Use of Aggregates Containg Sulphides for Unreinforced Roller Compacted 1

[wollundry5]

We are rehabilitating a dam by using unreinforced Roller Compacted Concrete. The problem is that the dam is located
in a very remote area and lacks commerically available aggregate and would be cost prohibitive to bring this material to site.There are local sources of rockfill (rhyolite and granite), however, they contain a limit amount of sulphide mineralisation. Does anybody have any advice on using this as a source of unreinforced concrete aggregate?

 

[dbuzz]

Soluble salts, particularly chloride and sulphate salts, are commonly found in materials used in concrete. Substantial levels of soluble salts in aggregate can cause efflorescence (deposition of salts on the exposed surface), corrosion of reinforcing steel or disintegration of concrete. Consequently, limiting of the salt presence is important to concrete durability.

Your country’s design code for concrete should specify limits for chlorides and sulphates.

In Australian practice, aggregates containing sulphides or sulphate salts in proportions which result in sulphate content of the concrete exceeding 5% (by mass of Portland cement) are not to be used.

 

[unclesyd]

Not much help with numbers.
I don't know what the limits on the sulphide/sulphate content was, but for years in my area (Birmingham, Al US) Blast Furnace Slag was the aggregate of choice for concrete and all other aggregate use. Like I said I don't have the numbers but both sulphide and sulphate were fairly high in the aggregate.