Concrte steps
Concrte steps
(OP)
Some newly placed concrete steps were made with the treads only 11.5" wide. These steps comprise 2 risers and 1 tread, and are located at intervals along the landscaped walkway. The walkway is the main entrance and exit to a place of worship. It is wanted now to increase he tread width to 14".
Attached are three options that I have come up with for making the reinforced concrete tread 14" wide. Each seems to me to have its pros and cons, but I am particularly interested in your comments on Option 3 (drawing SK-3). Can the concrete be cut back as I have shown? My reservation about that option is that it would be necessary to chip out at least some of the concrete and this would leave a rough surface; also the existing rebar ends would be exposed; also the sawcut would leave a sharp corner at the top of the riser.
Option 1 is likely the most economical, but it leaves the overhanging concrete subject to frost heave. Similar frost heave issue with option 2.
Anyone have any other way to make the 11.5 inch wide tread 14" wide?
(I was not involved in the design of the steps. It was done by a landscape architect. After it was built a number of people in the congregation questioned the tread width, and one person fell within a week of opening the walkway to use).
Attached are three options that I have come up with for making the reinforced concrete tread 14" wide. Each seems to me to have its pros and cons, but I am particularly interested in your comments on Option 3 (drawing SK-3). Can the concrete be cut back as I have shown? My reservation about that option is that it would be necessary to chip out at least some of the concrete and this would leave a rough surface; also the existing rebar ends would be exposed; also the sawcut would leave a sharp corner at the top of the riser.
Option 1 is likely the most economical, but it leaves the overhanging concrete subject to frost heave. Similar frost heave issue with option 2.
Anyone have any other way to make the 11.5 inch wide tread 14" wide?
(I was not involved in the design of the steps. It was done by a landscape architect. After it was built a number of people in the congregation questioned the tread width, and one person fell within a week of opening the walkway to use).






RE: Concrte steps
RE: Concrte steps
RE: Concrte steps
Jim
RE: Concrte steps
Please try the second submission that I sent with attachment and let me know. It should open ok. The first attempt that I sent with attachment would not open for me either, but the second attempt would although it took a while to open.
RE: Concrte steps
No. 3 will show rust at the cut off bars and how do you get s smooth cut for the horizontal cut flush with tread? Perhaps with a concrete cutting "chain saw", but difficult.
RE: Concrte steps
I had not thought of bonding paste for option 1, but I can add that to it. One thing about option 1 is that there could be frost heave force exerted on the overhanging part, which leaves me a little uncomfortable. To excavate it down 4 feet though would be a significant cost.
RE: Concrte steps
Jim
RE: Concrte steps
I also like Option 3 but it'll be a bit of a pain since the concrete has to be cut out with a chop saw or line drilled. You can grind it for a smooth surface or over cut it a bit and put in a new facing on both surfaces. It could help with preventing rust stains from coming through.
RE: Concrte steps
RE: Concrte steps
You won't be able to cut 3 well. 1 is too small to do properly IMO.
When I am working on a problem, I never think about beauty but when I have finished, if the solution is not beautiful, I know it is wrong.
-R. Buckminster Fuller
RE: Concrte steps
RE: Concrte steps
RE: Concrte steps
To dcarr82775 - I had thought of both the ideas you suggest to relieve frost heave, but was not comfortable with either of them because the pavers might eventually drop down due to settlement of soil supporting the pavers into the void; there is no slab under the pavers. Angling the projection is a way of improving things, but again it would make compaction of the soil more problematic and adfreeze forces might still result in uplift force, but I will give it more thought. Thanks.
I assume that no one sees any options other than the 3 that I have suggested?
I don't know what the problem is with opening the attached file. Although before I could open it, now I cannot! I wonder if something has gone wrong with the Engineering Forum software...are you able to upload and open any of your pdf files created with Bluebeam?
