ASTM C33/C33M
Standard Specification for Concrete Aggregates
The sand and stone that make up most of the volume of concrete: how the particle sizes must be distributed and what contaminants are not allowed.
Who needs it
Aggregate producers, batch plants, mix designers, and specifiers dealing with durability or alkali-reactivity concerns.
What the test involves
It defines grading requirements for fine and coarse aggregate using standard size numbers, so that a specified stone size means the same thing everywhere. It also limits deleterious substances such as clay lumps, friable particles, organic impurities, and materials that break down under weathering. Additional provisions address soundness and, where relevant, potential reactivity with cement alkalis.
Common misconceptions
- Aggregate is not inert filler that can be swapped freely. Its grading directly controls water demand, workability, pumpability, and finishing behavior.
- 'Washed' does not automatically mean compliant. Grading and deleterious limits are separate concerns from being visibly clean.
- Locally available aggregate is not always compliant aggregate, and in some regions the only economical stone is potentially reactive, which is what alkali-reactivity mitigation is for.
Official source
We summarize scope and purpose only. The full text belongs to the issuing body — read it at the official source. ASTM International