Fully Burned Brick

There's a sure fire test. Use the bricks to build a large arch. Stand under the arch as you disassemble the forms used to construct the arch. If the arch is self supporting you can feel confident the bricks have been fully burned. Should you notice that several of the bricks are raining down upon you you might consider firing them a bit longer.

i've tried that, but only once.

Are you asking about the difference between a fire rated brick and one used in standard building construction? Fire bricks are typically made of a slightly different material, which will not crack/explode when heated to extreme temperatures. A non fire rated brick will have small air pockets in the material which may contain small amounts of trapped moisture (from the clay it was created). When these bricks are heated the gasses/moisture inside the small pockets will expand and cause a failure/rupture of the brick. Fire rated bricks will remain stable when heated, and will not explode or fall apart. Fire bricks are typically a bit more expensive, not as rough, and (usually, at least from the ones I've had) are not as "red" as the standard bricks, mine appear to be a bit more on the "grey" side.

I'm not a brick Guru, but I have had a few of both bricks through my days... I know first hand that a "standard construction brick" does not work well to contain large amounts of heat.

Burnt brick is ""Brick that has been treated in a kiln at an elevated temperature to harden it, give it mechanical strength, and improve its resistance to moisture""

yep... there I go again misunderstanding the post...

A brick with water still in the clay have to have a resistance to it, similar to a wood moisture meter. Fully burned ceramic is an isolator. You will need to experiment on details.

What are the harmful effects if bricks which are "not fully burned" are used?

The structure comes down on someone's head.

check the uniformity of colors and texture of surfaces of bricks...from the common sense you can deduce which one is burned and which one is not..sounding also can work, as the properly burned one gives out a sharp sound over the rest,again you can use water,just splash on the brick u are not sure of,and try to feel the surface using the finger,the one getting a soft consistence is not properly burnt,proper burned one dont respond on...the efect of using unburnt one is missing of benefits if u would use the burnt one..low strength,much affected by weather(rain,humidity,etc)...etc

a fully burnt or fired brick should be equally hard on all six sides. chipping at the sides with a rock hammer should give you and an indication of it's hardness. some older brick have only one hard face that were laid with the hard face towards the exterior.. weather will deteriorate softer brick in a short time.

I am not an expert but I am curious if you could simply break the brick and look at the inside? Maybe some one here can say if the break line would appear different in color and texture as the outer edges are compared to the core. Or if the broken face would give off more dust when scratched with a screw driver or something similar. Again I do not know if these tests will work. But, it seems that if there is a difference in strength then these or some similar tests should tell you some thing. They at least sound safer than standing under a a newly built arch and waiting for them to fall.

Or you could send a sample to these guys https://www.brickandtile.org/testing/

Found this site for field testing bricks and it covers some of what I thought and much more. I hope it helps. http://practicalaction.org/practicalanswers/product_info.php?products_id=239

I forgot to mention that my thoughts on breaking a test brick were to check a lot quantity or pallet. It was not my intent to suggest you break every brick in question. Although you could reserve the destructive testing for the cut bricks when either starting / ending a course, windows, doors, or working around plumbing or vent piping. The last web site link in my original post has some test suggestions that would not damage the brick beyond its usefulness. Scratches in its surface that would be hidden by mortar would not be seen by the person you are building the wall for.

If the bricks are not fully cooked, they can fall apart as the water inside will wear away the clay.

So not properly fired bricks will damage the structure being built, and then you will be in problems.

As to knowing when they are well fired:

1.- Buy only from reputable sources

2.- Make sure there is a warranty for bad workmanship or quality of the Bricks

One way to see if bricks are well fired, is to take samples from batches received, break them and confirm that it is uniform, that they have no porous patches or bubbles.

i can't help to wonder how the manufacturer would resolve a warrenty issue, but i'ld think the victim would be royally screwed.

ISO 9XXXX system.

http://en.wikipedia.org/wiki/International_Organization_for_Standardization