Asbestos cement - water absorption test
A water absorption test should be carried out on a suitable sample (ie a minimum of 3 cm x 3 cm or 9 cm2) which is free of any adhering material (partially painted samples can be used but may need longer to absorb water). All asbestos materials should be handled inside a suitable extraction or recirculating air cabinet fitted with high-efficiency filters, or sealed in a suitable container. The following steps should be followed:
- Remove the sample of asbestos from packaging/container and either dry for a minimum of 12 hours at 50-110 °C or until the difference between two consecutive weights made at an interval of not less than 1 hour, is less than 1% of the mean of the two measurements.
- Before weighing, allow time for the sample to cool and condition.
- If weighing outside the containment cabinet, place the sample in a suitable pre-weighed sealable container (eg a sealable plastic bag) and weigh to the nearest 0.01 g. Calculate the dry weight of the sample by subtracting the weight of the container.
- After weighing, remove the sample from any container and completely immerse in water for a minimum of 15 minutes and until no more visible signs of bubbles being formed are observed.
- If the sample is seen to start to disintegrate during immersion, the test should be terminated and the sample reported as a licensed asbestos material.
- If intact, remove the sample from the water and place it on paper towel for 1 minute per side (upper and lower surfaces) to remove any excess surface water.
- Place the sample in the pre-weighed sealable container and reweigh. Calculate the wet weight of the sample by subtracting the weight of the container.
- Calculate the percentage of water absorbed by the sample using the following equation: ((wet weight - dry weight)/dry weight) x 100.
- If the percentage of water absorbed is <30% report as an asbestos material for which a licence is not required to work on (eg asbestos cement). If >30% report as an asbestos material for which a licence is required to work on (eg asbestos insulating board (AIB) or millboard).
- Asbestos essentials
- Asbestos: The licensed contractors' guide
- Managing and working with asbestos: Control of Asbestos Regulations 2012