RE: Concrte steps
RE: Concrte steps
The building Code applies to the building. The exterior landscape steps are not covered by the building code, being as they are well outside the building. We confirmed this at the outset, with the building department, and a thorough search of all building code provisions pertaining to steps. However if they were covered by the building code, there is nothing in the building code against a 14" tread. Although not covered by the building Code, the general rule is the wider the tread, the shallower the riser should be.
To oldestguy: Styrofoam is not very compressible, certainly not enough to absorb frost heave. We never use styrofoam when we are looking for compressibility. The beadboard is more compressible, but of course that will take up water so is not acceptable, as you have noted.
RE: Concrte steps
For what it is worth I just took a 2" square section of 2" thick pink stuff and squished it to 1 inch height. It moved up to 22 psi on the way and then leveled off at 30, and then dropped gradually. Removed load and sample returned to 1-3/4". Ran several more cycles to 1" and return generally to the 1-3/4 mark. In the process of sitting at 1", each time the load dropped off toward the 22psi level. Thus, I'd not be too unhappy with a, 8" stack of pink stuff under the new extension. How much lift is common there with current pavers?
RE: Concrte steps
Your tests are quite interesting...did you do that in a lab?
What do you mean by "the pink stuff"? Dow Type SM insulation (in Canad, or Dow 35 psi insulation in the U.S. I believe), is what is usually used here in Toronto, except under pavement with vehicle traffic, in which case the HL40, HL60 or HL100 would be used, depending upon the stress on the insulation. A pink stuff is made by Owens Corning, and like Dow, they make several different grades, but is identical to the corresponding Dow grade...at least that is what Owens Corning told me a number of years ago! Which grade of the pink stuff do you have, and is it the Owens Corning product?
You say that it moved up to 22 psi and then leveled off at 30 psi. I am confused. Do you mean it moved up to 30 psi and then leveled off at 22 psi?
RE: Concrte steps
The stuff is Owens Corning FOAMULAR 250, commonly used for house insulation board. Extruded Polystyrene (XPS). I use it for covering my hot tub after the beaded stuff soaked up water.
I ran another test this AM and recorded the data. I then put it on a spread sheet and could have printed it or sent a file. However, here is a photo of my screen.
At the top of the load, as the deflection was reached and held, the load dropped off. For instance, the 0.875 deflection load of 110 dropped off to 100 pounds and still moved but more slowly. The 0.50 inch deflection went back to 0.25 inch and the 0.75 inch deflection dropped to 0.375 after each load removal respectfully.
It would appear that a form of "spring effect" is present so permanent deflection won't happen leaving a place for snakes, etc. under the step.
While this compression load capability is pretty good, I'd suspect the total weight of the step system is such that frost heave won't lift anything. Of course that bond and reinforcing must hold. That Portland cement paste thing is great. I have taken cores of a joint of old and new concrete and then take a chisel to that bond and the break is always in concrete away from the joint. The reason appears to be due to the dry concrete taking in the cement in pores there.
RE: Concrte steps
RE: Concrte steps
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RE: Concrte steps
I see on the sheet it says "moisture resistant". It indicated a link also.
www.foamular.com
when I went there I think your answer is here.
http://www.foamular.com/foam/products/foamular-250...
That confirms my experience.
RE: Concrte steps
If the concern is the 250 strength, and even the 150 is too strong, consider pourable foam from mixing two parts. .
It came up under a search for Two part closed cell foam. Apparently this product is closed cell (for floatation), but I didn't see strength properties
I have used these foams to fill large cavities for a catamaran as well as the electronic transmitter-receiver filter for a ham radio repeater station.
http://www.fibreglast.com/product/2_Lb_Polyurethan...
RE: Concrte steps
RE: Concrte steps
RE: Concrte steps
Careful when testing small samples and projecting the results to large pieces. Edge restraint conditions can skew the results of the smaller sample to give greater apparent flexibility than would be experienced by the large piece. Think of perimeter to area ratio. Also see calculations for elastomeric bearings.