Standard Specification for Concrete Ballast Block

Scope

ASTM C1884-18 is the Standard Specification for Concrete Ballast Block. It covers dry-cast concrete ballast blocks that are primarily used to ballast rooftop equipment. The units are machine-made from hydraulic cement, water, and suitable mineral aggregates, with or without the inclusion of other materials. A concrete ballast block is defined as a manufactured concrete unit used primarily to provide weight for stabilizing rooftop equipment, with an explicitly cited example application being ballast for photovoltaic arrays.

Key Requirements Relevant to PV Ballast

• Physical requirements (density, water absorption, and minimum net-area compressive strength) must be met at the time of delivery to the purchaser.
• Minimum net-area compressive strength is the same across all density classifications: an average of three units must meet a stated minimum, with a lower allowable threshold for any individual unit.
• Freeze-thaw durability must be demonstrated, by test or proven field performance, in areas subject to repeated freezing and thawing under saturated conditions; when tested, weight loss is evaluated over 100 cycles.
• Units must be sound and free of cracks or defects that would impair placement, strength, or permanence (minor incidental cracks/chipping are not grounds for rejection).
• Permissible dimensional and weight variations are specified, and a shipment is limited in the percentage of non-conforming or broken units it may contain.
• Sampling and testing reference ASTM C140/C140M (compressive strength, absorption, density, weight, dimensional tolerances) and ASTM C1262/C1262M (freeze-thaw durability).