[ggano]

There is a recessed area (approx 3" deep) in the concrete slab in our bath that I need to build up before I install an acrylic shower base. I plan to use Quickcrete mortar to build up this area, then level off to match the height of the surrounding slab floor. The total area that I am building up only measures 3'x3'.

The shower base manufacturer also recommends setting the base into a 3/4" to 1" bed of sand topping mix to provide extra stability. So my questions are this:

1. How long do I need to leave the Quickrete mortar mix dry before I can overlay with the sand topping mix? One day? More?

2. Quikcrete states that the sand topping mix cures in as little as 30 minutes. Does tis mean that if I wait an hour or so, then I can stand on the acrylic shower base without any issues?

Just want to make sure I do this project the right way from the beginning. Tks for anyone's input.

 

[dj3]

Most concrete mixes can be stepped on in a couple of days, but it really depends on the weather. There are some mixes that are treated with an agent for a quicker drying time, but concrete reaches its full strength in 28 days.
For your purpose, wait 2 days without disturbing the concrete, it won't cure in 2 days, just be ready for sand topping.

 

[Missouri Bound]

1. How long do I need to leave the Quickrete mortar mix dry before I can overlay with the sand topping mix? One day? More?

You do NOT want to use mortar mix. You need CONCRETE mix.
Mortar mix is a material used for thin applications.
The instructions on the bag will tell you how long to wait.
You really don't have a high stress installation so cure time isn't as crucial.
The best indication of when it's ready is the color. When it stops looking green you are getting there.

 

[ggano]

Thanks very much for both replies. And yes, I meant to say Quikcrete concrete mix for the bed, not the thinner mortar mix.

 

[stadry]

you can walk on 3" conc in 24hrs w/o leaving dents or cracks,,, set your pan in 3 days if you must,,, otherwise wait a week