20mm blue metal aggregate is a slightly larger version of the 10mm variety. It is used in applications that require better drainage, such as retaining walls, drainage trenches, and larger concrete slabs. The 20mm size is excellent for projects requiring robust structural support, as the larger stones provide superior load-bearing capacity. Like its smaller counterpart, this aggregate is produced from crushed basalt rock and retains the same strength and durability. It’s often used in combination with finer aggregates or sand to create a stable foundation in construction and landscaping projects.