Fixing and buying guide

What is 20mm ballast and who needs it

20mm ballast is a pre-blended aggregate containing both sand and gravel in proportions suitable for concrete mixing. It is used by builders, groundworkers, and serious DIY enthusiasts for creating concrete for foundations, paths, bases, and general structural work. The 20mm stone size makes it versatile for most standard concrete applications where you need a durable, load-bearing finish.

Choosing the right quantity

Each bag weighs 25kg and contains the combined sand and gravel needed for concrete production. Calculate your project volume in cubic metres, then determine how many bags you will need. For reference, approximately 40 bags of 25kg ballast are required per cubic metre of concrete, though this varies depending on your exact mix design and water content.

• Small repairs or patching: 1-5 bags
• Garden path or small base: 10-20 bags
• Larger structural work: order in bulk or by the tonne

Preparing to use your ballast

Before mixing, inspect the ballast for any debris or contamination. Store bags in a dry location to prevent moisture absorption, which can affect concrete strength and workability. When you are ready to mix, combine the ballast with cement and water according to your concrete specification. The pre-blended nature of this product means you do not need to source gravel and sand separately, saving time on site.

Pack contents and storage

Each purchase is a single 25kg bag of 20mm ballast. The material is supplied loose within the bag. Keep bags stacked on a level surface away from standing water, and protect from prolonged rain if storing outdoors for extended periods.

• Weight per bag: 25kg
• Aggregate size: 20mm
• Composition: sand and gravel blend ready for concrete