Bottom ash as base course and long term stability?

[oldestguy]

A local highway has had bottom ash used on an experimental basis as base course for about 18 years. It may be the cause of winter time excessive joint heaving that seems worse each year now. When installed it met gradation, soundness and wear specs, but had no tests for frost susceptibility.

Any body have long term experience using it for similar use?

Can it take repetitive loadings under flexible pavement?

 

[concretemasonry]

Bottom ash is a waste product that has no specifications or control over the variability. Because it is very brittle it may break down because of weather ot loading over time.

The properties can vary daily, weekly, monthy or annually depending on the fuel and the operation of the facility producing it. One or two tests of the original product would not mean much.

It was probably used because it was cheap or locally accesible.

 

[JML4TCM]

Bottom ash can have high levels of chlorides and sufide that could create acidic environments, like Pyrite. Depending on the bottom ash it may react to water.

In my opinion, you get what you pay for and bottom ash is often free.

 

[fattdad]

Bottom ash is likely to be just fine and can provide LEEDS credits, which can be an advantage to the owner. Bear in mind that variability and reactivity are important items to consider. Also, bear in mind that you should only consider the use of "Bottom Ash" and exclude "Fly Ash" or "scrubber residue" in civil engineering applications without extensive testing on potential mineralizing swell.

DO NOT BLEND THE BOTTOM ASH WITH LIME KILN DUST IF THERE IS ELEVATED SULFUR CONCENTRATION.

f-d

¡papá gordo ain’t no madre flaca!