Frost Protection for Slab 1

[delagina]

I'm not the original Engineer this detail was already done but we have similar foundation.

I have questions with the way the slab/grade beam was detailed for frost protection.
The grade beam is ok because it's below frost depth.
The slab is not connected to grade beam, it has isolation joint.
Is the slab protected against frost in this detail shown below.

 

[msquared48]

Is the slab inside or outside?

Outside, unless the joint was sealed, I would say no, but inside, yes.

Mike McCann, PE, SE (WA)

 

[delagina]

slab is outside, unheated.

soil report recommend, "for slabs with turned down walls extending below the frost depth, no outside wall treatment is required"
my understanding with that though is slab needs to be doweled to wall/grade beam?

anyway, what's the best way to correct the detail.

 

[jayrod12]

even if you were to connect it to the wall the slab will still want to heave due to frost. If you are trying to stop this from moving seasonally then you'd need to install the appropriate amount of insulation below the slab.

 

[delagina]

Soil report only recommends 12" of non-frost susceptible material which was provided.
I guess this detail is good.
It has a grade beam/wall below frost depth and a slab with 12" of non-frost susceptible material.

 

[Splitrings]

It takes three things to create a frost heave: extend periods of temperatures below freezing, a frost susceptible soil and a source of moisture (infiltration, capillary rise, etc.). If you have all three and frost penetrates deeper than 12” annually, this slab will heave.

 

[spats]

This document may help...

http://www.toolbase.org/Design-Cons...sign-Guide-Frost-Protected-Shallow-Foundation

 

[Jerehmy]

yes it will heave without insulation since it's an unheated building.

I recommend SEI/ASCE 32-01 Design and Construction of Frost-Protected Shallow Foundations. They have a situation where you have a slab on grade in an unheated building with foundation walls.

 

[oldestguy]

How's come some come to believe that concrete is an insulator? It's a damn good heat conductor. Another thing, "frost depth" varies due to many factors. We are lucky these rough rules usually work, but not always.

 

[TehMightyEngineer]

Oldest, I think people often confuse thermal mass with insulation values.

Maine EIT, Civil/Structural.