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1. Building Pathology > 07 Deleterious Materials > Flashcards

07 Deleterious Materials Flashcards

1
Q

What is a deleterious material?

A

Deleterious materials are those that are either dangerous to health, commonly cause failures in buildings or are environmentally damaging

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2
Q

Name 10 deleterious materials.

A
  1. Asbestos
  2. HAC Concrete
  3. Calcium Silicate Bricks
  4. Lead
  5. Woodwool Slabs
  6. Hollow Clay Pot Floors
  7. Brick Slips
  8. Clinker Concrete
  9. Chlorofluorocarbons
  10. Machine Made Mineral Fibre
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3
Q

What deleterious materials might you find in a 1960s office block?

A
  1. Asbestos
  2. HAC Concrete
  3. Woodwool slabs
  4. Brick slips
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4
Q

What is asbestos?

A
  • Asbestos is the generic term for several mineral silicates occurring naturally in fibrous form
  • It was extensively used as a building material in the UK from the 1950s through to the mid-1980s
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5
Q

What guidance is available in relation to asbestos?

A
  1. RICS GN ‘Asbestos and its implications for surveyors and their clients’ (3rd ed. 2011)
  2. HSE website
  3. HSE Approved Code of Practice - Managing and Working with Asbestos
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6
Q

Why is asbestos dangerous?

A

When asbestos fibres are inhaled, they can cause serious diseases, which often take a long time to develop but once diagnosed it is usually too late to do anything:

  1. Asbestosis - permanent scaring of lung tissue (fibrosis), causes lungs to shrink, stiffen and lose elasticity
  2. Lung cancer
  3. Mesothelioma - cancer of the lining of the lung or, in rare cases, the abdominal cavity (crocidolite only)
  4. Pleural thickening - lining of the lung (pleura) thickens and swells, causing shortness of breath and discomfort in the chest
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7
Q

What are the different types of asbestos?

A
  1. Chrysotile (white) - accounts for 90% used commercially
  2. Crocidolite (blue) - accounts for 6% used commercially
  3. Amosite (brown) - accounts for 3% used commercially
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8
Q

Which is considered the worst type of asbestos?

A

Crocidolite (blue)

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9
Q

When was asbestos banned?

A
  1. 1970 - voluntary ban of crocidolite
  2. 1985 - crocidolite and amosite banned by law
  3. 1999 - chrysotile banned
  4. 2000 - everything else and most second-hand supply (except for very high performance materials) banned
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10
Q

Where might you find asbestos in buildings?

A
  1. Sprayed coatings (e.g. ceilings, walls, beams, columns)
  2. Asbestos cement water tank
  3. Loose fill insulation
  4. Lagging on boilers and pipes
  5. AIB (Asbestos Insulating Board) ceiling tiles, partition walls, panels in fire doors, around boilers, behind fuse board, bath panel, behind fire, interior/exterior window panels
  6. Toilet seat and cistern
  7. Rope seals, gaskets and paper
  8. Vinyl floor tiles
  9. Textiles (e.g. fire blankets)
  10. Textured decorating coatings (e.g. artex)
  11. Asbestos cement panels (e.g. roof covering, wall cladding)
  12. Asbestos cement gutters, downpipes, soffits, flues
  13. Roofing felt
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11
Q

Where might you find white asbestos?

A
  1. Cement tiles
  2. Floor tiles
  3. Gaskets
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12
Q

Where might you find blue asbestos?

A
  1. Sprayed coatings (limpet)
  2. Insulation
  3. Old textiles
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13
Q

Where might you find brown asbestos?

A
  1. Wall panels
  2. Ceiling tiles
  3. Pipe insulation
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14
Q

What legislative controls govern asbestos?

A
  • Health and Safety at Work etc. Act 1974:
    • Enabling act for asbestos legislation
    • Failure to comply is a criminal offence
  • Control of Asbestos Regulations (CAR) 2012
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15
Q

What are the requirements of the current asbestos regulations?

