Material Research 

Steel 

Steel is made from Iron Ore, Coke, and Limestone, which are all melted in a blast furnace, resulting in molten iron. From here, there are two processes that can be used to manipulate this composition of materials to make steel – Basic Oxygen Steelmaking (BOS) and Electric Arc Furnaces (EAF). In the BOS process, recycled steel is added to the molten iron in a converter. Once it has reached high temperatures, oxygen is then blown through the metal which results in reduces carbon content. The EAF process feeds recycled steel through high power electric arcs at up to 1650 degrees Celsius. This then melts and converts the composition to high quality steel. Another process is called secondary steelmaking. This process treats molten steel from BOS and EAF processes to adjust the composition of materials within, by adding or removing elements or by changing the temperature and production environment (Bell, T. 2020).

 

To form steel into shapes, there are two well-known methods. These methods are hot and cold rolling. Hot rolling is a process that involves rolling a sheet of steel at temperatures above its recrystallization point. This point is typically above 537 degrees Celsius. When heated past this point, the metal becomes malleable and can be easily formed and shaped, which allows for the ability to produce larger quantities. The steel is then cooled to room temperature which normalises it. As the steel cools however, it will also shrink. Hot rolled products are typically used for structural components and other products such as rail tracks, I-beams, agricultural equipment, sheet metal and automotive frames.

 

Cold rolled steel is pressed with a roller at room temperature. Cold rolled steel has 20% more strength when compared to hot rolled steel due to strain hardening. Products made through cold rolling are shaped through breakdown, semi-finishing, sizing, semi-roughing, roughing and finishing. One advantage to cold rolled steel is that it does not shrink as it is already at room temperature. Cold rolled products are typically strips, bars, rods, home appliances, roof and wall systems, metal furniture and aerospace structural members (National Material Company, 2020).

 

A portal frame construction consists of a steel structural frame that is made created using beams or rafters supported at either end by columns. The fixings between beam and columns are rigid, allowing for the beams movements to transfer to the columns. Portal frames were developed during WW2, however they become more popular during the 60s. Today, portal frame construction is used for wide span warehouses, agricultural buildings, hangers, factories, large retail units, etc.

 

Within the building industry, there are a vast variety of steel products used. Examples include girts and purlins, as well as walling and roofing products. Girts and purlins are very similar, though they are used for different things. Girts are the horizontal structural members within a framed wall in which provides support to the wall. Purlins act in the same way for roof panels. There are two common types of girts and purlins; Z girts and purlins and C girts and purlins, and they take the shape of the letter their name describes. Z shapes can be lapped as they are asymmetrical. This adds structural continuity, saves on material costs and increases strength of the structure. On the other hand, C shapes can not be lapped, however they do allow for easy packing and transport given their stable shape. C shaped purlins and girts are preferred for when providing stability in single spans (Whirlwind Steel, 2018).

 

Building with steel for the walls of the structure adds a number of benefits. Steel is a strong, durable and easy to install material, it is thermally efficient and it is compliant for use within bushfire zones. Building with steel for roofs offer much the same benefits. There are reduced heating and cooling costs with the decrease for the need to use air conditioners, products made in steel are lightweight and have longer spans, they are low maintenance and are corrosion resistant (Steeline, 2020).

One thing to consider when building with steel is galvanic corrosion. This occurs when two metals dissimilar from each other are immersed in a conductive solution such as water and are electronically connected. Galvanic corrosion can be prevented by a number of solutions:

• Select materials with similar corrosion potentials

• Break the electrical connection with insulation between the two metals

• Apply coatings to both metals

• Separate the metals by inserting a spacer

• Install a sacrificial anode that is anodic to both metals

• Add a corrosion inhibiter to the environment (TWI Ltd, 2020).

​

Concrete 

Concrete has been used throughout history as a building material and has contributed greatly to the building environment. Exampled of concrete can be found as far back as Ancient Egypt. Concrete structures made during the Roman Empire, which some remnants still exist from, were made from volcanic ash pozzolans mixed with mater, sand and stone. In it’s most basic form, three ingredients are needed to create concrete. These ingredients are cement, which acts as the binder, aggregates, and water. The cement reacts with the water to from a hardened silicate compounds that in turn bind all the aggregate pieces together into one material known as concrete (CCAA, 2010).

​

The slump test is a test that determines the workability or consistency of a concrete mix, either at the laboratory in which it is manufactured or on the construction site during the work process. The slump test is done for each batch made of concrete in order to check the uniform quality of the concrete during construction. In order to complete the slump test, certain items are required. These items include a mold such as a slump cone, a non-porous base plate, a measuring scale, a tamping rod and oil to apply to the inside of the slump cone. The cone is placed on the base plate and then filled with the concrete mix in four equal layers. The tamping rod is used throughout the pouring of each layer. Once the cone is filled to the top and the top is levelled with a trowel, the cone is removed from the concrete slowly. The slump of the concrete is measured by the distance the cement mix slumped to the height of the cone itself. If the slump is anything but true slump, the concrete cannot be measured and the test was a fail (Mishra G. 2020).

​

There are a number of different concrete floor construction techniques available to use. The most common is slab on ground whereby part of the ground is excavated and the concrete is poured or pumped into place. Conventional slabs include insulation that sits beneath the concrete in th form of a grid of expanded polystyrene foam pods that fill voids under the concrete and in which forms a waffle type structure beneath the concrete.

