Why is Concrete Important?

This article will answer the question “Why is concrete important?” and will discuss topics such as the synergistic role of concrete materials to concrete strength, and relevant developments in concrete technology like green concrete, self-leveling, and fiber-reinforced concretes.

 Why is concrete important?

Concrete is important because of its various applications in the construction industry which ultimately affects the quality of human life. The rise of several infrastructures and building developments indicates capital expenditures to expand businesses that create jobs for the people. Modern societies live in high-rise condominiums and other residential spaces. As living spaces are one of the basic needs of a functional society, concrete is deemed to be an important asset in the industry. 

Synergistic Role of Concrete Materials to Concrete Strength

One of the reasons why concrete is considered as a remarkable building material is its excellent compressive strength which can be traced back to proper curing methods and synergistic roles played by its components. Concrete is actually a composite building material made of cement, water, aggregates, and sometimes admixtures (depending on the structural requirement). Each of these materials has a contributing function in the structure.

Cement

The most ubiquitous cement in the industry is Portland Cement which is manufactured by an energy-extensive process of kilning. In this process, the raw materials such as clay and calcium carbonate underdo a particle-size reduction, mixing, and finally a calcination reaction at an extremely high temperature. The final products of this reaction (and hence the components of Portland cement) are silicates and aluminates such as tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite.

The main function of cement in concrete mixture is a binding paste to its components. It bonds large aggregates and sand to form a durable matrix that will last for a long period of time.

Water

Water serves a crucial role in the curing process of concrete structures. Curing is a chemical reaction (specifically a hydration reaction) which consumes water molecules to produce crystals and minerals that strengthens concrete matrix. As water is directly used in the reaction, a standard level of water content in concrete mixture is established based on the specificity of project requirements. Generally, a very high amount of water is not advisable as this results in shrinkage that makes the structure vulnerable to crack damages.

Aggregates

Aggregates are granules of rock particles like gravel, crushed stones, sand, and furnace slag which are graded according to particle size. The two types of aggregates are fine and coarse aggregates wherein the former refers to particles that passed through the opening of sieve #4 while the former are particles that are retained.

High-grade aggregates have a high packing density and are highly favored when selecting concrete materials. High packing density implies that the aggregate is more compact and has minimal voids, requiring less amount of cement to bind the mixture. Because aggregates comprise more than half of the total composition of a concrete mixture, most of the mechanical properties of the hardened structure relies on this material. Hence, it is a prerequisite to assess the aggregate quality required by the project.

Admixtures

While water, cement, and aggregates are the main components of concrete, admixtures may be added to the mixture to enhance the properties of the resulting mixture. Some of the most common admixtures used for concrete are air-entraining agents.

The purpose of air-entraining agents is to improve the resistance of concrete against stress induced by being exposed in freezing temperatures. Because concrete mixtures have water all throughout the matrix, low-temperature environments freeze the water to form ice. The transformation of liquid water to a solid ice implies volume expansion that could fracture the structure due to lack of sufficient spaces for the additional volume. Through air-entraining chemicals, the matrix will entrain just the right amount of air to create voids for the ice formation. 

Other Concrete Developments

Several ongoing movements have been initiated by the research and development sector to improve concrete as a product and to address its negative impact against the environment.

Green concrete

It is common knowledge that concrete is a widely utilized building material across the globe, and its demand continually rises to suffice the demanding need of business ventures and their expansion. While new infrastructures may reflect an active economy, the production of concrete is unsustainable as it releases large amounts of greenhouse gases into the atmosphere. These gases contribute to the rise of global temperature to a critical level, so the need to innovate concrete as a building material is a top priority.

One of ways to address this concern is by utilizing alternative cementitious materials such as fly ash and blast furnace slag. The utilization of these two materials is also economical as they are considered waste from coal-burning plants and steel plants, respectively. Apart from using waste by-products, green concrete is seen to also utilize second-hand concrete as aggregates to fresh mixture in order to provide ways to manage the accumulating waste from the building industry.

Self-leveling concrete

Self-leveling concretes are specifically designed to have an impressive workability without compromising the mixture from segregation. Workability refers to how easily the concrete mixture can be casted into various forms and shapes, implying the role of water content in the property. Traditionally, adding more water to the mixture improves the workability of concrete, but the method could result in shrinkage in the long run.

