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Heading: 1.1.2.1.2high 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


I should also mention that's just a std mix design with a minimal amount of the admixture that survived to over 460 degrees. I've also seen add'l studies (didn't participate, just reviewed) where with some commonly available add'l materials and higher concentrations of the admixture the survivable temperature resistance rose to thousands of degrees. The key appears to be in the ultra micronization of any remaining moisture within the hydrated concrete. Particles of H2O are too small to boil, also makes the concrete extremely freeze resistant. I regularly torch a corner of a six inch cube to over 700 degrees with a cutting torch while pressing my thumb onto the opposite corner. The heat resistance and lack of conductivity is unreal. To complete the demo, drop the superheated cube into ice cold water. No damage.
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George Clark
 
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