After one week: Concrete still green AND pliable!

[FTG-05]

Poured a weight block last week, Thursday August 17 in the AM, to be exact.

I kept the form and concrete both wet and covered with plastic until yesterday afternoon, when I moved it into my shop so I could get it out of the way.

Took off one end of the form this morning (i.e. exactly one week after the pour) and the concrete was not only still green looking (instead of grey) but also still pliable! Parts of it hadn't hardened at all! I stopped taking off the form at this point.

Pics:

In the 2nd pic, you can clearly see my thumb indentation in the center. I'm pretty sure concrete is supposed to be stronger than that.

Recipe is as follows:

80 lb bags of standard Quikrete concrete mix, about 3-4 quarts of water per bag and 8 oz of BASF 1025 superplastizier. Quikrete recommends 3.5 quarts of water with a maximum of 4.5 quarts. I don't believe I exceeded this amount and probably it was a bit less. One of the purposes of this pour (besides getting a weight box and using the concrete before it went bad) was to test the SP).

I mixed the dry ingredients for about one minute, add water for about 2 minutes, let that mix for 1-2 minutes, then take a minute to add the SP. After all ingredients are added, I mixed it for an additional 3-5 minutes. ETA: Mixing was all done via a HF electric 3 cu ft mixer.

The top itself seems hard and has turned grey, although it's not shown in the pics.

What happened here and is this salvageable?


Now can you see the pics?

 

[06 DIESEL]

I can not see pictures, but it might be the filter on my computer.

Superplastizier is a retardant for concrete, it will take weeks for a thick chunk of concrete to harden if you use it.

 

[850xpeps]

I can not see pictures, but it might be the filter on my computer.

Superplastizier is a retardant for concrete, it will take weeks for a thick chunk of concrete to harden if you use it.

Wrong super p will retard the setup initially but will setup quick after.
If it's been decently warm then you have some issues with your cement.

 

[rburke65]

No....no pictures here either.

 

[Richard Cranium]

no pictures either.

 

[GMCGarage]

If just a weight block, leave in the form, still weighs the same basically.

 

[G-ManBart]

Superplastizier is a retardant for concrete, it will take weeks for a thick chunk of concrete to harden if you use it.

That's not entirely true. Yes, super P is a retardant, but it shouldn't take weeks for it to harden. I drove a redi-mix truck during the summers during college, and poured a lot concrete with super P in it. With the right amount, you should be able to walk on it the next day.

 

[MoonRise]

(pics don't immediately show up because they are imgur ones. do the 'strip off the leading "i." from the link and then they will show up.)

You were at the higher end of the SP dosage, but not excessive. Dosage info from the spec sheet says 3-12 oz/cwt.

https://assets.master-builders-solu...sterPolyheed/basf-masterpolyheed-1025-tds.pdf

And set-up time with the 1025 SP is listed as about 25 minutes longer than just plain concrete (5:05 with 1025SP versus 4:40 for plain concrete).

Something really doesn't seem right with your results.

Unless you are The Hulk or some other superhero, you shouldn't be able to make a thumbprint in 7 day old poured concrete.

 

[58Yeoman]

Don't the forms normally come off the next day or so?

 

[bcradio]

Don't the forms normally come off the next day or so?

They can, but they can also stay on permanently if you like. Minimum would be a day or so though.

 

[850xpeps]

If it's a wall or something large then forms should stay on in cases up to 7 days for proper strength. But the concrete shouldn't be soft

 

[kTHREE]

 

[850xpeps]

Any powder in it? Lol looks like pure sand

 

[FTG-05]

(pics don't immediately show up because they are imgur ones. do the 'strip off the leading "i." from the link and then they will show up.)

You were at the higher end of the SP dosage, but not excessive. Dosage info from the spec sheet says 3-12 oz/cwt.

https://assets.master-builders-solu...sterPolyheed/basf-masterpolyheed-1025-tds.pdf

And set-up time with the 1025 SP is listed as about 25 minutes longer than just plain concrete (5:05 with 1025SP versus 4:40 for plain concrete).

Something really doesn't seem right with your results.

Unless you are The Hulk or some other superhero, you shouldn't be able to make a thumbprint in 7 day old poured concrete.

You're right about the dosage. I was working off of 1 oz/10 lbs of mix, but I don't recall where I got that. Obviously not off the 1025 data sheet.

I'm +62 years old, definitely not the Hulk.

 

[FTG-05]

Any powder in it? Lol looks like pure sand

Nope, nothing but what I wrote for the recipe: Concrete mix, water and SP, thoroughly mixed, kept wet/damp for a week.