A

Places a duty on the owner or person/organisation that has responsibility for the maintenance or repair of non-domestic premises (i.e. those in control of the premises):

  1. If existing ACMs are in a good condition and not likely to be damaged, they may remain in place, their condition monitored and managed to ensure they are not disturbed
  2. Duty holders have a ‘duty to manage’ asbestos and protect anyone within the building from the risks of exposure
  3. If any building or maintenance works are to be done, duty holders must ensure asbestos is identified, its condition and risks assessed and manage and control these risks
  4. Certain work with asbestos is to be carried out by licensed contractors
  5. Certain work with asbestos can be carried out by non-licensed contractors, but must still have effective controls
  6. The control limit is 0.1 fibres per cubic centimeter (averaged over 4 hours)
  7. Training is mandatory for anyone liable to be exposed to asbestos fibres at work
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16
Q

What changes have been made to the asbestos regulations in 2012?

A
  1. Some non-licensed work needs to be notified to the relevant enforcing authority
  2. By April 2015, ensure notifiable non-licensed workers have a medical examination at least once every 3 years
  3. Keep a record of notifiable non-licensed work, e.g. the type and duration of work done with asbestos along with copies of all medical records, for 40 years
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17
Q

What is the significance of the asbestos control limit?

A
  • This is the trigger for which regulation 18(2) ‘Designated Areas’ applies, where ‘respirator zones’ must be established, to which access is restricted to ‘competent’ persons and suitable respirators must be worn at all times
  • If the control limit is not likely to be exceeded, then it is one of a number of circumstances set out in regulation 3(2) for which specific regulatory requirements may not necessarily apply
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18
Q

Explain to your client what his responsibilities are as a duty holder of premises with regards to asbestos under the current regulations?

A

Duty to manage:

  1. Take reasonable steps to determine the location of likely ACMs
  2. Presume materials contain asbestos unless strong evidence otherwise
  3. Make ACM location and condition record and keep up-to-date
  4. Risk assess the likelihood of anyone being exposed to fibres
  5. Prepare a plan setting out how risks are to be managed
  6. Take necessary steps to put the plan into action
  7. Review and monitor the plan periodically
  8. Provide awareness training to anyone working on ACMs
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19
Q

Name the types of asbestos survey and when they are required.

A

Management Survey:

  1. Required to manage ACMs during the normal occupation and use of premises
  2. Locates ACMs that could be disturbed by normal activities, maintenance or installing new equipment
  3. Involves minor intrusions to make a Materials Assessment, which shows the ability of the ACM to release fibres if disturbed
  4. Guides the client in prioritising any remedial work

Refurbishment / Demolition Survey

  1. Required where the premises, or part of it, is being refurbished or demolished
  2. Locates all ACMs before works begin
  3. Does not need to record ACM condition
  4. Involves destructive inspection (areas surveyed must be vacated and ‘fit for reoccupation’ after survey)
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20
Q

Does asbestos have to be removed from a building and why?

A

Asbestos should not be removed unnecessarily as doing so could be more dangerous than leaving it in place and managing it

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21
Q

What remedial works can be undertaken where materials cannot be removed in their entirety?

A

Asbestos can be encapsulated, e.g. work to enclose or seal ACMs in good condition

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22
Q

What are the statutory requirements for the removal of materials containing asbestos?

A
  1. If existing ACMs are in a good condition and not likely to be damaged, they may remain in place, their condition monitored and managed to ensure they are not disturbed
  2. If ACMs are likely to be disturbed, then depending on the type, condition and extent of works being carried out to the ACM will depend on the category of work required
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23
Q

What are the different asbestos works categories?

A
  1. Licensed
  2. Non-licensed
  3. Notifiable non-licensed
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24
Q

If you needed to remove asbestos, how would you determine which works category the work would fall under?

A

The HSE has produced a decision flowchart and illustrative diagram to help determine which category the work falls under

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25
Q

What are the general requirements for licensed asbestos removal works?

A
  1. Requires a licensed contractor to undertake the works
  2. Higher-risk work
  3. All licensable work must be notified to the appropriate enforcing authority at least 14 days before works start
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26
Q

What are the general requirements for non-licensed asbestos removal works?

A
  1. Must meet certain requirements within CAR 2012 to be exempt from being licensable
  2. Generally involves work that is sporadic and of low intensity
  3. Does not require a licensed contractor to undertake the works but work must still be:
  • Risk assessed
  • Carried out with appropriate controls in place (provided for by the various HSE equipment and method sheets)
  • Undertaken by those carrying the correct level of information, instruction and training
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27
Q

What are the general requirements for notifiable non-licensed asbestos removal works?

