ASTM F1869 Calcium Chloride Moisture Vapor Emission Testing
What F1869 measures
ASTM F1869 measures moisture vapor emission rate (MVER) from the near-surface concrete, reported in lb/1000 ft²/24 h. It uses a sealed dome containing a pre-weighed calcium chloride dish. The dish absorbs vapor for 60–72 hours; the mass gain is converted to MVER.
Core rules
- Condition the test area near 75 ±10°F and 50 ±10% RH for 24 hours before and during the test.
- Clean the concrete surface; seal the dome; do not disturb the dish.
- Test frequency is the same pattern as F2170: three tests for the first 1,000 ft², one per additional 1,000 ft² or fraction.
- Results are emission rates, not relative humidity. Do not convert one directly to the other.
Worked example
A 100 mm dish gains 2.0 g over 72 hours. Dish area is about 0.00785 m² (0.0845 ft²). Mass gain per area = 0.00441 lb / 0.0845 ft² = 0.0522 lb/ft². For 1,000 ft²: 52.2 lb per 72 h. Per 24 h: 52.2 × 24/72 = 17.4 lb/1000 ft²/24 h. The arithmetic shows why units and test duration must be reported.
Traps
Using a dirty or damp surface, failing to seal the dome, shortening the exposure, or reporting grams instead of MVER all cost marks. F1869 is also sensitive to site conditions and does not measure deep-slab RH.