New Concrete driveway has Zits

[mscheer772]

In July of 07 I had my asphalt driveway replaced with concrete. The concrete is now flaking and popping all over the driveway.It is especially bad at the control joints. Does anyone know what is causing this? I did not use any salt to melt the snow off the driveway.

I'm told that it could be bad concrete, bad pour,bad finishing, bad curing. Someone said that the salt from the cars could do this.I don't know what caused this problem, but I'm pissed that my brand new driveway looks like sheeot.

Is the contractor at fault?

How would you go about fixing the problem?

Thanks in advanced for any and all help

-Mike Scheer-

 

[Soundguy]

I don't know how thick a pour you had.. etc.. and I havn't seen any pics.. but I'm going to venture a guess that the top dried out and was not kept wet, and it was a thick pour, so the top deforemed a bit..

post some pics..

soundguy

 

[Egon]

Some one added to much water to the mix to make it easier to work!

Standard ???/ sub contractor contractor activity.

 

[CDsdad]

I don't know how thick a pour you had.. etc.. and I havn't seen any pics.. but I'm going to venture a guess that the top dried out and was not kept wet, and it was a thick pour, so the top deforemed a bit..

post some pics..

soundguy

What he said. That or the exact opposite. It didn't rain hard on it right after the pour, did it? That happened to my parents several years back. The dryed out deal happened to an uncle. Both flaky, uncle's was worse.

A thin, soupy pour won't necessarily make it flake, though I guess anything is possible. It'll have a funky, melted look on surface.

 

[orezok]

It is most likely contractor related. Without pictures it is difficult to say, but one cause of this type of spalling is that the contractor gets in a rush and tries to final finish it before the water has a chance to evaporate. This pushes the excess water back into the concrete thereby causing a very high water cement ratio at the surface and weakening the mix.

 

[Botabill]

A picture would help. Perhaps the finisher worked the surface too much and too smooth. Looks good at first then flakes off. A broomed finish is best for outside surfaces from my limited experience.

 

[TwinWillows]

I agree a picture would help but I'd offer that other than expansive aggregates in the mix (rather uncommon but possible) spalling is most frequently caused by any or all of the following; improper finishing, too much water in the placed concrete or improper curing/weather protection after the pour.

 

[rimshot]

Steel trowel used too much and too early, dirty aggregate with too soft stones that absorb water and then pop when weather freezes, rain, snow or was it poured in sub freezing weather which causes surface to freeze..

rimshot

 

[nckubota]

Sometimes the finisher gets ahead of the concrete curing, I have seen finishers take dry cement (powder) and scatter it across the surface of the wet concrete to absorb the water standing on the surface. This thin layer of infereior cured concrete will almost always spall/crack/flake off the surface of the slab.

 

[trrjohn]

Some aggregate used in the concrete absorbs water ( called chert ). The aggregate sucks up water and the freeze / thaw cycle pops out small areas - known as spalling -in the vicinity of the "chert". Some concrete suppliers advertise "chert free aggregate". Weaker types of limestone are also prone to spalling.

Too much water in the mix typically causes dusting or scaling, but not little cones from poping out.

A stronger concrete mix design helps. (6 to 6-1/2 bag mix) Adding Fly Ash in place of a portion of the cement really reduces the permieability of the concrete ( amount of water able to be absorbed (sucked) into the concrete ) and helps significantly with chert pops. John