Rain While Pouring Concrete Driveway/Wrong Concrete Delivered 3

[walker57]

We had a driveway and walkway poured recently and it started to pour rain. Puddles were forming on the half of the driveway that didn't have anything on it yet but they kept pouring and the concrete was looking quite sloppy. The rain got a bit lighter, but still kept falling on the concrete while they were trying to smooth it with the boards. We are concerned that the driveway is going to have problems because for several minutes during the pour, the rain got very heavy. I included a picture where you can see the drops. The walkway was being poured while there was a heavy downpour. How worried should I be with all the rain being mixed in with the concrete?
Not only that, but our order/contract specified that fiber mesh be mixed in with the concrete, but we found out the next day that they forgot to add it in! We did have wire mesh laid on the driveway...and it was also supposed to be on the walkway, but they forgot to put the wire mesh down there!
Any suggestions on whether we should pay this company? The sales guy is also the son of the owner and he was supposed to oversee the project but was out of town. He knew there was a good chance of isolated showers but ordered the guys to pour it. He didn't even realize the fiber mesh wasn't in the concrete until we examined it and texted him and he admitted it was not there.
When they pulled the boards off the walkway the following day, the edges were jagged and chipped and pieces broke off on the sides...which they just patched up.
Clean up was terrible with muddy cement from the run-off powerwashed down into the street in front of our driveway and also down the neighbors front curb and left there. And...muddy cement splattered from the powerwasher all over 2 of our newly leased vehicles in the street. The cement splatter was baked on by the sun all afternoon before we saw it so we now have to get it specially cleaned and detailed so we don't scratch the finish.
It has not been a very good experience.
Considering the driveway was poured when there was heavy rain, forgetting to have the fiber mesh included in the concrete and also forgetting to put the wire mesh in the walkway, completely splattering our vehicles with muddy cement (which baked on from the hot sun)....any suggestion on what would be a fair way to handle this?

We do not want them back at the house to do any more work because there is now a trust issue and we don't want any more bad experiences.
By the way...yes, I did research them and they have been in business for quite a while and this is also a company that has good reviews on Angies List and no complaints yet on BBB.

 

[TehMightyEngineer]

Fair way? They demolish and repour or they pay you so you can get it demolished and get another company in. I would not pay them, the extra water from the rain on the surface of the concrete has almost certainly ruined its durability. If they've been in business that long they will understand they screwed up and need to make it right.

Professional Engineer (ME, NH, MA) Structural Engineer (IL)
American Concrete Industries

https://www.facebook.com/AmericanConcrete/

 

[dik]

I would have them remove it and re-pour it at their expense providing proper materials and correct construction. I would avoid WWM and use rebar properly chaired. Important that it be sawcut at the correct time. Without a sofcut type of say 6 to 8 hours after finishing... with a sofcut, a couple of hours.

What is your climate like? Do you use de-icing salts?

Dik

 

[walker57]

They had 10 gauge wire mesh in the contract (and we also wanted the fiber mesh along with that mixed into the concrete). Is the rebar more expensive, better and more time consuming than wire mesh? Just wondering if we tell them to alter the contract for that if it will make a difference.
Saw cutting was done next morning. Are you saying soffcut is better than saw cut? We are in Michigan so nice summers, but snowy and ice in the winter. We have used de-icing but will try not to with the new concrete.

 

[dik]

I have a personal problem with using WWM... rebar is definitely better. It may be a little more expensive due to placing. Take a gander at the slab when they cut it out and see if the WWM hasn't been trampled to the bottom of the slab. Rebar (and WWM) should be approx 2" from the top of the slab if done properly.

Sofcut is better than regular saw because the sawcutting is earlier. You want to cut the slab before shrinkage has 'taken over'; this happens early in the history of the slab. Sawcutting the next morning is likely a tad too late... maybe a midnight. The concrete should just be hard enough to prevent aggregate from 'ravelling' (kicking up) behind the sawblade.

You should also be looking at entrained air about 5% to 7%, and concrete strength should be 30 MPa, minimum. Slump should be 4" maximum. Proper curing of the concrete should happen.

Dik

 

[walker57]

Will the rebar cause any rust marks?

 

[SlideRuleEra]

Will the rebar cause any rust marks?

Agree with Dik about WWF being of little value and rebar being best. To answer your question, to minimize rebar rusting the rebar needs to be 2" from the top (per Dik's comment). However, at the same time the rebar needs to be 3" above the bottom. The rebar, say #4, is 1/2" diameter and is installed in a mat (spaced bars running in two directions). Therefore the mat needs 1" of thickness. Total slab thickness, 3" + 1" + 2" = 6".

