Concrete is a binding material that has been used for hundreds of years to build different kinds of buildings and infrastructure. Concrete has gone through numerous changes over the last few decades despite its appearance looking almost the same. These changes include the development of environmentally friendly concrete products.
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A Brief History Of Concrete
Ancient Babylonians and Assyrians used clay as their binding material to build their houses, tombs, and other infrastructure. Ancient Egyptians developed an even more sophisticated bonding substance that closely resembles today's concrete mixture. The Egyptians used lime and gypsum as binders, which is typical of today's concrete.
Lime, which is chemically called calcium oxide, was derived from either limestone or chalk or in the form of oyster shells and continued to be the main pozzolanic or cement forming agent up until the early 1800s. The ancient Greeks used concrete to build various structures such as archways, their tombs, and other structures which are still in existence now.
This primitive mixture was composed of quicklime, volcanic ash, and pumice that were crushed together to form concrete. In the year 1824, an inventor from England known as Joseph Aspdin burnt and ground together a mixture of limestone and clay, producing a mixture that is now known as Portland cement.
The mixture has continued to be the dominant cementing agent used in the production of cement even today. Over the past few years, concrete has gone through a remarkable evolution which now makes it a more spreadable mixture ideal for different kinds of jobs.
Composition And Durability of Concrete
Concrete is widely used today to build any kind of structure because of its strength and durability, from skyscrapers to storage dams and cooling towers or stacks. Aggregates are designated as either coarse or fine with respect to their specific ranges.
The aggregate material must be free from any admixture with soft particles, especially vegetable matter. Even the smallest organic soil components will result in chemical reactions that can seriously compromise the strength of the concrete. The characteristic of concrete depends on the type of aggregate or cement used to produce it.
The properties of ordinary structural concrete are largely determined by the ratio of water to concrete. The lower the water content or equal to the cement ratio, the stronger the concrete will be. The mixture must have just enough water to allow each of the aggregate particles to be surrounded by a cement paste, such that the airspaces between aggregate particles are filled with water and that concrete is fluid enough to be spread effectively and even be poured easily. The amount of cement with respect to the aggregate is another durability factor. It is expressed as a 3 part ratio, cement to coarse to fine aggregates.
The units used to measure concrete durability is the kilogram per square centimeter or the pound per square inch. The concrete strength is usually affected by environmental factors such as moisture and temperature. If the concrete is not allowed to dry adequately or is dried prematurely, the concrete will experience unequal tensile stresses.
During the curing processes, the concrete is deliberately kept damp for some time after it has been poured to slow the shrinkage that occurs as the concrete hardens. Calcium chloride is added to accelerate the setting process to generate enough heat to counteract the mildly low temperatures. Very large concrete forms that cannot be adequately covered are usually not poured in very cold or freezing temperatures.
Reinforced Concrete Composition
Reinforced concrete is concrete that has been hardened into embedded steel. This invention is attributed to a Parisian gardener called Joseph Manier who made garden pots and tubs out of concrete that he reinforced with mesh, and he received a patent in 1867.
Reinforced steel, which can take many forms including bars, rods, or mesh, largely contributes to tensile strength. Ordinary concrete cannot withstand stresses such as strong winds and vibration or even earthquakes without failing.
The tensile strength of steel and the compressional strength of concrete in reinforced concrete can render a member that is capable of sustaining very heavy stresses of different kinds. Concretes fluidity mix enables it to place the steel at points where the greatest stress is anticipated
Attempts To Produce Carbon-Neutral Concrete
Concrete production has greatly improved over the decades, allowing for new types of compositions to be formulated and concrete to remain a versatile component at multiple building sites.
High-performance concrete has been invented which allows engineers and contractors to rely on this type of concrete for building bridges where durability is vital.
Concrete is the second most used material after water on earth and it accounts for 7% of the global emissions. Concrete action for climate change is an initiative that aims to drive the transformation of the concrete industry to a more sustainable way of producing concrete. Targets have been set for 2050 to deliver carbon-neutral concrete by the Global cement and concrete association (GCCA). It brought together 40 of the world's leading cement manufacturers to sign up and bring measures to reduce their carbon footprint in their daily operations to achieve this target.
New studies are also developing new forms of concrete that have a reduced carbon footprint:
Calcium Carbonate Concrete: Building on Recycling
Further Reading And Reference
Knightscompanies.com.How Concrete Has Changed Over the Last 50 Years | Knights Companies. [online] Available at: <https://www.knightscompanies.com/blog/concrete/how-concrete-has-changed-over-the-last-50-years/>
Ouellette, J.,Noblewoman’s tomb reveals new secrets of ancient Rome’s highly durable concrete. [online] Ars Technica. Available at: <https://arstechnica.com/science/2022/01/noblewomans-tomb-reveals-new-secrets-of-ancient-romes-highly-durable-concrete/>
Encyclopedia Britannica.concrete | Definition, Composition, Uses, Types, & Facts. [online] Available at:<https://www.britannica.com/technology/concrete-building-material>
Concrete Supply Co. Concrete Basics: Essential Ingredients For A Concrete Mixture | CSC. [online] Available at: <https://concretesupplyco.com/concrete-basics/>
Cement.org. n.d. Durability. [online] Available at: <https://www.cement.org/learn/concrete-technology/durability>
World Economic Forum. 2021. A net-zero world needs zero-carbon concrete. Here's how to do it. [online] Available at: <https://www.weforum.org/agenda/2021/07/a-net-zero-world-needs-net-zero-concrete/>