The technology of self-leveling concrete allows the formation of concrete mixture of low viscosity without the need for additional water, thereby increasing the strength of the structure. From its name, this material can be used to create leveled surfaces such as floorings of residential floorings as well as driveways.

Fiber-reinforced concrete

The technology behind fiber-reinforced concrete or FBR is the utilization of fiber mixtures such as polymers, glass, and metal as reinforcement to the structure. The even distribution of the reinforced fibers all throughout the matrix improves the mechanical properties of the structure such as ductility and tensile strength which makes it qualified for application in industrial slabs.

Conclusion

This blog post answered the question “Why is concrete important?” It was clearly explained in this article that concrete is important because it plays a vital role in the construction industry which directly affects the quality of human life. It was emphasized that concrete is a staple concrete building material because of its remarkable properties which are synergistically brought together by its components. Finally, this article discusses a few relevant developments in concrete technologies such as green concrete, self-leveling, and fiber-reinforced concretes.

For any questions and suggestions about this article, please feel free to submit your thoughts in the comment section below.

Frequently Asked Questions (FAQs): Why is Concrete Important?

Why is curing of concrete required?

Proper curing of concrete is important in its overall development because it directly affects its long-term structural stability. Allowing fresh concrete mixture to react for a certain period of time with an appropriate level of water content avoids crack damages and porous hardened concrete structures.

Why is concrete durability important?

The durability of concrete is important because concrete structures are expected to remain stable for a lot of years. Large structural projects such as buildings and skyscrapers will not be economical if the resulting concrete requires regular maintenance when its durability is in question.

 Is it OK if it rains after pouring concrete?

It definitely depends on how strong the rain will be. While curing requires proper hydration which rain could deliver, having too much rain of large droplet size could ruin the slab surface of your project as well as compromise the integrity of the structure in the long run. Too much water in your concrete mixture is not good in terms of durability and stability of hardened concrete.

What happens if you put too much cement in concrete?

While increasing the amount of cement in your concrete mixture could directly increase in its strength, it is important to note that this technique strengthens the structure to only some extent. In other words, increasing the cement but not too much as very high amounts of cement in your mixture result in a highly brittle structure which no one anticipates in a structural project.

Does gravel make concrete stronger?

 Yes, using gravel as coarse aggregate in your concrete mixture could increase the strength of your final concrete structure. Because aggregates account for approximately 80% of your concrete’s volume, its presence affects the structure’s mechanical properties which dictates how strong the concrete could be.

How do you make concrete stronger?

Making concrete stronger largely greatly depends on the mixture design, specifically the water cement ratio. A very high ratio results in a structure that is highly vulnerable to shrinkage and cracks whereas an extremely low ratio makes a brittle concrete. In addition, depending on the purpose of your project, one may utilize reinforcements to increase the strength of the structure.

BIBLIOGRAPHY

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Bentur, A.; Igarashib, S.-I.; Kovler, K.: Prevention of autogenous shrinkage in highstrength concrete by internal curing using wet lightweight aggregates. Cem. Concr. Res. 31, 1587–1591 (2001)

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Lacombe, P., Beaupré, D. & Pouliot, N. Rheology and bonding characteristics of self-leveling concrete as a repair material. Mat. Struct. 32, 593–600 (1999). https://doi.org/10.1007/BF02480494

Lima C., Faella C., Pepe M., Martinelli E. (2017) Cement Replacement: Experimental Results for Concrete with Recycled Aggregates and Fly-Ash. In: Barros J., Ferrara L., Martinelli E. (eds) Recent Advances on Green Concrete for Structural Purposes. Research for Development. Springer, Cham. https://doi.org/10.1007/978-3-319-56797-6_3

Martinelli E., Koenders E.A., Pepe M. (2017) State of Knowledge on Green Concrete with Recycled Aggregates and Cement Replacement. In: Barros J., Ferrara L., Martinelli E. (eds) Recent Advances on Green Concrete for Structural Purposes. Research for Development. Springer, Cham. https://doi.org/10.1007/978-3-319-56797-6_1

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