Materiality
Wood
The use of timber as a construction material dates back to the Neolithic Period, when oak timbers were used for the wooden lining of water wells in Germany. Throughout medieval times, wood became an essential element in house construction, and half-timber constructions, such as Little Moreton Hall, became increasingly popular. In the Renaissance period, ornate wooden elements were used in interior design, while in the Baroque era, wooden carvings and mouldings were introduced.
Softwoods come from coniferous trees and include pine, cedar, and spruce. Pine is lightweight and easy to work with, while cedar is naturally resistant to rot and insects, making it a good choice for outdoor projects. Spruce is lightweight and strong, making it suitable for construction projects. However, softwoods are not as durable as hardwoods and can be prone to warping and splitting over time.
Hardwoods come from deciduous trees and include oak, maple, and mahogany. Oak is durable and resistant to wear and tear, while maple is strong and stable, making it less prone to warping and shrinking. Mahogany is strong and durable, with a unique and rich colour. However, hardwoods can be heavy and difficult to work with.
Modern design has introduced various fabrication techniques for wood, including board form concrete, which imprints concrete with a wood grain image, Glulam beams, which are laminated thin wood veneers that offer improved strength and stability, laminate, a composite material made by bonding multiple layers of wood veneer with resin, and engineered wood products such as plywood, particleboard, and laminated veneer lumber, which offer improved strength and stability compared to solid wood.
Metal
Steel is a highly versatile construction material that has various properties that make it useful for a wide range of applications. It has a density of approximately 7,800 kilograms per cubic meter and is highly thermally conductive, making it ideal for applications where heat transfer is important. Additionally, steel is magnetic and can be magnetized, which makes it suitable for applications that require magnetic properties such as electric motors and generators.
Strength is another essential characteristic of steel. Compared to other building materials like wood or concrete, steel has a high tensile strength, which means that it can be stretched or pulled without breaking. Its hardness also makes it resistant to wear and tear, which contributes to its long lifespan. Steel also has a high level of elasticity, which means that it can be bent or deformed without breaking, making it useful for applications that require flexibility.
Hot-rolled steel and cold-rolled steel are two different types of steel that are produced using different processes. Hot-rolled steel is produced by heating a steel slab above its recrystallization temperature and then rolling it into the desired shape and thickness. This process causes the steel to become more ductile and malleable, making it easier to shape and form. However, the surface of hot-rolled steel is usually rough and uneven. On the other hand, cold-rolled steel is produced by rolling steel that has been cooled to a temperature below its recrystallization temperature. This process makes the steel more rigid and brittle than hot-rolled steel but also results in a more uniform and smoother surface. Although cold-rolled steel is more expensive, it is 20% stronger than hot-rolled steel.
Masonry
Masonry materials like brick, stone, and concrete blocks have varying densities, with brick typically having a lower density than stone or concrete blocks. Brick masonry is held together by mortar and grout, making it a homogeneous construction. The performance of a structural masonry element depends on the properties of the constituent materials and their interaction as an assemblage.
Different types of mortar are recommended for specific masonry applications. Type N mortar is suitable for general use in exposed masonry above grade, while Type S mortar is recommended for use in reinforced and non-reinforced masonry where maximum flexural strength is required. Type M mortar is specifically recommended for masonry below grade and in contact with the earth, such as foundation walls, retaining walls, sewers, and manholes.
Absorption is the amount of water a material can absorb, expressed as a percentage of its weight. This can affect the durability and performance of masonry materials in wet environments. For clay bricks, the acceptable water absorption is between 12% and 20%. The closer the absorption is to 12% for engineering bricks, the better the result will be. If the water absorption is too low, i.e., below 12%, it may be difficult to obtain a proper bond between the mortar and the bricks.
Glass
Glass is a versatile material that has been used in architecture for thousands of years, from the discovery of glass blowing in the 1st century in Europe to the invention of the float glass process in 1958. Glass has various properties that make it ideal for use in buildings, such as transparency, workability, and recyclability. It is also a sustainable material that has excellent energy-saving properties and can reduce electricity bills while providing ample natural light. Performance parameters of glass such as visual light transmission, solar factor, U-value, and internal reflection make buildings more efficient and ecologically viable. Additionally, glass can be laminated or admixed to increase its strength and enhance acoustic control. Overall, glass has become an integral part of modern-day architecture, providing not only see-through properties but also the desired structural strength to be used in facades.
Float glass is made from raw materials including silica sand, soda ash, limestone/dolomite, feldspar, and cullet. These materials are melted in a furnace and then poured onto a bed of molten tin to create the flat, smooth surface of the glass.
Plastics
Plastics are synthetic materials derived from petrochemicals, which are used extensively in the construction industry. They are strong, lightweight, durable, and easy to install. Plastics also have a wide range of design possibilities, and come in a variety of colours. They are poor conductors of heat and electricity and can be recycled.
However, plastics have limitations and disadvantages as well. They may be degraded by sunlight, and many types of plastics are flammable unless treated. Plastics also have a high embodied energy content and a low modulus of elasticity, which makes them unsuitable for load-bearing applications. They can soften at moderate temperatures and have a high thermal expansion, requiring adequate thermal movement in detailing. Finally, many plastics are not biodegradable and can cause pollution when they accumulate.
Plastics are used to create a variety of products in the construction industry, including pipes, cables, floorings, domes/skylights, roofing, windows and doors, storage tanks, hardware accessories, temporary structures, and insulation materials.
Concrete
Plastics are synthetic materials derived from petrochemicals, which are used extensively in the construction industry. They are strong, lightweight, durable, and easy to install. Plastics also have a wide range of design possibilities, and come in a variety of colours. They are poor conductors of heat and electricity and can be recycled.
One of the main advantages of concrete is its strength and durability. It can support heavy loads and resist compression and tension forces, making it an ideal material for load-bearing structures. Concrete can also withstand environmental factors such as fire, water, and extreme temperatures. One major issue is its environmental impact, as the production of cement is responsible for a significant amount of greenhouse gas emissions. Concrete also has a high embodied energy content due to its production process, and its disposal can be difficult and expensive.
In terms of design, concrete offers limited possibilities compared to other construction materials. Its appearance is typically grey and uniform, although it can be stained or painted to add colour. Concrete is also heavy and requires specialised equipment for transportation and installation.