What should be used to fill large voids within a small 2'widex3'tall brick wall?
I have this little "retaining" wall which is 2 bricks (lengthwise) wide and the mortor joint between them (on the top of the wall) has crumbled. When I got some of this crumbly mortar removed, I found sloppy construction, i.e. huge voids within the walls interior. I want to fill it in with something, with whatever can be recommended keeping in mind freeze/thaw cycles. We're not talking about a serious load bearing retaining wall here...It's only about 3 foot tall and is more for looks than anything else. I really just need a recommendation of the best filler material...I've considered plain washed gravel, sand, expansion foam and even the mortar itself...the same batch I plan to use for repairing the joint. However this might be unnecessary and more costly than this job needs to be. Any suggestions would be greatly appreciated...winter will be here very soon!!! Thanks in advance.