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Heading: 1.1.2.1.1.2.1.1high temperature resistant concrete
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How can we make concrete resistant to very high temperatures (hundreds of degrees) ? Can addition of nano particles help in this case?


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deepika goparaju


Certainly you could use high aluminous cement concrete with a variety of different aggregate types. With respect to increasing the working temperatures and extending the service life of portland cement concrete, there has been some work published on the positive results of vacumn dewatering the freshly placed concrete. I would suspect that the addition of nano particles would also help in this case, but have no specific knowledge of their application here.
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James Mross


sir,

can the use of thermal barrier coatings(yttria-stabilized zirconia ) on aggregates be useful to make the concrete resistant to high temperatures? Can these coatings bond with cement properly?
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deepika goparaju


Clever idea Deepika! It might well be worth the trials. While I don’t have any expereience with yttria-stabilized zirconia or any other coating on the aggregate for that matter, it might have potential and could offer very interesting results. Obviously there would not be any chemical bond between paste and the coated aggregate, but in refactory applications, that wouldn’t be an issue anyway. Your interest would be in the ceramic and mechanical bond. Acting as a thermal barrier for the aggregate could help. Have you considered using crushed and sized high-alumina ingots as the aggregate? That would preclude or reduce much of the differential thermal movement between aggregate and paste.
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James Mross


What temperatures exactly? And how much repetition of thermal shock? Our admixture has been proven to make concrete highly heat resistant/survivable. One test I've participated in took identical mix design cubes into a high temp oven. The untreated concrete destructed at just over 200 degrees celsius and the treated concrete cube survived at the oven's maximum of 460 degrees celsius. Is that sufficient?
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George Clark


George asked the key questions; what temperature and thermal shock. In general, what application?
Refractories and refractory concrete happens to be my old profession, till 1991.
The application will determine the composition.
I would be very surprised if the idea of coating with zirconia would help. And then, coating of what and what size aggregate?
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Boudewijn Piscaer


Sir,
It is a steel melting shop and the temperature at the slab vary around 200 degrees.Due to frequent exposure to those temperatures, slab is failing and now, the maintenance cost has become higher than the construction cost. so, we are searching for a solution.And about the zirconia coating on aggregates, mine was a very basic idea and i am still working on it.
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deepika goparaju


Thanks, now I understand it better. 200 degrees is nothing but thermal shock is. Though I am a concrete man now, I would go to simple fireclay brick with a good strength and a good porosity. Otherwise use high alumina cement and recycled refractory aggregate and air entrainment for added porosity = thermal shock resistance.
Talk to a serious refractory supplier near you and have them install it!
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Boudewijn Piscaer
 
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