I could understand 1, maybe 2 bags of concrete mix not to spec, but 5 1/2 bags? They were less than 2 weeks old from HD.

 

[Leaflessshadetree]

Just a big hunk of concrete, its going to take longer than a 3-6" slab. Also the forms held the moisture in. Google concrete curing time on large dams, you will probably be surprised.

 

[FTG-05]

Just a big hunk of concrete, its going to take longer than a 3-6" slab. Also the forms held the moisture in. Google concrete curing time on large dams, you will probably be surprised.

Good point: Dimensions are 60"x12"x8", about 5 1/2 80 bags of concrete, approximately 440 lbs without the rebar frame.

Pics of the concrete mix before and after the SP:

Concrete Before SP:

Concrete After 4 oz of SP and mixing for one minute - NO additional water added!

Pic of the form, rebar frame and first 80 lb bag. Note how the concrete has almost self-leveled itself inside the form.

 

[FTG-05]

(pics don't immediately show up because they are imgur ones. do the 'strip off the leading "i." from the link and then they will show up.)

You were at the higher end of the SP dosage, but not excessive. Dosage info from the spec sheet says 3-12 oz/cwt.

https://assets.master-builders-solu...sterPolyheed/basf-masterpolyheed-1025-tds.pdf

And set-up time with the 1025 SP is listed as about 25 minutes longer than just plain concrete (5:05 with 1025SP versus 4:40 for plain concrete).

Something really doesn't seem right with your results.

Unless you are The Hulk or some other superhero, you shouldn't be able to make a thumbprint in 7 day old poured concrete.

I could see the pics with the "i." in the url, then I took them out and they disappeared. I put them back in and I still can't see them. But I can see the ones in kTHREE's post!

 

[tarmy]

Something ain't right...

There is no way that should be that poorly mixed...pliable and basically no good.

If it was me...I would start over....

1 day for intial green set, 1 week for about 85-90% strength...28 days for full set.

Forms on for a week if structural build...strip and don't load till 29 th day....

You either got bad material, over saturated it to the point of washing all the concrete out...or the additive reacted with something in a bad way...

 

[Mr_B]

looks poorly mixed and with cavities and roughness was too dry .
I don't touch ready mix as it junk compared to mixing your own with either ballast or sharp sand, chippings and decent fresh cement .
Be careful with plasticiser in concrete as can cause lot of problems especially when higher amounts added.

 

[TractorJeff]

It looks like a dry mix!
That is the bad part of premix bags, one good one bad one good one low on concrete, they add up!

 

[bob15]

What exactly was used (have a picture of the old bag)? I ask because pictures show zero aggregate and the hundreds of bags of ready-to-mix bags I've used, I have never seen one without aggregate.

Do you use this:

or this:

 

[ford33]

That looks dry. Possibly not mixed sufficiently or had inadequate water content.

Sorry to say you many need to start again.

If you hit it with a hammer, does it fall apart?

 

[fritz4545]

Each bag of quikrete (80 pound) contains about 12 pounds of cement, the balance is sand and gravel. The admixture dose rate on the spec sheet is for 100 pounds of cement, your way over dosed. Use 1/2 to one oz. per bag and it should work.

I would not use the block that you have casted, overdosed admixture can to strange things to concrete.

 

[FTG-05]

What exactly was used (have a picture of the old bag)? I ask because pictures show zero aggregate and the hundreds of bags of ready-to-mix bags I've used, I have never seen one without aggregate.

Do you use this:

or this:

The second one.

 

[FTG-05]

Each bag of quikrete (80 pound) contains about 12 pounds of cement, the balance is sand and gravel. The admixture dose rate on the spec sheet is for 100 pounds of cement, your way over dosed. Use 1/2 to one oz. per bag and it should work.

I would not use the block that you have casted, overdosed admixture can to strange things to concrete.

Here is what the SDS says for dosage:

"Dosage: MasterPolyheed 1025 admixture has a recommended
dosage range of 3 to 12 fl oz/cwt (195 to 780 mL/100 kg) of
cementitious materials for most concrete mixtures. A dosage
range of 3 to 5 fl oz/cwt (195 to 325 mL/100 kg) is typical for
Type A applications and up to 12 fl oz/cwt (780 mL/100 kg) for
mid-range and high-range applications."

So the dosage rate applies to the cement amount, NOT the concrete mixture?

Well the good news is if this is true, then we have a cause that is easily fixed. The other good news is that it appears the concrete will eventually cure since the top has turned grey and is fairly hard. Good thing I don't need it for a while.

