Ramp to existing slab

[asixth]

Hi

I have a slab with a step which is to be transformed into a ramp for disable access. I have a typical detail I use for door ramp thresholds which is generally less than 50mm (2") using high strength grout.

When the step is larger, 125mm (5") would the ramp require reinforcement or will it attain durability using the high strength grout product.

My construction process is to scabble the surface of the existing slab, apply a bonding agent and then installing the grout to achieve the ramp.

Does anyone else have experience with this detail and is this a feasible solution? Will the grout be too expensive? Should I be using regular strength concrete and reinforcement?

 

[Andrewstructure]

I would use WWF (welded wire fabric) for shrinkage and cracking reinforcement. Also to be considered is the location. Concrete that is cast in cold climates usually has an air entrainment mixture added in to aid freeze thaw durability.

 

[ToadJones]

I recently did one of these at a church elementary school. I didn't trust any topping for a ramp. I had them cut out the existing slab and pour a new full depth ramp. It also provided nicely for sleeves to install a handrail.

 

[paddingtongreen]

I wouldn't use grout, in my mind, grout should be contained, as in between a baseplate and the foundation, it tends to break up if exposed. Having said that, there are products that can be feathered. I prefer to have them hammer out about a quarter of an inch of the concrete and then use one of these cement/dry acrylic polymer mixtures. They say that you can get by with cleaning and chemical etching.

A little more information here:

http://www.crownpolymers.com/articles/concrete_patching1of3_CPM11.01.pdf

Michael.
Timing has a lot to do with the outcome of a rain dance.

 

[CarlB]

You might have someone (architect/civil engineer) verify that slopes will be acceptable for ADA requirements.

At a doorway I'd think you need a 4' landing that is flat (less than 2 percent), then the ramp could be no more than 1:12, so 5 feet long for the 5" drop.

 

[hokie66]

I would cut into the existing at least 2", then use regular concrete with small aggregate, say 3/8" max. For a small area, no need for reinforcement. Agree with paddo that grout is not suitable.

 

[asixth]

hokie

cutting into the existing slab 50mm would essentially expose the reinforcement of the slab. Is that the intent. Will there be any issues with cracking of the concrete if no reinforcement is provided? The ramp raises 5" plus the 2" which is scabbled back creating an unreinforced section of 7".

 

[hokie66]

The existing reinforcement in the slab on ground is there for shrinkage crack control. The shrinkage has already occurred. Sawing it there just creates a control joint.

Reinforcement in the overlay ramp could be used, but I would instead sawcut it into sections about 1200 or 1500 square to attempt to control restraint shrinkage cracking. The most likely place it will crack is in the thin bit at the bottom, and reinforcement won't help much there.