Many residential slabs are 4" thick.

A compromise suggestion:

1. Make the slab 6" thick (If nominal 6" lumber is used for forming the edges, 5 1/2" thick is ok).

2. Make sure the Contractor has compacted the soil under the slab before any concrete is placed.

3. Don't use WWF or rebar. Do use fiber mesh.

4. Put joints in both directions no more than 10' apart.

5. Don't use any kind of "cure and seal" compound. Do have the Contractor completely cover the slab with polyethylene sheets as soon as the concrete has cured enough to walk on without making any marks.

6. Tell the Contractor to go away and come back in one week.

7. Two or three times a day you place a garden hose under the polyethylene and keep all of the concrete as (continuously) wet as possible.

8. One week later the Contractor removes forms and the polyethylene then goes away for good.

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[walker57]

Thank you.

 

[Ron]

SRE...perfect!

 

[dik]

SRE: I disagree with your item 3; I would not use Polypropylene Fibres. Other than affecting the bleedwater they have little effect.

I thought I had posted this earlier, but, gremlins...

Dik

 

[hokie66]

There are as many opinions about how to build a driveway slab as "Carter has Little Pills".

 

[SlideRuleEra]

Thank you, Ron.

Dik - The OP wants fibers, I like them, but agree they are really optional.

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[hokie66]

SRE,
Why do you like fibers? I assume you mean the plastic ones, which I consider to be useless.

 

[SlideRuleEra]

hokie - Yes, plastic fibers. In a word, "Toughness".

In the mid-80's we were completing a new generating station. Our Consultants had been specifying WWF for the few unreinforced slabs used. Typically a limited number of small, 6" thick ones in "housekeeping" areas... say, just outside the doors of outlying pre-engineered building. I knew WWF has limited value; plastic fibers were being introduced as a replacement for WWF.

So, for a couple of our in-house projects at the plants used plastic fiber instead of WWF. Can't say that plastic fiber was better than WWF, but it was not any worse. Read the literature about plastic fiber possibly improving concrete toughness - that caught my eye. All our concrete has a "hard" life - impact from heavy items, large equipment bumping into it, etc. So, for the next plant we changed the "Criteria Document" that guides Consultants to our design preferences. Plastic fiber instead of WWF for minor 6" slabs.

Never tried steel fibers, with potential for corrosion from coal and process chemicals, didn't seem like a good idea.

http://www.SlideRuleEra.net

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[hokie66]

If you really need toughness, e.g. in heavy equipment maintenance shops, steel fibre concrete will do it for you. The corrosion at the surface creates a bit of staining, but is not an issue in that environment. I have used steel fibre concrete in workshops that maintain dozers, dragline buckets, etc.

But we digress. The OP's problem is a residential driveway. Where I am, most driveways are exposed aggregate or some type of stamped or applied finish. Very few plain concrete. If exposed aggregate, I think the fibres would create a fuzzy sppearance when the pressure washer does its job.

For reinforcement, we do tend to use heavier welded mesh reinforcement than I think you are referring to.

 

[hokie66]

This is the type finish which is prevalent for driveways here. I think plastic fibres would make it fuzzy.

http://www.hanson.com.au/Portals/1/...ete/Decorative/ImagecreteexposeSEQLD Card.pdf

 

[Ron]

hokie66...you are correct about the fuzziness. It does occur with poly fibers. We recommend hitting the surface with a roofing torch or similar. Melts them away...issue gone.

I'm not a fan of welded wire fabric except in flat sheets (not the rolled stuff). For lightly loaded slabs on grade, I think any reinforcement causes more issues than it solves. There is no substitute for a proper mix design, properly placed, thickness controlled and proper/timely sawcutting.

As for fiber....I'm a fan of steel fiber for mix enhancement, not reinforcement. It significantly increases the toughness. I was on ACI Committee 544 on fiber for much of the 80's when there was great fighting and gnashing of teeth between the synthetic fiber producers and the steel fiber producers. A lot of testing was done and some good info came from that; however, the long running discussion between the importance of first crack mitigation and long term cracking (poly for first crack mitigation)will never be resolved and, in my ever-so-humble opinion is a waste of time. Pick the fiber you want (or none), design the mix for it, place and finish it properly, then sawcut it as if there was no fiber in it.

Getting back to the OP.....that was miserable placement of the concrete. Have them remove it and have a competent crew prepare the substrate and place the new concrete properly as noted herein.

 

[dik]

Ron:

Agreed, an excellent reply, except I would still provide reinforcing even for lightly loaded slabs. Sawcutting is the real 'kicker'... has to be done and at the correct time (I cannot stress sawcutting at the correct time, enough).

Dik