SAMPLE OF THE WEEK // The humble fibre cement sheeting sample. It’s a common sample type that we see in the lab daily. Fibre cement sheeting is considered a bonded material with an asbestos concentration ranging from 15% to 50%. This material was made up of cement and/or a portland cement (usually limestone mixed with a second material containing clay as a source of alumino-silicate). The resulting material is strong, resilient to degradation (the elements, knocks and bumps) and chemical weathering. Some asbestos cement sheeting (or ACM, fibro or cladding as it’s known in the industry) was made up purely from chrysotile. Chrysotile is hydrophilic meaning that it attracts water and moisture, whereas the amphiboles such as amosite and crocidolite are considered hydrophobic. The advantage of hydrophobic material in an exterior wall and roof material (such as cladding, sheeting and super-six roofing), is that it constantly repeals water away from the material matrix (particularly the cement component). This may decrease the rate of weathering from wind, rain and sun. Even though asbestos sheeting is considered bonded in nature, highly dilapidated material can give off high fibre release in some situations.