Product Description:

Our 20mm Ballast is a pre-blended mix of sharp sand and gravel supplied in a 25kg bag, ready to be combined with cement to make concrete. It is used for foundations and footings, shed and garage bases, fence post setting, concrete slabs and paths, bedding kerbs and edgings, and general concreting work on domestic and small commercial jobs.

Ballast takes the guesswork out of mixing concrete. Rather than buying sharp sand and aggregate separately and proportioning them on site, the two come ready blended in the correct ratio, so only cement and water need adding. The mix of particle sizes is what gives concrete its strength: the gravel provides the bulk and the load-bearing structure, while the sand fills the spaces between the stones so the cured concrete is dense and solid rather than honeycombed with voids.

For most general concreting, a common mix is one part cement to five or six parts ballast, with a stronger one-to-four mix used for structural work and foundations. Add clean water gradually and mix to a workable consistency — too much water weakens the finished concrete considerably, so it is better to add it sparingly. Place and compact the concrete before it begins to set, and protect it from frost and from drying out too quickly in hot weather while it cures. The 25kg bag suits small pours, repairs, and post setting, where a bulk bag would be more than is needed.