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Proprietary Bag Concrete

Proprietary Bag Concrete

Proprietary Bag Concrete

(OP)
Looking for some unbiased resources that discusses the problems with proprietary bag concrete.

Some of our contractors want to exclusively use non-Portland cement concrete mixes such as Quikrete and Rapidset. A few engineers I know have an aversion to allowing non-Portland cement, but I have been unconvinced by their argument thus far.

"It is imperative Cunth doesn't get his hands on those codes."

RE: Proprietary Bag Concrete

What is the use? It makes a difference.
Quikrete uses portland cement for its concrete mixes. RapidSet uses calcium sulfoaluminate cement for its fast setting products.

For small applications of patching or similar, either would suffice. Weathering resistance is going to be higher with straight portland cement mixtures than CSA cement as CSA cements produce calcium sulfate (gypsum) in the hydration process.

Avoid CSA cements for exterior application because of durability issues.

RE: Proprietary Bag Concrete

(OP)
Therein lies my befuddlement - my colleague engineers have said no to non-Portland in all interior and exterior conditions (partial and full vert, overhead, and slab)!

One specific example of these was the demo of the middle strip of a one-way PT slab (interior) for a new stair. The edge of the opening had to be reinforced to transfer the stair loads to the banded PT runs and support the stair railing, etc - and then obviously poured back in place (about 2 cub.yards). We spec'd USCP HP bag mix, and the contractor decided they wanted to switch to Quikrete's high early strength, because of the most less stringent water requirements (I think the HP is 2.75 quarts/sack and the Quikrete was something like 4 quarts/sack). And - of course it is wayyy cheaper. Of sort of a side note, their labor was not very good at mixing the lower water USCP. They either had dry clumps or lean slop and didn't seem to give a care for adherence to the product instructions. Regardless of the bag mix, we were taking oodles of cylinders out of concern for workmanship.

Thanks for the info on the gypsum!

"It is imperative Cunth doesn't get his hands on those codes."

RE: Proprietary Bag Concrete

In my opinion, bagged concrete is for setting fence posts...nothing more.

RE: Proprietary Bag Concrete

(OP)
That is definitely a KISS-like response.

"It is imperative Cunth doesn't get his hands on those codes."

RE: Proprietary Bag Concrete

Bagged concrete is for hunters.

Mike McCann, PE, SE (WA)


RE: Proprietary Bag Concrete

I've used Kwikcrete for years for fence posts. Put in dry. No worries.

Also I used it for a leveling topping over an existing slab. Used to come in 60 and 80# bags. Latest is 50#.

Mike McCann, PE, SE (WA)


RE: Proprietary Bag Concrete

We use RAPIDSET CSA-based concrete in 60 lb bags, coupled with the manufacturer's dry admixtures (for set control and plasticiser), for concrete repairs. At about $25 per bag it is near 3 times the cost of Quikrete, but 50% less cost than BASF and SIKA's equivalent products.

One recent project using RAPIDSET involved detensioning 50% of banded PT tendons anchorages to remove large voids/rock pockets due to terrible compaction practices by the concrete crew for a podium slab. Using CSA-based cements enabled us to restress the tendons the same day, then destress the adjacent 50% of tendons, and repeat the process, in a total of 8 hours, and return to service.

Pre-packaged concrete has its place in 'structural concrete', but the site personnel have to be clued in on the water content, admixture use, and in the case of CSA-cement, set time!

DOT's around the US use CSA concrete for pavement and bridge deck repairs, typically 60 lb bags for small quantities, and volumetric mixers for larger volumes.

On the negative side of pre-packaged products, I recently saw a local project where a Sika concrete product in 60 lb bags was used for full depth slab replacement to a parking deck, on a per bay basis of 10'x30'. The contractor 'lost control' of site production with inadequate sized mix equipment, too much mix water, and too few site personnel, resulting in all sorts of shrinkage cracking.

RE: Proprietary Bag Concrete

(OP)
Contractors losing control of their water proportioning & mixing is a huge recurring issue, but they seem not to take ownership of it - tend to blame the material.

"It is imperative Cunth doesn't get his hands on those codes."

RE: Proprietary Bag Concrete

Boneheads!

RE: Proprietary Bag Concrete

If they can't measure the correct amount of water, I don't like their chances of doing anything else right.

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