Lime comes in various categories and types. Not all are commonly used in the DIY environment.
The lime used by ‘amateurs’ is the lime called (in France) ‘chaux aerienne eteinte pour le batiment’ (CAEB). It is prepared from very pure limestone, and is an extremely fine powder. It is sometimes also known as ‘fleur de chaux’.
‘Chaux hydraulique naturelle’ is also sometimes used, but is less pure and has a slight grey tint.
Stand well back after emptying lime into a cement mixer. It tends to come back out in a fine cloud, coating you head to foot ‘Laurel and Hardy’ style, and making you choke at the same time.
Visit the walls page for a list of the diferences between cement and lime when used for pointing and stonework. Suffice to say here, lime has numerous advantages during the renovation of an old building, and few disadvantages. The only general disadvantage of lime is that its ultimate strength is less than that of cement, so would not usually be used for bricklaying, for example, and likewise would not be used in lintels or in other work with a ‘structural’ factor.
It can (and should) be used in place of cement for rendering walls and pointing walls, although a small amount of white cement can be added to give extra strength.