A

Requires employers to:

  1. Notify the relevant enforcing authority of the works
  2. Designate areas where the work is being done (marked with suitable warning notices, restricted to those carrying out the work, no food or drink within designated areas)
  3. Ensure medical examinations are carried out at least every 3 years whilst continuing to undertake such work
  4. Maintain registers of work (health records), including nature and duration of works and dates of medical examinations (must be kept for at least 40 years)
  5. Still requires a risk assessment, appropriate controls and the correct level of information, instruction and training as per non-licensed work
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28
Q

Give an example of work that may be included under each asbestos work category.

A
  1. Licensed - removing sprayed coatings, disturbance of pipe lagging or work on asbestos insulation board (AIB) where the risk assessment indicates it will not be of short duration
  2. Non-licensed - work involving asbestos cement products (e.g. roof sheeting, tiles and rainwater goods), short duration work to AIB or encapsulation of ACMs in good condition
  3. Notifiable non-licensed - asbestos cement products that have been/will be substantially broken up
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29
Q

Define what asbestos works of a ‘short duration’ means.

A

Defined as no more than 2 hours in any 7 day period and no one person works for more than one hour in that 2 hour period

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30
Q

Do licensed contractors still need to notify asbestos works classed as notifiable non-licensed work?

A

Yes

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31
Q

Is the asbestos content of AIB and asbestos cement sheet similar?

A

No, AIB is considered to be a higher risk material than asbestos cement sheet

32
Q

If asbestos is identified during a refurbishment project, what actions would you take as Contract Administrator?

A
  1. Stop work immediately
  2. Isolate anyone significantly exposed
  3. All put on RPE (Respiratory Protective Equipment)
  4. Keep everyone out of the area
  5. Put up warning signs
  6. Engage with an approved contractor to clear the area and decontaminate anyone exposed
  7. Wipe down any dust on clothes with damp rags
  8. Dispose of rags and contaminated clothes as asbestos waste
  9. Keep a record of the event
33
Q

What is HAC concrete?

A

High Alumina Cement Concrete:

  1. UK manufacture began in 1925 to provide concrete that would resist chemical attack, particularly in marine applications
  2. The cement developed high early strength, although its relatively high cost prevented extensive use
34
Q

Where would you find HAC concrete?

A

During the late 1950s and 1960s, the main use of HAC was for the manufacture of precast, prestressed components (‘X’ and ‘I’ beams for floor or roof decks) that could be manufactured quickly to offset the high cost

35
Q

Why is HAC concrete problematic?

A
  1. HAC undergoes a mineralogical change known as conversion, where the concrete increases in porosity, thus resulting in a loss of strength and a reduction in resistance to chemical attack
  2. The higher the temperature during the casting of the concrete, the quicker conversion takes place
  3. Highly converted HAC concrete is vulnerable to acid, alkaline and sulphate attack, which requires water as well as the chemicals to be present persistently over a long period of time at normal temperatures
  4. Like ordinary concrete products, HAC is also affected by carbonation
36
Q

What type of environment does HAC concrete not like particularly?

A

In a warm and moist environment, a serious reaction known as alkaline hydrolosis may occur (resulting in a severe loss of strength and integrity), where high alkali levels may be present from the use of certain types of aggregate or where alkalis may have ingressed from plasters, screeds or woodwool slabs

37
Q

When was HAC concrete banned in the UK?

A

Banned from structural use in 1976 following the collapse of a swimming pool roof and several school roofs in the early 1970s, although new uses are now becoming established under the name Calcium Aluminate Cement (CAC)

38
Q

Why may it be contentious to label HAC concrete as a deleterious material?

A
  • On no occasion has weakening of the concrete due to conversion been the sole cause of failure - in the case of the original historic failures, manufacturing faults were eventually discovered (e.g. high water content during mixing and high temperatures during curing)
  • There has been no recorded instances of a failure of a floor in this country
39
Q

How would you identify HAC concrete?

