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I'm having a hard time finding the "working time" specifications for Quikrete 5000.

The Quikrete 5000 Data Sheet says "higher early strength", but I'm only assuming that means it will achieve a higher PSI sooner on the calendar, not that it will set up faster while working it?

I'll be manually mixing six 80-lb bags total, two bags at a time for a small concrete countertop project, using water at normal cold-water tap temperatures. The work will be outside under a covered area during cool weather (40 - 50 degrees F) on a dry, sunny day.

Any rough idea how much working time I'll have under these conditions? Similar working time as regular concrete?

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  • Not heroic where concrete is concerned, but I've never felt like high psi concrete sets up appreciably faster than low test. (Plus, it seems like your project is straightforward enough that working time shouldn't be a problem.)
    – Aloysius Defenestrate
    Nov 4, 2018 at 14:12
  • @AloysiusDefenestrate, so about an hour?
    – Sparky
    Nov 4, 2018 at 15:07
  • I'll defer to Fu-Tung Cheng on this one: "When planning your pour, assume that once you add water, you'll have about 30-40 minutes to mix, place, vibrate, screed, and trowel the concrete before it begins to set up." (p.105, Concrete Countertops, Taunton Press).
    – Aloysius Defenestrate
    Nov 4, 2018 at 16:47
  • @AloysiusDefenestrate, I read Cheng's books and watched his videos. His method uses his own from-scratch concrete recipe, which includes all kinds of chemical additives; nothing like standard pre-mixed bagged concrete. So I'm not sure about that being an accurate comparison. Quikcrete and Sakrete have their own countertop mixes, but Sakrete has published online that their 5000 psi product is suitable for countertops.
    – Sparky
    Nov 4, 2018 at 18:09
  • Agree that he's mostly working with homebrew, so maybe a bad example. Still, unless you've got a really complicated top, I don't think you'll have working time issues.
    – Aloysius Defenestrate
    Nov 5, 2018 at 4:17

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I did the pour today.

It was 50° F with about 80% humidity. It looked like rain so I mixed by hand in plastic tubs on tarps inside a garage.

Quikrete recommends 6 to 10 pints of water for one 80-lb. mix. I used exactly 7.5 pints for each bag, which gave me a very stiff mix that held its shape until vibrated.

I mixed four bags in two tubs and it took a good 20 minutes by myself just to get those two 160-lb. tubs mixed thoroughly enough using a hoe and shovel. Then I was able to completely fill 3 of my 7 molds with these two tubs. Filling, vibrating, placing mesh, and screeding these 3 molds took another 50 minutes. I was able to catch a long enough break to clean tools and tubs. Then I mixed the last two bags in one tub and finished the last 4 molds, which were smaller and already had rebar and mesh secured inside. This took another hour.

Short answer: I easily had over an hour of working time.

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