# ASTM F2170

Source: https://coatmentor.com/standards/astm-f2170/ · Updated 2026-10-14

Relative humidity inside a concrete slab, measured with in-situ probes.

**Publisher**: ASTM International

**Area**: Concrete

ASTM F2170 measures the relative humidity inside a concrete slab. A probe in a lined hole drilled into the slab reads the humidity at a set depth, which tells how wet the concrete still is under the surface.

## The procedure

- Keep the slab and the space above it at service conditions for at least 48 hours first.
- Drill to 40 % of the slab depth for a slab that dries from the top only, or 20 % for one that dries from both sides.
- Fit the liner, cap it and let the hole reach equilibrium for 24 hours before the reading. Older editions asked for 72 hours.
- Test at three places for the first 1,000 ft² (100 m²) and one more for each further 1,000 ft², including near exterior walls.

Like F1869, F2170 has no pass mark of its own. The coating or flooring maker sets the limit.

**2** practice items in the members area mention ASTM F2170 (CIP 2: 1 · FROSIO written: 1).

## Related

- **Concepts:** [Drying, curing and recoat windows](https://coatmentor.com/learn/cure-and-recoat/)
- **Standards:** [ASTM F1869](https://coatmentor.com/standards/astm-f1869/) · [ASTM D4263](https://coatmentor.com/standards/astm-d4263/)

## About this page

This page describes the subject of ASTM F2170 in our own words; it does not reproduce the standard. For the full text, buy the current edition from ASTM International. Checked on 2026-10-14; errors go in the [corrections log](https://coatmentor.com/method/). CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.