A
  • Visual inspection:
    • Chemical attack is usually very localised and the concrete typically degenerates to a chocolate brown colour and becomes very friable, often due to sulphate attack
    • Alkaline hydrolosis is characterised by white powdery deposits and a severe loss of strength and integrity
  • Rapid chemical testing - usually sufficient to distinguish HAC from other elements, but can give misleading results if not used with care (e.g. carbonated concrete or a sample with gypsum plaster can give a false indication that HAC was used)
  • Laboratory analysis - used for conclusive testing
  • Examination of construction drawings - a full list of HAC component suppliers is found in the BRAC (Building Regulations Advisory Committee) guidance
40
Q

Your client’s building is known to have been built using HAC concrete. Is this a problem and what would you recommend he does about it?

A
  1. Carry out a strength and durability assessment in line with the Building Regulations Advisory Committee (BRAC) guidance (now published by the BRE)
  2. Removal - where necessary, the removal of the HAC elements altogether
  3. Replacement - removing or replacing part of the HAC element’s original load-bearing function by adding a secondary support may be satisfactory
  4. Carbon plate bonding - an increasingly common method that is likely to be far less disruptive than other, more conventional systems
41
Q

What are the advantages of using calcium silicate bricks?

A
  1. Resistant to frost attack
  2. Virtually free from soluble sulphates, making them resistant to sulphate attack
42
Q

What problems are associated with calcium silicate bricks?

A
  1. Shrinkage is the most commonly perceived fault
  2. Thermal movement is likely to be about 1.5 times that of clay brickwork
  3. Unlike clay, they usually undergo an initial irreversible shrinkage on laying (clay brickwork tends to expand), which can cause cracking
43
Q

Why may it be contentious to label calcium silicate bricks as a deleterious material?

A

Can perform satisfactorily provided the correct precautions are taken in the design of walls (e.g. incorporating sufficient movement joints)

44
Q

How can calcium silicate bricks be identified?

A
  1. Fine, natural cream colour
  2. Small particles of flint up to about 3mm are often visible
  3. Manufactured with coarser aggregates, so the edges of the bricks are less well defined
  4. Concrete bricks tend to have small pieces of stone aggregate visible and have a fairly coarse surface
  5. Not fired in the manner of clay bricks, so no tell-tale kiss marks, wire marks or fine splits in the surface
  6. On older bricks, scraping the surface of the brick will reveal that they are easily marked or cut, while concrete bricks can be a good deal harder
  7. Laboratory testing through the use of x-ray diffraction could also be used
45
Q

How can you tell when cracking to a wall has been caused by the improper use of calcium silicate bricks?

A
  1. Identify the bricks as calcium silicate bricks
  2. Lack of adequate movement joints
  3. Cracks of constant width (as opposed to tapering cracks)
  4. Shrinkage cracks so generally no displacement evident (brickwork sliding off a damp-proof course, cracking at corners or evident disruption)
46
Q

What steps would you recommend when specifying the installation of calcium silicate bricks?

A
  1. Vertical movement joints should be provided at intervals of between 7.5-9m (BS 5628-3), with the first joint from a return normally half that distance
  2. To minimise the effects of movement, the ratio of length to height of masonry panels should not exceed 3:1
  3. Below damp-proof course level, the moisture content of the brickwork will be fairly stable and so movement joints are not required
  4. Should not be wetted during laying - if suction is too great, additional water can be added to the mortar (within reason) or very light wetting undertaken
  5. Should not be used in solid walls with clay facings or backings because of the propensity of the bricks to shrink in contrast with the expansion of clay brickwork
47
Q

Why is lead considered a deleterious material?

A
  1. Lead is toxic and inhalation/ingestion can cause health problems, particularly in children and pregnant women
  2. Interferes with the development of the nervous system, causing potentially permanent learning and behaviours disorders
  3. Higher doses can lead to renal damage, severe colic, abdominal pain, headaches, confusion and seizures leading to death
  4. Uncertainty over whether or not lead poisoning can lead to cancer
48
Q

What is the HSE requirement under the Control of Lead at Work Regulation 2002 for lead used in construction?

A

???

49
Q

Why is lead banned from use as a construction material for some products, but not for others?

A

Mere handling of lead will not cause poisoning, so lead in roofing is not perceived to be dangerous

50
Q

Where may you find lead in buildings?

A
  1. Water pipes
  2. Paint
  3. Roofing (e.g. flashing)
51
Q

When was the use of lead water pipes banned in the UK?

A

Banned for this use in 1969

52
Q

When was the use of lead based paint banned in the UK?

