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).