How come some concrete is pitted from winter salt and some isn't?

[crazyal]

I still have lots to learn. The cement will be poured on a slope so I need to learn how dry it needs to be.

 

[vtsnowedin]

I still have lots to learn. The cement will be poured on a slope so I need to learn how dry it needs to be.

Order it delivered with a 2" slump. Plastic but plenty stiff that way and it will stay where you put it. You still have to start on the low side and place and finish up hill. Of course a driver that doesn't like you might not give you a two.

 

[cdaigle430]

I don't understand why my neighbor's garage pad is all pitted and flaking from winter salt corrosion yet the concrete pads at the gas station look as good as the day they were poured. Is it merely the PSI strength of the mix or some dark masonary secret?

Even better question is how to fix it and keep it from happening again?

 

[vtsnowedin]

Even better question is how to fix it and keep it from happening again?

There are no cheap fixes. Bust it out with a demo hammer on a skid steer. use the rubble for fill someplace muddy and redo it right with a high strength mix and a crew that knows what they are doing. Some siloxane water proofing/sealer before you put any salt on it wouldn't hurt as well.

 

[don45640]

CrazyAL .......the guy who told you order a 2"slump means well,but, he doesn't know what slope you have.I don't either,but you can pour DOWNHILL with a 4"slump very easily,unless it's more than 5"thick.
Thickness of the pour has EVERYTHING to do with pouring on a slope.
Also,crushed stone will hold better on a hill than river gravel that is rounder.
In short,every pour is different,requiring a different strategy if skilled labor isn't at hand.A skilled concrete finisher RARELY pours uphill......it's way too much WORK!
Also,to the guy who claims flyash is a better way to go....BALONEY! Flyash has been used AGAINST homeowners to STRETCH the mix(they may even cut the cement used when they add flyash)......nothing is a substitute for the proper amount of cement.
Also,the finisher IS at fault a lot, but not any more frequently than the `CEMENT Stretchers'batching it out. don-ohio ^)

I still have lots to learn. The cement will be poured on a slope so I need to learn how dry it needs to be.

 

[Egon]

Even better question is how to fix it and keep it from happening again?

Remove and replace with a new pour.

 

[vtsnowedin]

CrazyAL .......the guy who told you order a 2"slump means well,but, he doesn't know what slope you have.I don't either,but you can pour DOWNHILL with a 4"slump very easily,unless it's more than 5"thick.
Thickness of the pour has EVERYTHING to do with pouring on a slope.
Also,crushed stone will hold better on a hill than river gravel that is rounder.
In short,every pour is different,requiring a different strategy if skilled labor isn't at hand.A skilled concrete finisher RARELY pours uphill......it's way too much WORK!
Also,to the guy who claims flyash is a better way to go....BALONEY! Flyash has been used AGAINST homeowners to STRETCH the mix(they may even cut the cement used when they add flyash)......nothing is a substitute for the proper amount of cement.
Also,the finisher IS at fault a lot, but not any more frequently than the `CEMENT Stretchers'batching it out. don-ohio ^)

I don't know much about it. I only made 115 ACI certified test cylinders last year that averaged over 6000 psi. Every one of those had either fly ash or ground mill slag in the mix. You can use what ever you want.

 

[Egon]

Fly ash fills voids the granular mix is missing.

 

[adirondackmtnman]

CrazyAL .......the guy who told you order a 2"slump means well,but, he doesn't know what slope you have.I don't either,but you can pour DOWNHILL with a 4"slump very easily,unless it's more than 5"thick.
Thickness of the pour has EVERYTHING to do with pouring on a slope.
Also,crushed stone will hold better on a hill than river gravel that is rounder.
In short,every pour is different,requiring a different strategy if skilled labor isn't at hand.A skilled concrete finisher RARELY pours uphill......it's way too much WORK!
Also,to the guy who claims flyash is a better way to go....BALONEY! Flyash has been used AGAINST homeowners to STRETCH the mix(they may even cut the cement used when they add flyash)......nothing is a substitute for the proper amount of cement.
Also,the finisher IS at fault a lot, but not any more frequently than the `CEMENT Stretchers'batching it out. don-ohio ^)

Actually the world trade center tower recently completed in NYC acheived 17000 PSI breaks in 56 days cure time with just over 300 pounds portland cement...the rest of the over 900 pounds of cementitious per yard was flyash, slag and other pozzolans. Crying 'baloney' doesn't hold water with emperical data...I'm an ACI certified concrete technician, and design concrete for a living and I can show you plenty of properly mixed concretes with flyash that far outperform straight cement mixes in most scenarios. Flyash can reduce the initial heat of hydration, yeilding MUCH better long term curing. The flyash also reacts with the byproducts of the hydration of the cement, and creates a secondary cementitious reaction. There's a reason why flyash is demanded by municipalities and private projects alike...It works...If you don't know the science behind the mix, you cannot simply assume the producer is 'stretching the mix' and blame a poor laydown and finish on the producer.

 

[adirondackmtnman]

I don't know much about it. I only made 115 ACI certified test cylinders last year that averaged over 6000 psi. Every one of those had either fly ash or ground mill slag in the mix. You can use what ever you want.

We make upwards of 200 sets of cylinders(Also ACI certified) in our lab in a years time, both field and lab created specimens, and I too can say that the flyash/slag/microsilica mixes far outperform those without, with a lot of economical benefits to the customer:thumbsup: