Recommendations on a thin topping slab 1

[hnazir]

My company is currently designing a difficult vaulted sidewalk project that will affect concrete due to several constraints; I am interested to hear any recommendations that you may have on this. The vaulted sidewalk project is currently in the design phase, and due to limitations regarding existing building conditions / elevations and the location of the project in an extreme weather environment, we are seeking advice specifically on a the topping slab concrete.

Our first constraint is the allowable thickness of the topping slab. For the other locations of the vaulted sidewalk we are able to construct topping slab with 4-inch thickness, but the conditions at one particular location constrains us to a maximum of a 2-inch thickness topping slab. This topping slab will also be constructed over thicker structural slab with a waterproof membrane laid over the structural slab and underneath the topping slab.

Our second constraint is the extreme environment. The project location is in Butte, MT, with an elevation at the job site of 5700 ft. Butte also experiences very cold conditions for much of the year, for example Butte’s high temperature for this Friday (Jan. 11, 2013) is 17°F and a low of -1°F. We will not be constructing the project in these conditions (scheduled for spring/summer), however with such a thin topping slab, harsh winter conditions, and associated deicer applications, are bound to have adverse effects on the topping slab.

We would like to hear any recommendations as far as mix design, additives (such as fiber or chem), jointing vs. the allowable spacing, and anything else that may help.

Attached you will also find a representative photo of the vaulted sidewalk replacement as well as a hand drawn sketch to give further detail of the design.

Thank you for your recommendations,

hnazir

 

[JedClampett]

I'd talk directly to a manufacturer. Atlas is pretty responsive. But there are any number of good ones.

http://www.atlasform.com/pages/concrete chemicals and repair materials.html

 

[Ron]

In addition to JC's recommendation, I would suggest that you consider short, ductile steel fibers. I would not use polypropylene fibers. Also, polymer modification to the concrete would be good as this will provide greater ductility to the concrete. Check with Sika on a polymer concrete mix.