Thread: Laitance on a new slab - how to approach removal/repair?

Originally Posted by Collins

After curing and building house, suffered from excess dusting. Swept and vacuumed area thoroughly then sealed with paving paint. Carpet layers, when carpet eventually laid were rapt - no dust.
There was no need to blast or acid wash as the surface was already roughened to allow proper bonding/penetration of the sealer.

That's what I did with my current shed which had part of the floor affected by dusting. Unfortunately, as soon as a car drives over it & turns the steering, the paint comes off.

I agree with not putting on paving paint. You'll have to strip the loose material which will expose the aggregate which will leave a uneven high maintenance floor

I still wouldn't eliminate a thin (5-10mm) polymer screed as a solution, do not confuse this with an applied coating/sealant.

In my experience with specifying ground slabs its so slow.

If the laitenance is weak as it should be then it will come of with a high pressure washer, which will expose the aggregate ready for a screed topping like the parchem topping (ther are others) I posted up before. You could just use a sand/cement screed but this wont perform as well.

This will give you a 100mm thick slab, it will be smooth and dust free and it will not need re-coating every year. There will be a cost someone will have to pay but this in my experience the best long term solution.

I work in construction and do a fair bit of concreting and dealing with concrete,I would be speaking to the company that poured it as on a raining day like that there is no way I would have let anyone pour in those conditions,it is a totally unsatisfactory finish and u want it redone

Just to be clear, Im not saying to hang the concreter out to dry. I am totally aware of his situation and that of all the various pressures in construction, especially on site on the day.

But, as he is the one responsable for placing and finishing the concrete, and that is his TRADE, it is his call. I have had flat out arguemnts with concreters, pump operators etc over weather, watering down mixes, cover, vibration etc. When you look at the big picture (structural integrity, finish quality, defects call backs) sometimes you have to stand your ground. If it means they pack up their bat and ball and go home, so be it.

It sounds to me that he knows there is a problem. If he is worth his salt, he will come to the party. It may not be 100% but hopefuly you can both agree on what is fair.

Originally Posted by clive22

Whoever is responsible under the contract.

Clive

Parchem products are not cheap, can be and are technical in application, need a decent skill set to apply and are not a silver bullet. They can also result in re-work of re-work because people think they know best with regards to application. I have spent hundereds of thousands at Parchem (not an exaggeration either, HB70, HB40 FC you name it)

I'm thinking Scouse will not be ticking a few of those boxes and considering the concreter's current efforts I would be reluctant to enlist his services whether at his cost or not.

My vote is not for the Parchem solution.

Regards
Andrew

So what is your solution? The OP asked for one and you have not got one.

You say that Parchem may not work and has to be reworked due to lack of competency during application.

Duh! This applies to anything anyone does at anytime and is an inane comment.

I'll stick with what I said a screed solution such as Parchem there are plenty of others if Parchem is not your flavor of choice and with what I know about the job the best technical solution.

Naturally any solution will have to be applied in a competent manner.

Sorry to hear Scouse!!!

If it really needs to be ground back 5 or 10 mm I would be getting them to grind it (and pay) and then refund you (at minimum) for the ~2.5 m3 of concrete you don't have any more... (that's assuming a 90 mm slab would be strong enough for your use).

I poured a slab in the rain recently but it was small enough to set up a tarp over it.

Originally Posted by isuzurover

Sorry to hear Scouse!!!

If it really needs to be ground back 5 or 10 mm I would be getting them to grind it (and pay) and then refund you (at minimum) for the ~2.5 m3 of concrete you don't have any more... (that's assuming a 90 mm slab would be strong enough for your use).

I poured a slab in the rain recently but it was small enough to set up a tarp over it.

one would hope the fabric being set up well enough that grinding alone will not reduce the cover below the required amount.