Delaterious Materials Flashcards
Name five deleterious materials
- Asbestos and Asbestos Containing Materials
- Woodwool
- Lead and lead paints
- High Alumia Cement
- Silica dust
Define what is meant by deleterious materials?
Deleterious materials are materials that are harmful, either harmful to health or that cause failure within buildings. All materials could be deleterious in the wrong circumstance
What is nickel sulphide reaction?
Nickel sulphide reaction is a spontaneous fracture of toughened glass as a result of impurities in the molten glass. The fracture is caused by nickel expansion. It can be combated by heat soak testing the glass prior to installations
What is urea formaldehyde foam?
Urea formaldehyde foam is a foam product that was used for cavity wall insulation in the 70s and 80s. There is evidence that it can be carcinogenic, it is banned as a toxic substance
What is the risk associated with lead in construction, and where would you expect to find it?
Lead can be poisonous if ingested. It was used for pipework and solder joints, and would contaminate water. It was also used in paint, and care should be taken as it can be inhaled when rubbing down. Paint can be tested for lead content
What is calcium silicate brickwork?
Calcium silicate brick are made from a combination of lime, sand and crushed flint. Due to their make up they have a tendency to shrink after construction and are susceptible to movement when wetting (often diagonal cracking). Sufficient movements joints - every 7-9 meters are required for construction with calcium silicate brickwork
What is sick building syndrome?
Sick building syndrome is a condition where building occupants experience symptoms similar to that of a cold - headache, lethargy, scratchy throat - while in a building, but that disappear after leaving. Cause is unconfirmed, but it thought to be linked to light level, air conditioning, fresh air etc.
What is a woodwool slab, and when would its use be considered dangerous?
Woodwool slabs are bonded softwood shavings are cement, compressed to create boards. They are commonly used as permanent formwork, and also as insulation.
When used as formwork, the materials can create void within the concrete, creating honeycombing to concrete, therefore reducing the fire and structural properties
What is high alumia cement?
HAC is an concrete additive that was used in the 50s and 60s, and was banned in the 1970s. It caused concrete that hardened faster, however it was found that over time is looses strength, particularly in wet environments. Can be suspected in pre-cast concrete members from the right time
What is silica dust?
Silica dust is produced when working with a number of materials, including stone and clay when cutting. It can be dangerous to health if inhaled, and therefore measures should be taken to prevent dust (wetting/breathing apparatus)
