Asphaltic Overlay 3

[dik]

We are looking for an asphaltic overlay topping to be added to the floor of an armoury. The existing concrete slab has a two inch asphaltic overlay. We are building the floor adjacent to the stairs approximately 2" to 0". It is not known what the original material is, but it may be a special asphaltic mix used 100 years ago for this purpose. Any suggestions?

thanks, Dik

 

[Ron]

dik...I would take a sample to a testing laboratory and have them do an extraction (remove the asphalt cement) and gradation (particle size distribution). This will tell you what you need to do to match the existing asphaltic concrete.

It is likely a very fine mix, similar to an asphaltic concrete base course or sand-asphalt hot mix. I assume you will have to place the mixture in a cold state; so you'll need to modify the mix to accommodate a cold-applied asphalt cement (solvent release).

 

[dik]

Thanks Ron, I've already suggested the lab approach. I suspect it's a fine mix that was well consolidated. I don't suspect that they had many 'special' additives a hundred years ago. I've got a querie into Parks Canada (they do a lot of restoration work). Any idea of what they may have used? The concrete deck was surprising; the specs called for a 300 psf design load and a deflection limitation of L/900... First attempt at modification, the only beam affected looked like it could have been a concrete beam or steel encased in conc. Turned out to be plain concrete... they missed the reinforcing else there wasn't supposed to be any... Glad the contractor was careful...

Dik

 

[BigH]

Could the overlay have been mastic?

 

[Ron]

dik...it was probably a tarry asphalt with sand mixed into it. Your right, not many additives then, but the asphalt wasn't well refined either...could have actually been a natural deposit that had no refining. Not sure where you're located, but those existed in the SW USA, the Carribean, and I'm sure other locations.

It shouldn't be too hard to duplicate the mix, but I'm not sure what your placement constraints might be. Will you have to place, spread, and compact by hand? If so, you'll either have to develop a solvent based mix, an emulsion based mix, or batch it hot in small quantities to move with wheelbarrow or the like.

There might also be a limitation on the use of solvent based asphalt due to the volatility and the initial odor.

 

[dik]

Thanks Ron, it's not a large volume, a yard at most. The location is Winnipeg, Manitoba, Canada. It's possible that the asphaltic material came from Ontario, or Alberta. I was thinking that it would have to be a hot batch with a binder to the existing.

Dik

 

[dik]

BigH:
The overlay appears to be an asphaltic 'concrete' type of material that was installed approx 100 years ago. Remediation is to correct for a slope at the stairs and to provide the appearance of restoration and not remediation.

thanks, Dik

 

[Ron]

dik..yes, hot mix would be better all around if you can place it. Be sure to prime the existing portland cement concrete surface and the interface with the old asphaltic concrete.

 

[Ron]

dik...had another idea. Any chance it might be like a "roof deck fill" material? That has been done a lot over the years in Canada. It is a mixture of asphalt cement and vermiculite or perlite aggregate. It is placed as an insulating fill for roof decks. There are still a few of those deck companies around. I know there are several in the Toronto area. Check with the roofing guru's at Trow in Brampton, Ontario. While that's a bit too far for them to go for a yard of material, they can probably offer some material insight.

 

[dik]

Thanks... there does not appear to be any vermiculite in the matrix, only fine stone/sand aggregate

 

[dik]

Bad week... almost a steady diet of crow...

BigH, just received the following...

The original product was identified as an emulsomastic, primarily a mix of cement, sand and an emulsifier. The cement and sand provided structure and the emulsion provide some flexibility. I believe it was a fairly common product after the 1st world war as the Armouries have lots of it.

The building was constructed around 1915.

Dik

 

[TalGed]

I would advice to use sand-asphalt mix layed on the top of existing if the surface is solid, actualy if it solid I would not bother mysef to chech what is there. You may use hot bitumen sraied with rate of 300-400gr per sq.m as a binder.
But pay attention to fact that the asphalt does not react good to oil and DPK wich may be used in this type of fasility.
The compaction of small area should not be a problem, you can use hand compactor eg. boumag 900 or so, it will require large number of "passes" to get to required compaction.

 

[TalGed]

I would advice to use sand-asphalt mix layed on the top of existing if the surface is solid, actualy if it solid I would not bother mysef to check what is there. You may use hot bitumen sraied with rate of 300-400gr per sq.m as a binder.
But pay attention to fact that the asphalt does not react good to oil and DPK wich may be used in this type of fasility.
The compaction of small area should not be a problem, you can use hand compactor eg. boumag 900 or so, it will require large number of "passes" to get to required compaction.