Huge wrote:
On 2009-07-22, Andy Champ wrote:
Broadback wrote:
When I was installing a mooring point for a boat, which was half and oil
drum buried then filled with concrete I ask the owner of the next door
boat if it was ok to use that sand from the shore. His reply was it was
fine for that job, but would not be good for, say, a bridge, and
concrete/cement made from sea sand was nothing like as strong.

I suspect that's not the sea _sand_ so much as the contamination with
sea _water_ that's the problem. I think it messes up the reactions.

But can I find a reference to back that up? Can I heck.

When we visited Eilean Donan castle, we were told that it was falling down
because the 1919/32 restoration used concrete made with beach sand. I have no
idea if this is true - perhaps they just wanted our money.


beach sand is rather smooth..and with weak cement wont hold up so well.
builders sand is a bit sharper. With proper portland cement though,
there's bugger all difference, and I cant see salt weakening the mix much.

The tumbling castle sounds to me far more like a builder who simply
skimped on cement. They all do.