A bulk bag of 20mm ballast for mixing with cement to make a finer concrete. This ballast concrete aggregate bulk bag has excellent drainage properties, making it ideal to provide an even sub-base for paving slabs, block paving driveways, artificial grass and shed bases - it can also be used for securing fence posts. 20mm ballast, also known as "all-in" ballast, is a even mixture of sharp sand and 20mm crushed stone ballast. Ballast is not recommended for decorative use. This bulk bag of ballast is sourced from regional quarries to match local requirements, so the colour of the concrete ballast along with the price of a jumbo bulk bag will vary region to region.