Degradation of construction materials
Contents |
[edit] Introduction
Construction materials can be very durable but there are many cases of building materials failing prematurely. All building materials can suffer from deterioration and decay if they are not protected and maintained correctly. Common reasons for the degradation of construction materials include:
[edit] Natural agents
Some materials can decay due to natural processes including:
- Ageing- natural deterioration over time from wear and tear.
- Weather – exposure to the elements over time caused for instance by wind, frost and rain.
- Timber decay- including dry rot, insects, wet rot and fungal attacks.
- Ultraviolet light – radiation from sunlight exposure.
[edit] Moisture
Moisture penetration can cause damage to wood fibres and materials such as plaster, brickwork, concrete and stonework. Capillary action causes water to move through materials and this can result in deterioration.
[edit] Shrinkage
Shrinkage generally occurs in timber. Freshly felled timber will contain significant amounts of moisture, but when used in construction it is likely to dry and shrink, causing cracks and gaps in the timber itself, especially in very dry areas.
Conversely, kiln-dried timber can expand when used in areas with high humidity. The best method to avoid the size changes in timber is to allow it to acclimatise to the conditions in which it will be used, before installation.
[edit] Exposure conditions
Exposure conditions might include:
- Weathering - the combined action of the elements, such as rain, wind, frost and sunlight.
- Thermal ageing - in high temperatures the chemical processes involved in material degradation can be accelerated.
- Humidity – extreme levels of humidity can have an expediting effect on the degradation of materials.
[edit] Corrosion in metals
Corrosion in metals is the result of chemical processes, typically when the metal is exposed to liquid. The most common occurrence of corrosion in metals is oxidation, which causes rust in iron.
[edit] Loading
Loading conditions causing degradation can be classified as:
- Shock – dynamic loads causing impact in low toughness materials.
- Static – can cause creep deformation in materials over time.
- Cyclic – constant varying dynamic loading can cause fatigue in materials.
[edit] Chemical
All materials are generally susceptible to chemical degradation. This can be caused by:
- Alkalis – especially when alkaline cement paste and silica-based aggregates react and can cause cracking.
- Sulphates – sulphates can be present in water and can react with concrete and cause levels of stress.
- Leaching – some porous materials can be susceptible when minerals are dissolved in liquid solutions which will, in turn, weaken materials.
- Acid rain – pollution in the atmosphere combines with water and forms acid rain. This rain can dissolve calcite in marble or limestone.
[edit] Related articles on Designing Buildings Wiki
- Construction materials.
- Defects.
- Deterioration.
- Dry rot.
- Failure of cast iron beams.
- Failure of metals.
- Graphitisation.
- Hydrogen embrittlement.
- Marine corrosion.
- Meassures to minimise material degradation.
- Mould growth in buildings.
- Rust.
- Schedule of defects.
- Stain.
- Structural failures.
[edit] External references
BTEC National Construction Student Book, Pearson
Featured articles and news
Types of building sensors on BD
From biometric to electrical current, chemical and more.
Government mandates detectors in rented homes
Changes are due to come into force on 1st October 2022.
80% of major government projects are rated red or amber
Heed advice and insight of this report IPA tells the government.
The end of the games but continued calls for action
From the Commonwealth Association of Architects.
CIOB respond to the government call for evidence
For the Levelling Up, Housing & Communities Committee.
How are buildings and their occupants responding to extreme heat?
BSRIA's Technical Director reflects on recent weather patterns.
Landownership in England in 1909
A national valuation to fund old-age pensions.
The world’s largest Commonwealth memorial to the missing.
Long after the end of the defects liability period.
BSRIA Occupant Wellbeing survey BOW
Occupant satisfaction and wellbeing in buildings.
Geometric form and buildings in brief
From the simple to the complex.
Understanding the changing nature of insulation
And the UK Government guidelines.
Three year action plan to improve equity, diversity and inclusion
Commitment agreed to by major built environment bodies.
The Construction Route – what needs to change?
Electrical skills, low carbon, high-tech and the building services revolution.
Deep geothermal power possibilities
Ultra-deep drilling with millimeter-wave beam technology.
BSRIA Briefing 2022- From the outside looking in
Looking at the built environment from space.
Competence requirements for principal contractors and designers
BSI standards 8671, 8672 and 8673.
Bringing life to burial grounds.
From failed modernism to twenty-minute neighbourhoods.
Design chill and design freeze
The gates process and change control.
Comments