Asphalt Mortar (Slurry Seal)

...."Slurry seal is a mixture of emulsified asphalt, crushed aggregate, water, and set-control additives such as aluminum sulfate and/or Portland cement. Slurry may also use a variety of polymers to enhance the toughness and tenacity of the finished mix. Which additives are used depends on many factors including location, condition of surface, and the type of surface. Slurry seal is a cold-mix paving system that can remedy a broad range of problems on streets, airfields, parking lots, and driveways."...

https://cpmamerica.com/slurry-seal/

..."Water-based latex paint can be specially formulated for asphalt areas and is available in many colors. This type of paint must be used if the asphalt has already been sealed with another type of paint, such as coal tar."...

https://www.hunker.com/12003554/types-of-paint-to-use-on-asphalt

Asphalt emulsion = bonding to base material and a means to provide a workable material and a surface compatible with the final seal applied over it. Emulsion is bitumen and water emulsified. Allows low temperature handling.

Aggregates = Volume and a grip surface and thickness (strength)

Portland Cement or Lime = Setting agent to reduce flexibility (avoid "shove" failure) and provide some bulk and some level of workability before setting.

Not sure that water is necessary addition, as already present in the emulsion and will become available when exposed to air.

Slurry seal would usually be used with fine aggregate and to temporarily rehabilitate a (road) surface before a thicker finish seal was to be applied. It can make up some minor irregularities, seal cracks to the pavement layer and ultimately create a good bonding surface for the chip seal top layer. Often it would also be used as the first coating on compacted pavement layer to preserve that layer for final coating.

To make it look like concrete colour, well I've seen all sorts of coloured concrete. You would probably need to dust the surface with cement to create a new surface, but then would loose the intended purpose for top seal coats, but I guess that your not building a road/street.

"..to temporarily rehabilitate a (road) surface before a thicker finish seal was to be applied.." Yes indeed, temporarily being the key point, because the stuff is useless without the 'finish seal'.

Our town council uses the slurry to 'temporarily' fill potholes that open up during the winter, ie before it is warm enough to apply the surface seal. Without finish, it lasts no more than a few days and is completely useless... Every car that drives over removes a little of it until it is gone. Simply a waste of material and effort.

A neighboring town has a much better method - they have brightly colored sandbags (must be very tough material) which they place in the potholes until the weather is fit for the proper repair to be done. You can drive right over these without damaging the bags - or your car. I have to wonder why methods that actually work don't catch on quicker...

A proper patch....

While 99% of every other trade in the industrialized world uses the average tape measure, ruler or digital yardstick,,,,,

These guys use the highly accurate, yet controversial heel to toe measurement system.

Nice.

Because, methods that often work better can't consume as much of the public dole as quickly as inefficient methods can.

Where do you think the saying, " one guy holding a shovel and five guys telling him how to use it " , came from ?

The OP used the term "slurry" and to me that implies "flowable" and is intended for the type of uses that I described.

Almost the same mixture, with less emulsion and much larger aggregate is quite suitable for pothole repair, but does need a couple of hours without traffic to properly cure.

There are some really good pothole treatments available. One was developed in South Africa and is available in 2' or 3' square sheets including the chip seal and bitumen and is applied directly over filled and compacted potholes.

There are ways to apply proper chip seal using a different emulsion, but that requires the council to hold different emulsion tanks and they are not compatible and will essentially caused separation if mixed, even at 0.1%. Most councils thus choose one and standardise on that.

The choices may be limited here by freeze-thaw conditions as well. At this time of year especially, we are going from a few C above zero to -8 C or even -12C at night every 24 hours.

Still it is a fact, what they did last week was a total waste. The 'slurry' looked about the consistency of what is shown in SE's video link, so not especially wet. They put a few shovels of it into the holes. They probably had a few hours without traffic as it was done between rush hour and noon. Three days later, all gone.

In the longer run, you would be better off to dig out all the pothole area, down to the bottom of the subgrade, fill in the enlarged pothole with concrete slurry up to to the bottom level of the surrounding asphalt, and place a new, larger asphalt patch to bring the level of the repair all the way up to the top level of the surrounding asphalt...

You might get ten to twelve years of service life for only double or triple the cost of the asphalt slurry solution...

We did, back when I worked for the County DPW, some thirty years ago...

Good day...great experiences and anecdotes...ideas.... but I still have the question regarding "What is the Cement-Lime for ??" Some documents say it's for "consistency", "control the breaking emulsion time", "control curing time"....

I could understand that...but...how ? what happen chemically since we understand the phisical-chemical phenomenon happen with asphalt, CPO & lime per se ???

Hello Lyn

Hello,

The emulsion is a mixture of water and bitumen that has been "emulsified" so that it doesn't separate. (Like mixing olive oil and vinegar to make a salad dressing)

When exposed to air, the water and bitumen "split" or "break". Normally the water absorbs into the substrate, or evaporates off the surface. Using cement/lime in the mix would absorb that water instead and start its own setting process. The set cement is less flexible than the bitumen and so would provide some means to achieve locally desirable outcomes.

These mixtures have been developed over decades and a little like cake mixture, you need the eggs, sugar, flour, butter and milk (and maybe some sultanas) with added heat to get the correct end result.

As I indicated before, most places would settle on one emulsion (or maybe a summer and winter option) and the combination of other additives in the mixture provide the properties of the end surface desired. They can adjust these ratios for the different conditions they face.

For instance, some use "sand" (<1mm) as the aggregate to create a skin maybe only 3mm thick while others would excavate a pothole, spray with emulsion, fill with 20mm aggregate and then flood with an emulsion/sand/cement slurry.

Standards for cement are well defined around the world and so local standard mixes can be developed and replicated batch after batch.

Thank you...with your comments & other literature I did read, I will start to make tests...the goal it's to apply it over concrete.

I will show you later the results.