A

Environmental Protection (Controls on Injurious Substances) Regulations 1992

  • Prohibits the retail sale of all lead paints to the public
  • Restricts use of lead paint to special circumstances (e.g. redecoration of listed historic buildings)
53
Q

What procedures should be undertaken when removing lead paint?

A
  1. Wear disposable overalls and a FFP3 mask
  2. Only strip back old paint if it is flaking, chipping or a risk to children
  3. If paint is in poor condition, remove using a combination of chemical paint stripper, wet abrasive paper and on-tool extraction
  4. If paint is in good condition use wet abrasive paper to make a key for the new coat of paint
  5. Remove any debris with a damp cloth
  6. Place any debris, cloths, abrasive paper in a plastic bag for disposal
  7. Wash hands and forearms before eating or drinking
54
Q

What are VOCs and why are they problematic?

A
  • VOCs are solvents that are commonly used in paint to keep it in liquid form, which get released into the atmosphere when the paint dries
  • VOCs can cause headaches, nausea and dizziness when released and some (particularly benzene) are known carcinogens
    • Water-based paints are now used as a substitute as a result
55
Q

What are the advantages of using paints and glues containing VOCs?

A

The advantage of using VOCs in paint is it evaporates quickly when applied to a surface, which leaves behind more pigment and therefore requires fewer applications

56
Q

What is woodwool slab?

A
  1. Made from long-fibre wood shavings compressed and bound together with cement
  2. Used mainly through the 1950s-1970s as roof decking or permanent shuttering for in-situ concrete
  3. Fire resistant, has good insulating properties and is more environmentally friendly than thermoplastics and resin-bonded material
57
Q

How can the use of woodwool slab become problematic?

A
  1. Only problematic when used as permanent shuttering to reinforced concrete
  2. Due to the compressive nature of woodwool slabs, compaction of the concrete may be inadequate as the woodwool slab absorbs some of the energy
  3. This lack of compaction can result in voids and honeycombing to the underside of the concrete, sometimes leaving no cover for the reinforcing steel
  4. This problem is exacerbated if the woodwool slabs are ribbed, as it makes compaction within the narrow ribs very difficult
  5. As the woodwool slabs remain in place, such defects can remain undetected
58
Q

What remedial work should be considered where woodwool slab has been identified?

A
  1. Discovery of woodwool slabs does not automatically mean a problem exists, as the concrete may been properly placed and compacted
  2. Physical opening up and assessing the concrete soffit is the most reliability means of problem detection
  3. Repairs using hand-placed mortars or sprayed concrete may be necessary if defects are found
59
Q

What are clay hollow pot floors and why are they problematic?

A
  1. Hollow clay pots (tiles) were first used early in the 20th Century as a means of constructing fire-proof floors and reducing some of the dead loads of solid construction
  2. The pots were separated with a clay spacer, and steel reinforcement bars were placed within the gap this formed, with a concrete structural topping being laid over the top of the pots and filling the gaps between
  3. Poor compaction (similar to the problem with woodwool slab) between the pots can lead to voiding and a lack of cover around the reinforcement, reducing the floor’s fire resistance, durability and strength
60
Q

What is mundic concrete and why is it problematic?

A
  • Concrete blocks and concrete manufactured from waste products from Cornwall/Devon’s mining industry, which contained unstable sulphides (pyrite being the main culprit)
  • In damp conditions, pyrite oxidises and produces sulphuric acid, which reacts with the cement binder and deteriorates the concrete blocks, causing a loss of integrity
61
Q

What guidance is available in relation to mundic concrete?

A

RICS guidance note ‘The Mundic Problem’ provides extensive guidance into identification and testing

62
Q

What remedial work should be considered where mundic concrete has been identified?

A

There are no current remedial measures for properties that have already suffered deterioration of mundic concrete other than removal and reconstruction, however any unaffected mundic blockwork should be kept dry

63
Q

What are brick slips and why are they problematic?

A
  • Popular in the 1960s and 1970s, brick slips were used as a method of concealing the exposed edges of a concrete frame
  • Lack of soft joints between the brick slip and structure meant that movement in the concrete (shrinkage) and brick slips (expansion) causes poor adhesion resulting in risks to health and safety as they are forced off the building
64
Q

How do modern brick slips ensure problems typically associated with brick slips are addressed?

