Concrete Technology: Challenges

Concrete has been in use since Roman times. The origin of the word concrete is from the Latin word "concretus," which means "mixed together." Undoubtedly, concrete is the world's most-used construction material. It is used for highways, parking lots, aqueducts, bridges, skyscrapers, dams, homes, driveways, and numerous other applications. The key features of concrete that make it the most preferred construction material are:

Versatility
Durability
Economy

Annual worldwide concrete production is about 12 billion tons, out of which the U.S. uses about 340 million cubic yards (260 million cubic meters) of ready-mixed concrete.

Concrete is made by mixing cement, water, coarse and fine aggregate, and various admixtures. The basic aim of mixing these ingredients in measured amounts is to make concrete that is easy to transport, place, compact, and finish and that will set and harden to create a strong and durable product.

With growing demand for concrete, new challenges have been posed to concrete technologists/researchers. Recently, strong emphasis has been laid on "quality concrete" that has the following characteristics:

High early strength
High performance
Shorter construction time

Both the government and the industry have demanded improved concrete quality. In response to this challenge, concrete technologists/researchers have focused their attentions on:

Changing the properties of the basic ingredients of concrete
Developing new ingredients called admixtures

The ratio of water to cement in the concrete mix design is one of the significant parameters that affect the strength of the concrete. Researchers have found that adding admixtures reduces the water-cement ratio in the concrete mix, which, in turn, results in higher-strength and more-durable concrete. The development and use of new materials that have cement-like properties to replace or supplement cement has significantly improved the durability of concrete. Some of these materials are fly ash, silica fumes, and slag. These materials, when added to the concrete mix design, reduce the permeability of the concrete, thus increasing its durability.

Today, concrete technologists face numerous difficulties that need to be addressed. On one hand, designing high-performance and high-strength concrete requires newly developed admixture, and on the other hand, it has been observed that, due to the same admixture, the concrete undergoes excessive shrinkage and cracking. Thus, the very purpose of using such mixtures is defeated. Another burning issue facing concrete technologists is related to curing concrete. What should be the timing, duration, and type of curing? What should be the balance between the curing time and the speed of the construction? These are some of the questions that need further research in order to be answered.

Another problem facing the concrete industry is that of producing "Green Concrete." In the field of science and engineering, the concern over global warming and ecological changes is growing. The concrete industry's contribution to these environmental changes has been significant. Just consider the fact that in order to produce one ton of Portland cement, it requires up to 7000 MJ of energy, and it produces around one ton of carbon dioxide. These adverse impacts on the environment have forced the concrete industry to identify environmentally friendly practices and processes.

Still another challenge faced by the concrete industry is the "knowledge gap." Research and development carried out at research institutes need to be disseminated to the practitioners for implementation. An effective training program would be very effective in bridging the knowledge gap. Some of the topics that could be useful in such a training program are:

The properties of individual concrete ingredients
Interactions of various ingredients in concrete mixtures
Arriving at the optimum mixture for different types of applications
Desired level of exposure to adverse environments

Another challenge faced by the concrete industry is the need to evolve the advanced methods of testing concrete and its ingredients. Some of the current testing methods are simple but time consuming. The pace of construction cannot be compromised for slow testing methods and, therefore, new or improved tests need to be developed. These test methods should combine speed, accuracy, and precision. New, non-intrusive devices and other tests should be devised to combine speed, accuracy, and precision.

In brief, it can be summarized that the concrete industry needs researchers/concrete technologists who can carry out well-planned basic research. These research programs should focus on promoting and developing comprehensive understanding of the properties of concrete and its ingredients. Also, new and improved methods of testing concrete and its ingredients should be evolved. And finally, the knowledge and methods acquired in lab research should be transferred to concrete practitioners for implementation.

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Concrete Technology: Challenges