The additive that is put in papercrete to replace part of the cement is fly ash. It is so fine that it acts as a pozallan - an additive to cement that makes the cement more pliable and easier to spread. The main reason is to reduce costs.
<http://en.wikipedia.org/wiki/Pozzolan>
<http://en.wikipedia.org/wiki/Fly_ash>
I think we are confusing two groups of very different waste products. Both clinker and fly ash are byproducts of coal combustion, but there the similarity ends. Clinker ranges in size from that of a garden pea to chunks two feet long or more. Fly ash is so small that it flies up the smokestack. I believe the clinker acts like an aggregate in the usual cinder block. The fly ash actually acts as a binder, like cement but not as strong. The lucky happenstance is that up to 50% of the cement in a concrete mix can be replaced by fly ash without reducing the strength of the concrete. While cement is inexpensive, fly ash is even cheaper.
Wood ash and rice hull ash are both the result of combustion of organic material. Rice hulls are unique chemically and physically. So we cannot assume the wood ash will have similar properties to rice hull ash.
You have an idea that is worth testing. I believe that you cannot assume wood ash will have equal proprieties to rice hull ash. I feel you should test and compare wood ash modified papercrete to "normal" papercrete and urge you not to use it for buildings for humans until you have tested it.
Bobby
---In papercreters@yahoogroups.com, <rustaholic777@...> wrote:
Cinder Block was properly called cinder block.
For example, We used to have a coal fired power plant here in town so they had coal cinders. The Concrete Service is the company here that has been making blocks for a very long time. Back when they had free coal cinders they also made a line of lighter Cinder Blocks. They are a much darker gray color and weigh less. Anyone that looks at them should know the difference. Still way too many people even in books and on television are calling cement blocks by the wrong name.
Alan in Michigan
From: "domemancpf@..." <domemancpf@...>
To: papercreters@yahoogroups.com
Sent: Friday, November 22, 2013 3:16 PM
Subject: [papercreters] RE: screened wood ash added with cement?
Hi Jackie !
Being old school cement block were called cinder block so i assume a good portion or the block was made from cinders= ash . Also ash is very alkaline like lime so chemically similar too . Best way is to try a small batch a see for yourself u may be pleasantly surprised ! Conrad
---In papercreters@yahoogroups.com, <diggingfortreasure@...> wrote:
Here is another question I have about possibly cutting down on cement powered. I've read that some people add coal ash with the cement powered up to 1/3 without harm. Has anyone ever heard or tried using screened wood ash in the same way?? Does anyone think this could be possible without harming or weakening the papercrete???
Jackie
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