A

Modern brick slips rely on flexible adhesives that give the bond an element of elasticity (a premixed workable mortar can then be applied in a process similar to cake icing)

65
Q

What is clinker concrete and why is it problematic?

A
  • Typically used in the late 19th and early 20th Century for fire resisting floor with steel joists
  • In damp conditions, it produces sulphuric acid from combustion products and unburnt coal in the clinker
  • The acid then has a corrosive effect on the steel joists, leading to loss of section
66
Q

What are CFCs and why are they problematic?

A
  • First produced in the 1930s as a substitute for hazardous gases used in refrigerators
  • Discarded CFC gases from fridges, cooling equipment, aerosols and building materials were found to collect in the stratosphere and catalyse the destruction of the ozone layer
  • CFCs used as refrigerants are denoted by codes (such as R-12, R-113 and R-22) depending on the gas type
67
Q

What are the main problems associated with composite panels?

A
  • Composite panels are a sandwich construction of which two outer layers of steel or aluminium sheet enclose an inner core of an adhesive-bonded lightweight material, e.g. polyurethane foam (PUR), polyisocyanurate foam (PIR), expanded polystyrene (EPS)
  • These materials can burn fiercely, give off thick black smoke and produce burning droplets that can fall on whatever lies beneath, making them very difficult to deal with
68
Q

What is the key difference between PIR foam and PUR foam used in composite panels?

A

The fire resistance is significantly lower in PUR (degrades at 250°C) than in PIR (degrades at 400°C)

69
Q

What is GRC and why is it problematic?

A

GRC (Glass Reinforced Concrete):

  1. Commonly used in external cladding panels, glass fibres are added into the concrete mix to increase tensile strength without the need for reinforcement (making the material lighter)
  2. Over time, the alkalinity of the concrete degrades the glass fibres, resulting in a loss of strength and can cause bowing of the panels
  3. Alkaline-resistant fibres are now used which offer a much better life-expectancy
70
Q

What is MMMF and why is it problematic?

A
  1. Generic term for fibrous material typically used in insulation wool
  2. Evidence suggests that MMMF is carcinogenic (however not proven)
71
Q

What are PCBs and why are they problematic?

A
  • Chemical produced from about 1929 until mid-1970s for use within transformers, capacitors, hydraulic oils, adhesives and paints
  • PCBs are toxic and are harmful to the environment (as they are very hard to break-down), and they can cause cancer in humans
72
Q

What is RAAC and why is it problematic?

A
  • From the late 1950s until 1982, RAAC planks were commonly used as roof decks, floors, internal partitions and vertical cladding panels as a lightweight alternative to standard concrete
  • Investigations by the BRE concluded that RAAC planks had a life expectancy of 30 years and would crack and deflect as a result of the reinforcement ‘slipping’ within its cover over time
73
Q

What is tesserae and why is it problematic?

A
  • Small ceramic, stone, marble or glass tiles bonded to a rendered backing used as an external finish in buildings between the 1960s and 1970s
  • Over time, adhesion failure of the background render can cause large heavy ‘plates’ of material to become loose and fall from the building
74
Q

What is UF foam and why is it problematic?

A
  • Mainly used in cavity wall insulation
  • Evidence suggests that UF Foam is carcinogenic (however not proven)
  • Also, when poorly installed it can cause the passage of water from the external to the internal leaf
75
Q

How can hair plaster be harmful within buildings?

A
  • The use of animal hair to reinforce plaster was a common technique in older buildings
  • Hair products imported into the UK pre-1919 could have been taken from animals infected with anthrax, which can be passed onto humans through inhalation or contact with a skin wound
76
Q

How can toughened glass be harmful within buildings?

A
  • Nickel sulphides present during the manufacture of glass can expand and cause glass panels to spontaneously fracture when toughened (or tempered) due to the heat treatment it receives
  • Toughened glass should therefore be avoided in sloped overhead applications (not usually a problem in vertical applications as the expansion of the glass holds it within its frame)
77
Q

How can problems with toughened glass be mitigated?

A
  • Using laminated toughened glass or applying safety film to existing panels should be considered
  • ‘Heat soaking’ (subjecting the glass to accelerated elevated temperatures) can be used during the manufacturing of glass to initiate immediate failure before it is installed (has an approximate 90% success rate)

1. Building Pathology (7 decks)

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