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</o:shapelayout></xml><![endif]--></head><body lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='color:#1F497D;mso-fareast-language:EN-US'>Dear Michael<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='color:#1F497D;mso-fareast-language:EN-US'>How’s things on the island?<o:p></o:p></span></p><p class=MsoNormal><span style='color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><div><div><div><div><p class=MsoNormal><span style='color:#1F497D;mso-fareast-language:EN-US'>></span><span lang=EN-US style='font-size:12.0pt;color:black'>there is a growing body of information on fly ash cement.</span><span lang=EN-US style='font-size:12.0pt;color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>It has become more popular as a way of cutting the price and using an otherwise waste pile next to power stations.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Fly ash (coal ash) is ground to micron size and mixed with Ordinary Portland Cement which is itself a mixture of dehydrated lime and clay.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>It is usually sold with the fly ash content on the package such as “30%” (by weight). <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>It cures more slowly than OPC and can be stronger. It is however still a hydrating mix (sets with addition of water which is absorbed and converts the lime back into limestone).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>></span><span lang=EN-US style='font-size:12.0pt;color:black'>With a fire resistance up to 1200 degrees has any one done <o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'>any serious work with it for rocket stoves? <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Well there I have to pause to think. Are you referring to fire clay cement? Fireclay cement can reach that temperature but there are a couple of types.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>The point I thought I would make is that the hydrating portion of high temperature cements burns out above 400C. That is why I was wondering about the mix.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Maybe you have read about a cement made entirely (almost?) of fly ash because that would be something that could ‘stick’ as it melts at high temp. The ash melting temperature (which is not a single point – there are lots of things in there) could be maybe 1000-1300 which is in the range you mentioned.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:#1F497D'>></span><span lang=EN-US style='font-size:12.0pt;color:black'>Sounds like a mix of fly ash cement with perlite might make a very <o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'>good 5 gallon gallon rocket stove.<o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'> <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>As long as both the filler and cement can take the temperature. Walls can get to 800 C on the surface pretty easily. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:#1F497D'>></span><span lang=EN-US style='font-size:12.0pt;color:black'>I did see one reference to an elbow for a rocket stove. If that is effective <o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'>the boxes beach sand wood ash bucket etc could end up making rocket stove truly<o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'>easy to make.<o:p></o:p></span></p></div></div><div><div><p class=MsoNormal><span lang=EN-US style='font-size:12.0pt;color:black'> <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>If the beach sand is lime-based (coral) it will also burn out above 400. Your solution seems to be to import (or dig up from the ocean floor?) some clay.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>What is in fish bone ash? Is it silica?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='color:#1F497D'>Crispin far away<o:p></o:p></span></p></div></div></div></div></div></body></html>