CM 155: Building Science - Properties of Materials

A collection of vocabulary flashcards covering basic, physical, mechanical, chemical, moisture, and fire properties of building materials based on the CM 155 Building Science lecture.

Simple property

A basic property of a material, such as mass and length.

Complex property

A property that can be broken down into basic components, such as the quality of a material.

Three basic material requirements

The three essential requirements that all building materials must satisfy: Functional, Aesthetics, and Economic.

Functional properties

The set of properties concerning a material's purpose and usefulness, comprising physical, mechanical, chemical, and biological properties.

Physical properties

The make-up of a material that gives it unique characteristics, including characteristics based on its independent nature and those observed when responding to conditions in use.

Mechanical properties

Properties describing a material's ability to resist deformation and breakdowns of all kinds under the action of external forces (e.g., hardness, elasticity, brittleness, ductility, creep, yield, abrasion resistance).

Chemical properties

The ability of a material to withstand attacks by a corrosive environment that can destroy the material, such as acid and alkali resistance.

Biological properties

Properties relating to a material's resistance to living organisms such as insects and fungi, which is especially important in timber construction.

Porosity grouping

The classification of building materials based on porosity ($p$): Low porosity ($p$ below $30\%$), Medium porosity ($p$ between $30\%$ and $50\%$), and High porosity ($p$ above $50\%$).

Voids ratio

The ratio of the volume of voids to the volume of solids in a sample of a material.

Hygroscopicity

The ability of a material to take up water from the atmosphere, dependent upon the material's structure and the number and sizes of its pores.

Water absorption

The ability of a material to absorb and retain water, quantified as the amount of water absorbed when fully submerged.

Water absorption by mass ($A_m$)

The percentage of water absorbed relative to dry mass, calculated as $A_m = \frac{(m_i - m) \times 100}{m}$, where $m$ is the dry mass and $m_i$ is the water-saturated mass in grams.

Water absorption by volume ($A_v$)

The percentage of water absorbed relative to total volume, calculated as $A_v = \frac{(m_i - m) \times 100}{V}$, where $m$ is dry mass, $m_i$ is saturated mass in grams, and $V$ is the sample volume in $cm^3$.

Swelling capacity

The ability of some materials to expand as they absorb water.

Moisture resistance

The ability of a material to withstand for a long time the destructive effect of cyclic wetting and drying; describes the ultimate strength of a material.

Permeability

The unit amount of liquid or gas that diffuses through a unit cross-section area of a certain thickness under a specified pressure difference.

Permeability to water

The ability of a material to allow water to pass through it under pressure, which increases with larger capillary diameters.

Relative humidity

The amount of water vapour in the atmosphere at any given temperature expressed as a percentage of the maximum amount of water vapour that can be held at the same temperature.

Dew point temperature

The temperature at which air comes in contact with an object where water vapour will change to a liquid state as saturation occurs at $100\%$ relative humidity.

Condensation

The process that occurs when water changes from its gaseous state to its liquid state, deposited on any surface that is cooler than the dew point.

Fire-resistance rating

The time in hours ($h$) of exposure to fire before a material or structural component suffers a loss of strength.

Combustible materials

Materials that catch fire and burn, such as wood, bitumen, tar, and polymers.

Non-combustible materials

Materials that do not burn when subjected to fire, such as clay brick, tile, asbestos-cement materials, and most concretes.

Shrinkage

An undesirable change in size (linear or volume) undergone by a material as a result of certain processes, such as variations in moisture content.

High-strength steel

An alloy of iron with a touch of carbon that is strong in compression and tension, but rusts and loses strength at extremely high temperatures.

Aluminium alloy

A material composed of aluminium with magnesium and copper that is lightweight, rust-resistant, and strong in compression and tension, but expensive.