I think I used cement that had partially hydrated 50%. So, in effect, I
might have a made a mix that was 6 to 1 or perhaps worse than that. It
certainly was not good enough. When I mixed it I did not know about
hydration. So, that's why the cement was so sandy and weak.

What's happening is that I have a small room that's 118 Cm wide. I'm
putting up shelves 118 Cm wide by x 61 Cm deep. The distance
between each shelf is 42 Cm. Each shelf will rest on two pieces of
wood one bolted onto the left hand wall and one on the right hand
wall. I'm using M6 x 115mm bolts anchor bolts to bolt the wood
to the walls.

The right hand wall is a concrete wall. The left hand wall I believe is
breese block.

If I chuck out my old cement and get new, I think a 3 sand to 1 cement
mix should be good enough, unless anyone says different.

Now the shelves will have books on and a shelf will be be completely
filled from top to bottom. So, we have a situation where a shelve
has to hold up a volume of books that is 42 Cm high x 118 Cm
wide and 61 Cm deep. Not sure of the weight but that would
amount to quite a heavy weight on a shelf.

Should I chisel out holes in the breese block and fill these holes with
mortar. Then drill that out to hold the anchor bolts? TIA.