# Fineness Modulus

For aggregates used in PCC, another common gradation description for fine aggregate is the fineness modulus. It is described in ASTM C 125 and is a single number used to describe a gradation curve. It is defined as:

- Canonical URL: https://pavementinteractive.org/reference-desk/testing/aggregate-tests/fineness-modulus/
- Last updated: 2018-09-05
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- Standards: ASTM C125

For aggregates used in PCC, another common [gradation](https://pavementinteractive.org/glossary/gradation/) description for fine aggregate is the fineness modulus. It is described in ASTM C 125 and is a single number used to describe a gradation curve. It is defined as:

$$\mathit{F.M.} = \frac{\sum \left( \text{cumulative percentage retained on specified sieves} \right)}{100}$$

where:

- $$\mathit{F.M.}$$ = fineness modulus
- $$\text{specified sieves}$$ = 0.150 mm (No. 100), 0.30 mm (No. 50), 0.60 mm (No. 30), 1.18 mm (No. 16), 2.36 mm (No. 8), 4.75 mm (No. 4), 9.5 mm (0.375-in.), 19.0 mm (0.75-in.), 37.5 mm (1.5-in.), and larger increasing in the size ratio of 2:1.

The larger the fineness modulus, the more coarse the aggregate. A typical fineness modulus for fine aggregate used in PCC is between 2.70 and 3.00.

## Standard Test Methods

- ASTM C 125: Standard Terminology Relating to Concrete and Concrete Aggregates