concrete meets the old. These are about 1/16 inch all the way around the repaired area. It also looks like the concrete is depressed towards the center of the repair. If I had to guess, there was water added to the mix, then the water evaporated effectively shrinking the new concrete. Some of the repaired areas are extremely rough.

thanks for your earlier answers

[Jerry Peck - Codeman]

The cracks all the way around basically indicate that the new concrete underwent shrinkage, quite often from too much water, as you suspect.

While the steel is what provides the strength (versus the strength of the bond) the strength of the bond and tightness of the bond is what helps keep moisture out of the joint between the existing concrete and the new patch concrete.

Your description indicates that water may have been added to the mix, and (for most mixes) the tickets will state either 'no water to be added' or 'X amount of water may be added by driver' and then that 'x amount' of water should not be exceeded. If no water is authorized on the batching and delivery ticket then no water should have been added - by anyone, not the driver and not the concrete workers. I recommend getting a copy of the batching and delivery ticket and see what it says about the mix, the maximum time between batching and use, and the addition of water.

[phil327]

Just a quick picture or two to show what I am talking about



this one is the walkway edge, where they will attach the new railings. The swirl marks are from the grinder they used to level the repair. I have more pictures, but this is representative of the most of the work.

[Jerry Peck - Codeman]

You say that they used forms?

Looks like they applied it by the handful and then tried to pat it out with a trowel - like it was already setting up as you said.

[phil327]

I got into a discussion earlier today. I had seen a lot of concrete poured into foundation forms in NY. Basically the basement of a house below ground. The forms were 4x8 panels spaced 6-8 inches apart and set on previously poured footings. The transit mix truck poured the concrete into the forms. The workers would 'jitter' ( not sure if that is the right word) poured concrete to make sure the concrete gets into all the areas and there are no air bubbles ( Jitter - vibrate the concrete, or tamp it while it is still fluid ) The top is leveled by scraping a board across the top of the form, then smoothing it with a wide trowel. A few days later the forms are removed.

At this point in time the concrete is smooth on the top and sides, no additional work is needed.

The work here, including the work poured into forms, gets a layer of stucco, then a grinding to make it smooth. It seems to me that if the work is set in the forms correctly, no additional work would be needed.

[Jerry Peck - Codeman]

"It seem to me that if the work is set in the forms correctly, no additional work would be needed."

Typically, only limited work is needed to remove concrete irregularities due to the forms and/or tightness of the form joints.

Concrete work is considered 'rough work', not 'finish work', and therefore has liberal tolerances. Nonetheless, though, what I see in the photos exceeds even those tolerances (from my perspective of just looking at the photos).

[phil327]

This is not completely on topic but does fit in with concrete forms. There were a few commercial buildings in NY that used very rough saw lumber for the sides of the forms. When the forms were removed, the concrete had the look of rough cut lumber, even down to the grain pattern of the wood. Visually appealing, but don't brush up against it, like sand paper.

[phil327]

And today they were grinding the balcony edges, and to keep the dust away from the worker - a 3 foot industrial floor fan aimed at the person doing the grinding, blowing all that dust and dirt into the pool area......

[Jerry Peck - Codeman]

Sounds like someone lacks common sense, does not care, does not think, does not know what they are doing, or maybe a combination of the preceding ... now they need to clean the pool, filter, deck, chairs and everything else they got that dust on - maybe they just have so much money that they don't care how they spend it?

[phil327]

Just to keep this interesting. They finished grinding the stucco that was applied over the concrete that was poured into forms. These are open balconies, a ceiling, floor, and three walls, with one area open for windows or screens. Hook up the power washer and power wash, with water, the walls, floors, and ceilings. This would be fine if the entire enclosure was just concrete, but, they are not. Some have ceiling fans, still in place. I doubt if the the blades are suitable for out door use, plus the motors are not water proof. Additionally, there are a few units that appear to have painted wood paneling.

I am not 100% certain, but, some water got into the fans, some water got behind the wood paneling.

Just unbelievable....

[Jerry Peck - Codeman]

[phil327]

I should have mentioned that these were originally enclosed balconies, they had jalousie windows installed, I do know that some of the units had permits for the jalousie windows.

I have seen ceiling fans for damp locations, my understanding is that the main difference is that the blades are not made of wood.

[Jerry Peck - Codeman]

[phil327]

I took a walk on the walkways today to see what was happening. The construction company has put a thin layer of "stucco" on all the cracks and areas that shrunk. I am not sure what compound they used, but is is rough and very thin. These are areas that will be walked on, have hand trucks and all kinds of other traffic rolled and pushed across.

Is spreading a thin layer an accepted method to repair the walk ways? Oh - pretty sure they will grind these down to make them level with the old concrete.

[Jerry Peck - Codeman]