Concrete

[Guest]

I'm trying to repair / maintain a quay originally built by Trinity House to supply a nearby light house, problem is that it's at the bottom of a 100ft cliff, accessed by rock cut steps, to save me a lot of effort does anyone know if I can use beach sand and seawater (and cement obviously) to make concrete? I realise this isn't strictly related to a boats but any help would be appreciated.

 

[Mirelle]

Iam not the right person to ask, but I am pretty sure that the answer is "no", you would need to wash the sand and use fresh water. I hope an expert can answer your question properly, but I have never heard of unwashed sea sand and salt water being used.

 

[spark]

Using beach aggregate (natural mix of sand and gravel with bits of shell in it) used to be standard practice hereabouts until the "conservationists" got their underwear in a fankle. I did a shed founds and floor with it which cured so hard when I came to demolish 10 years later I had serious difficulties. However, the usual source was on the beach at the mouth of a small river so it could have been less salty than normal. Also it rains a lot here which may also have washed some of the salt out before it got used. We always used fresh water for the mix and I suspect that salt will not work.

 

[Guest]

Hi Warren,

It is not advised, but done almost everywhere in the world! Most sands contain salts anyway (hence efflorescence on newly built buildings -plaster and brick) but due to the high calcium content from shells, the concrete is (supposedly) weakened. If you are including reinforcing steel, think twice, as the salts will affect the corrosion of the steel, meaning that you might be doing the same exercise again sooner than you'd expect. (You can buy s/s reinforcing now, but at a price!). Beach sand can thus pass, but seek an alternative water supply. Good luck
Carl

 

[Guest]

Thanks for the information / opinions. Beach sand and fresh water it is then!!