​

The properties of concrete include the ability to withstand many acids, fertilisers, water and fire, as well as being able to be finished with finished that can be glass-smooth or coarsely textured, depending on the desired design. Concrete also has a substantial amount of strength in compression, however is weak in tension. In many cases concrete is coupled with steel to lend strength in tension (2013).

​

Concrete can be transported to site and made in two ways. The first way is insitu. Using this method the concrete is poured onsite, either already in place or near its final location, which it is then moved into place. Cast in situ concrete is hard to control the mix, placement and curing, given that the environment is not as controllable as other environments (GharPedia, 2019). The other method is precast. Precast concrete is manufactured within a factory, using reusable and adjustable molds with reinforcement placed inside. The concrete is then poured into the molds, vibrated and then cured, all within the factory. Given the highly controlled environment precast concrete is manufactured in, honing, polishing and staining techniques can be specified and applied to the concrete (National Precast Concrete Association Australia, 2015).

​

Glazing 

Glass has been made and used by humans since 3100BC. Until the 1850s, glass was made by blowing techniques and hand gathering. Nowadays, the manufacturing process of glass consists of mixing sand, silica, limestone, soda ash and chemicals for colouring, which are then fed into a pot furnace or a tank furnace and are heated until the development of carbon dioxide, oxygen, sulphur dioxide and other gasses has stopped. From here, the glass needs to be fabricated. Giving the glass shape can be done by hand or by machine. The following are the ways in which glass can be fabricated: blowing, casting, drawing, pressing, rolling and then spinning.

​

BLOWING: blow pipe is used to blow air into the glass, either by the creator blowing into the pipe themselves or by an air compressor. This causes the molten glass, which has the viscosity of honey, to create the shape of a cylinder. This process is then repeated until the required shape size of the cylinder is formed.

​

CASTING: The molten glass is poured into moulds and is allowed to slowly cool.

​

DRAWING: This method involves pulling the molten glass by hand or by machine, eventually creating the desired shape.

​

PRESSING: The molten glass is pressed into moulds, where a pressure is applied by hand or by machine. This process is used more commonly when creating ornamental pieces.

​

ROLLING: To roll molten glass, there are two methods in which could be followed. The first is done by rolling the molten glass between two heavy rollers, where a flat plate of glass is created. The second method involves pouring the molten glass on to a flat iron casting table where it is turned flat with the aid of a heavy roller.

​

SPINNING: The final process in which glass can be made involves the molten glass being spun at high speed by machine. This then forms very fine glass fibres which has the tensile strength similar to mild steel. It is immune to acids, fire and vermin, is very flexible and soft and is used for insulation against heat, electricity and sound.

​

After the final shape of the glass has been created through one of the above methods, the glass is then slowly cooled down and hardens (Susmita, B).

 

The types of glass include annealed glass, heat strengthened glass, tempered or toughened glass and laminated glass. Annealed glass is formed through the annealing stage of the floating process. The molten glass is cooled under controlled conditions until it reaches room temperature, which then relieves any internal stresses in the glass. Heat strengthened glass is semi tempered/toughened glass. This process involves taking the already annealed glass and heating it back up to roughly 600-750 degrees Celsius and cooling it quickly afterwards. This process increases the mechanical and thermal strength of annealed glass. Tempered or toughened glass is the most common form of glass used in balustrades and similar structural applications. This process takes the annealed glass and heats it back up to roughly 700 degrees Celsius through conduction, convection and radiation. When cooling the glass down, the process is accelerated by a simultaneous blast of air on both surfaces of the glass. This process creates a glass product that is four to five times stronger and safer than annealed glass. Lastly, laminated glass is made by laminating together two sheets of glass (any of the aforementioned types) with 1.52mm thick Polyiynil Butyral (PVB). The advantages of laminated glass include mostly safety and security. It is highly unlikely that both of the glass panels break at the same time, and until the broken glass is replaced the second panel and the interlayer will support the first shattered panel (Brass Age, 2020).

 

Curtain walls are thin, aluminium framed walls. They contain in fills of glass and metal panels or thin stone. Curtain walls do not carry the floor or roof loads of a building (Vigener, N. et al. 2016). The most common type of glass specified for curtain walls is laminated glass, due to its higher strength and safety. It is often used also in hurricane prone regions or in areas requiring blast protection (Sanders, R.M. et al. 2017). There are three types of glass curtain wall systems: Pressure-equalised, water-managed, and face-sealed. Pressure-equalised rain screen systems are the best option for when air and water resistance is necessary. The system includes a gasket in which surrounds the face of the glass, creating a chamber with equalised pressure, forming an airtight barrier. Pressure-equalised curtain wall systems also do a good job of transferring wind loads. Water-managed curtain wall systems include drains and weeps into their construction. These systems resist water infiltration, however they do not include an air barrier, meaning a larger amount of water is forced into the curtain wall system and in turn must be weeped away. These types of curtain wall systems often result in leaks. Lastly, face-sealed curtain wall systems require perfect and continuous seals placed between each glass unit and the frame and all its members (nvision Glass, 2017).

 

Storefront systems are typically designed as flush glaze and no not include any protruding stops, creating a clean look. Within a storefront system, water is weeped away at the sill of the system (Schoeb, G. 2015). It does this through directing the water to run down the mullion between the glass panels, through a drainage cavity above the sub sill, and finally onto the exterior of the building. Storefront glazing systems are designed for high use commercial applications and can be as high as 10 feet. Typically they are only used on the ground level of a building and are fabricated on site. They typically span from the floor to the slab or structure above it and are limited to the first three floors of a structure (Craven, K. 2019).