Thanks,

 

[FTG-05]

And what's the deal with the pictures? I'm using Imgur since PB crapped the bed.

Don't tell me i gotta go find something else!!!

 

[FTG-05]

Each bag of quikrete (80 pound) contains about 12 pounds of cement, the balance is sand and gravel. The admixture dose rate on the spec sheet is for 100 pounds of cement, your way over dosed. Use 1/2 to one oz. per bag and it should work.

I would not use the block that you have casted, overdosed admixture can to strange things to concrete.

It looks like this is the problem. I looked up other SPs data spec sheets (e.g. ADVA 555) and they clearly state:

Recommended Dosage Rate: 8 to 20 fl oz per 100 lbs. Cement Weight" (emphasis added). See here: http://www.buddyrhodes.com/water-reducer-adva-555/

 

[FTG-05]

Anyone know how much cement is in a 60 lb bag of Quikcrete Sand/Topping Mix?

The SDS sheets says "10-30% by weight. That's somewhere between 6 and 18 lbs.

Thanks,


Oops! for got to leave a link: https://www.quikrete.com/productlines/sandtoppingmix.asp

 

[kTHREE]

And what's the deal with the pictures? I'm using Imgur since PB crapped the bed.

Don't tell me i gotta go find something else!!!

You have to strip the https and drop the "i." to embed.

"https://i.imgur.com/bFHlEn6.jpg"

Becomes ->

"http://imgur.com/bFHlEn6.jpg"

Just replace the "" above with

and Bob's your uncle.

 

[kaymccampbell]

What did you mix that concrete in? It looks like it was dumped dry in the form, supplied with insufficient water and stirred with a teaspoon.

 

[pancho400cid]

You have to strip the https and drop the "i." to embed.

"https://i.imgur.com/bFHlEn6.jpg"

Becomes ->

"http://imgur.com/bFHlEn6.jpg"

Just replace the "" above with

and Bob's your uncle.

Great info. Thanks...

now back to the topic......

 

[joes169]

A couple of things:

- Pretty much any admixture (plasticizers, chlorides, accelerants, color, etc..)works off of the cementicious weight, not the total concrete weight.

- It sounds like you used the same amount of water as without the super P? That really negates the use of the super P. Your slump must have been approaching 10-11", aka soup.

- Sand topping mix is the wrong product for this, even standard Quikrete has small stone this is less than optimal for this thickness.

- Almost all Quikcrete products are lean on actual Portland cement and can benefit from a little additional Portland added to each bag.

 

[Lassen Forge]

It's hard to tell, but it looks like your mix is shy on aggregate to me, plus you may be heavy on the super P. Also are you mixing in a power mixer or using a shovel and tray?

Quikrete is pretty failproof stuff normally - you may have to start over.

Good luck!

 

[LX-Markham]

Absolutely have to start over. That's not concrete. You got yourself wet sand there.
Something wrong with the bags of quikrete you got. Doesn't look like there was any cement in the mix.

 

[Strouty]

Since when is a superplasticizer a retardant? It is to help flow of the concrete while reducing the water content.

Regardless, that is not concrete, it either wasn't mixed or there was an issue with the bags.

 

[gsmith22]

super p has a slight retardant-like effect where the mix will stay soupy longer than it otherwise would without the super p. But look out, because when it starts to set, it will go off quicker than you realize. It is why super p isn't great for everything (walls/columns yes, slabs not so much) and there are many variations of water reducing admixtures to combat this tendancy. Super p is the high range water reducing admixture. for a slab or something with large exposed surface where visibility is concerned (ie, you want to trowel and finish it) a low or medium range water reducing admixture is probably better. Other admixtures can be added to combat the retardant affect of super p as well so it is rare that it is dosed in isolation anyway.

 

[Strouty]

I guess, but adding more water to a mix has a retardant effect, but I would never call water a retardant for concrete.

 

[Strouty]

The only reason I would ever use superplasticizer is when I want a strong mix, while allowing for a higher slump so I can move it easier. Most knuckleheads just add more water, but it is really easy to turn a nice mix into ****, then you lose all the strength. I don't know that I have ever used a retarder without a WRA, so it may be confusing people, or I could be the confused one.

 

[gsmith22]

retardant is probably a bad way to describe what super p does. It doesn't elongate the hydration process - it keeps it soupy longer initially and they sets it very quickly. However, the overall timeframe for setting remains the same. A true retardant would actually extend the timeframe and the set would take longer (all other things being equal).