Can concrete dust explode ? 4

[Bob167]

Mechanical engineer requires advice with chemistry problem !!

Is it possible for fine concrete powder, any size, any concentration (generated by crushing during demolition) to ignite in dry air ?

Any info welcome.

 

[jheidt2543]

This is only a guess, but I would say yes, just as the fine dust in a grain mill or gypsum plant can. To get a definitive answer, I would call the Portland Cement Association (PCA). You can get the number from their website .

 

[Bob167]

Thanks jheidt2543,

I understand that the large ratio of surface area/ volume is a significant factor in dust explosions, but I presume that the molecules of the particles would have to be capable of combining with oxygen to enable combustion to start. Unfortunately, my knowledge of chemistry isn't quite up to it !!

I tried 'google' but couldn't find anything definite so, thanks for the tip; I'll contact them direct.

Regards,

Bob

 

[flamby]

I don't think any part of concrete - cement or aggregates are combustible. Finely crushed concrete is just like clay or dust. Can become red-hot and sparkle, if heated, but will not burn.

 

[Bob167]

Thanks Flame,

That is very reassuring; and other sources give similar indications.

I didn't pay enough attention in chemistry lessons, so I'm glad that you guys stayed awake !

Regards,

Bob

 

[ubrales]

No, concrete dust will not ignite or explode - in fact, might be a good flame retardant. On unknown dust concentrations, I would flame test a small sample in a controlled environment. Check to see whether a chunk of the parent material will burn at different temperatures.

 

[Bob167]

Thanks ubrales,

That is very positive. We are trying to figure out the best way to clean a contaminated concrete surface. The work must be done remotely so the prior testing of samples would be difficult - but not impossible. Thanks for the advice,

Regards,

Bob

 

[miningman]

I would have thought its virtualy impossible . We do have problems underground with sulphide dusts expoding but it takes some almost unique minerology to get this effect. When it does exist we use lime or calcuim carbonate to quench the flame front in the first few milliseconds after ignition. Cement and concrete being based on limestone should have the effect of reducing the likilihood of other dusts igniting.

 

[Bob167]

Thanks miningman,

I think that I am fairly confident now. One problem with concrete is the (unknown) chemical composition of the aggregate.

If lime products are capable of killing a flame then even the ? possibility ? of a potentially flammable component is not a serious risk.

Thanks for your contribution,

Regards,

Bob