Mortar cracking during cure process

[Thor]

I'm currently in the process of building a huge outdoor fireplace and am having a problem with the mortar forming cracks within a few hours of application. The weather conditions have been hot and dry with temps. averaging in the mid 80's . Does this have something to do with the problem ?
I have been using Hi Bond and have been keeping my joints as small as possible.

[mjpliv]

The weather probablly has everything to do with it. The water in the mortar is evaporating or being drawn into the bricks too fast which causes it to shrink and crack.

Hose down the bricks an keep them covered out of the sun. Wrap completed brickwork to keep the sun off your work. Cool, damp days are the best for doing any masonary/concrete work.

[mjpliv]

copied from http://www.bia.org/BIA/technotes/t39.htm

Test for Wetting Brick - The following test is useful for determining the necessity of wetting brick prior to use:

A circle, approximately 1 in. (25 mm) in diameter, is drawn on the bed surface of the brick, using a wax pencil and a twenty-five-cent coin as a guide. Twenty drops of water are placed into the circle using an eyedropper. If, after 90 seconds, all of the water has been absorbed, wetting the brick prior to placement is recommended

[Thor]

mjpliv , thanks for the reply. I kinda suspected the blistering sunshine had something to do with it but wasn't sure. I'm not the smartest bear in the woods when it comes to masonary work. I have an extensive background with shotcreting in an underground mining enviroment.
Even shotcrete has a tendency of cracking when it dries too rapidly in some of the dry locations which are rare underground , usually it's damp and cool.
Oh by the way I'm not using brick , they're massive stones from an old mine , very unique in appearance and some of them are so huge that I can barely lift them into their places. This project has had very many ooooohs and aaaahs from people passing by. Total length of the fireplace is 16 feet.

[mjpliv]

Brings to mind the steaks you used to see on the Flintstones cartoons! :shock:

Yabba Dabba Dooo!

[mjpliv]

By the by, bricks or stones, the water absorbtion rate still applies.