Concrete is one of the most widely used construction materials across the globe. Used to create structures of all sizes and designs, from small, decorative sculptures to some of the most jaw dropping mega structures, concrete is unarguably one of the most versatile building materials used today. But what makes concrete so adaptable to so many environments and styles of building? Well, it all comes down to its composition, let’s explore more below:
In its most basic form, concrete is comprised of three essential ingredients: cement, water and aggregates. These three ingredients are adjusted to create varying consistencies to suit a range of applications. For more advanced mixtures, admixes are incorporated into this basic recipe to give concrete improved properties. The admixtures in concrete vary depending on the desired application but some of the most common include: small fibres (steel or fibreglass) and water reducers to improve strength or cracking, accelerating admixtures for faster setting and air through air entraining, for improved workability and durability.
The workability and strength of a concrete mix can also be adjusted without the need for admixtures. A basic level concrete mix: water, cement and aggregate, can be adjusted to produce different type of concrete by changing the type of aggregate or cement used as well as the water to cement ratio. In structural concrete, less water is required to produce a stronger mixture.
What Part Does Each Ingredient Play?
Each ingredient in every basic concrete mix plays an essential role in the end product, let’s take a look at the purpose and behavior of each vital ingredient below:
Water
Water is the hydrator in every concrete mix. When mixed with cement, it forms a workable paste that is the base of every concrete mix. The less water used, the stronger the concrete will be however the formula is not always that simple. When we reduce the water content of a concrete mix we also reduce the workability and adhesion qualities. This is why many mixed incorporate a water reducer admixture, to retain the workability while still increasing the strength.
Cement
Cement is the binding agent in concrete. It is created by heating natural, sedimentary rock such as limestone and minerals such of clay and then crushed into a fine powder. As the cement and water mixture coats the fine aggregate particles the mixture hardens and strengthens to form concrete.
Aggregates
Aggregates (gravel, stone, sand) make up around 60% to 80% percent of any concrete mix. They are an essential bulking agent but also give the concrete its compressive tensile strength, which is what makes concrete to capable of supporting heavy loads without breaking or fracturing. However, with that being said, the size, shape and type of aggregate used also plays a huge part in a mix strength. Smaller and finer aggregates produce stronger concrete mixes. In some cases and for mixes where extremely high strength concrete is needed, the amount of aggregate will be reduced and more cement will be added, which will increase the manufacturing and cost price of the mix.
