Mounting bookshelves?

[182much]

I'm working on some shelves for our local Scout house.
The shelves will be 4ft X 8ft with the 8 ft being horizontal made out of 3/4 plywood.These will be mounted about 8 ft high
My original plan was to use the "french cleat" mounted to the concrete block wall with some 1/4" readheads.
I found out the wall is NOT grouted, so my plan now is to use some toggle type bolts along with some type of addhesive.
Any one have any other ideas?
This room is shared by pre-schoolers during the day and is located in earthquake country so saftey is a definite issue.

[cabinetman]

Could you be more specific as to how you mean 4'x8' "shelves".
.

[LCHIEN]

you mean 4'x8' plywood flat against the wall with shelves projecting outwards?
with sides? or with shelves and brackets mounted to the plywood?

Not clear. For a french cleat the height must be relatively long. Also the load can't bee too great. Around kids and in earthquake country, I'd be against it.

[182much]

Sorry for the confusion

Guess I should have more sleep before I post.
The shelves will be 16 inches deep by 4 ft high by 8 ft long mounted with the bottom 4 ft off the floor. There will be 1/4" plywood on the back of the carcass for stability.
The cleat on the case will be full length and will be recessed 1/2", the cleat on the wall will be 6" shorter than the case.
This shelf is to dispay trophies and pictures, so there shouldnt be to much weight involved

[chopnhack]

If you are using a 1/2" thickness material as a french cleat you should have ample load capacity for your intentions. I would think tapcons should be sufficient despite the cells not being grouted, just have to put enough to make sure you get several located in the "solid" portion of the block. You might want to beef up the back ply to 3/8" or 1/2" ply since you will be carrying a lot of weight with the back transfering thru the cleat. To clarify - the tapcons will not only go through the cleat, but for safety thru the back ply as well.
Hope this helps.