• Concrete

• Mortar

Concrete

Used to form solid foundations and footings, the strength of concrete is dictated by the ratio (by volume) of sand and stones (ballast) to cement powder. For most pond construction work a ratio of 4 parts ballast to 1 part cement is ideal, but if large areas are to be concreted, it is worth considering reinforcing the concrete with steel mesh. Most cement manufacturers will be happy to advise you.

The amount of water used in a concrete mix affetcs its handling properties: the more water used, the sloppier the concrete. Too much water will affect the strength of the cured concrete. For most practical pond work the concrete should stand rather like stiff mashed potatoes, and it should be used quicklyafter it has been mixed, before it stiffens up. There is a range of proprietary, but these are expensive and can affect the strength, and we would suggest avoiding them unless unusual circumstances prevail.

Concrete should not be mixed or used when frost or below-freezing temperatures are expected, as they make concrete crumble and become useless. If there is a possibility of frost once you've laid the concrete, protect it with sacking or insulating material which stop it from freezing. Equally, if high temperatures are anticipated, protect concrete from drying out too quickly, using plastic sheeting, damp hessain cloths or sacking

Mortar

This is the sand-and-cement mixture that is used to bond bricks and blocks together. It can be made in a variety of types and strengths: for buildng brick walls a mixture of 3 parts builder's sand to 1 part cement is standard. This can be coloured if required, using readily available  colorants.

CAUTION

The cement powder used to make concrete and mortar is corrosive. Always wear a dust-mask, gloves and goggles. If you get cement on your skin wash it off immediately with plenty of water.