[Stoves] brick making

[frank]

Dear Crispin,

This is no 'small' contribution and is exactly the type of info I am 
looking for -thanks!

One thing I am wondering about is if my spring tester is comparable to a 
'real' test. It seems like it should be but it would cost a lot to find 
out. Also we are not a 'certified' lab for doing this type of testing so 
I will just use it for research. But I think for < $1000 US it could be 
very useful in places making and buying bricks.



Thanks again
Frank




Crispin Pemberton-Pigott wrote:

>Dear Frank
>
>I am impressed by your approach and the simple method.  Very good. Remember
>to check and record the density and plot the crushing strength against the
>density.  If you use different mixes, keep different charts for each. You
>will learn a lot.
>
>I have something small to contribute, which is how to rate the bricks.
>
>Ratings of bricks are important to know if they will, when assembled, give
>you a wall that stands to an acceptable load.
>
>This is one approach, or protocol, that is something applied in
>certifying/rating bricks.
>
>Crush 12 samples and obtain the load carrying capacity in p.s.i.
>Ignore the weakest and strongest readings
>
>Take the other 10 and calculate the average strength (sum, then total
>divided by 10)
>That is the rating of the set of bricks, provided that....the weakest sample
>is not more than 20% weaker than the average.
>
>If the lowest crushing strength of the weakest sample (of the remaining ten)
>is lower than 80% of the average, you have to de-rate the bricks until the
>weakest one is at -20%.
>
>Taking your first 12 bricks as an example:
>290
>245
>254
>254
>279
>266
>248
>212*
>227
>315*
>242
>
>Highest = 315 and is disregarded
>Lowest = 212 and is disregarded
>
>Average of the remaining 10 = 230.5
>80% of 230.5 = 184.4
>
>All ten are within the range of 184.4 to 230.5
>
>Therefore the strength rating of the samples is 230.5 p.s.i.
>
>If your samples drilled from the bricks do not meet the p.s.i. rating the
>architect specified when calculated in this matter, it will not be allowed
>to be used. 
>
>The typical brick strength requirement for a load bearing wall in a house is
>7 MPa and is calculated in this manner at the SABS (South African Bureau of
>Standards).  Pavers for vehicular traffic 20 MPa and so on. The system is
>simple and can be used by ordinary builders and brick makers.
>
>Regards
>Crispin
>
>
>
>
>  
>

-- 
Frank Shields
Soil Control Lab
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frank at compostlab.com
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