AfriSam explains how concrete has evolved and developed over the centuries.

 

Ancient as it may be, concrete remains one of the most popular construction materials, even in today’s society where technology is moving at a very fast pace. With its track-record as one of the most reliable building materials, concrete has evolved into a product with a wide range of applications and one of the most versatile materials. Not only does it make for durable and sustainable structures, but its uses have broadened to cater for the ever-changing construction demands. As a readily available and economical solution to development requirements, rarely can one find any construction project that does not make use of concrete in one form or another, making it the most utilised man-made material in the world.

Over the centuries, concrete has been able to evolve to cater for the advancements in technology. The surge in sophisticated engineering projects has allowed for the emergence of high-technology concretes as solutions to these trends. High-performance concretes with unusually high compressive strengths are now able to cater for more advanced and application-specific requirements. Through the optimisation of constituent materials and the tailoring of mix designs, concrete can be adaptable to its many uses.

Traditional concrete presents a myriad of problems including limited durability and failures under heavy loading, lending itself to ongoing expensive repairs. High-performance concrete can be engineered to minimise these challenges. Pumping technologies have also evolved to make it possible to place concrete into those hard-to-reach places.

In addition, concrete is also the only construction material that can be moulded into any form at room temperature. All other materials such as steel and wood require heating to certain temperatures before being formed.

The role of admixtures
Furthermore, the introduction of chemical and mineral admixtures in modifying the properties of concrete have significantly improved the versatility of concrete. In its fresh state, admixtures play a significant role in improving the properties of concrete in a number of ways, including increasing the slump, adjusting setting times, reducing segregation, improving pump-ability and reducing bleed. Admixtures have allowed for the production of concretes with a high flow-ability, allowing for easy placement, even into the most difficult places without segregation.

Admixtures can also be used to modify and influence the properties of concrete in its hardened state. This includes the ability to accelerate rate of strength gain, increases strength by reducing the water requirement with a subsequent improvement in durability.
 
The developments in the field of admixtures alone have been phenomenal, allowing for these to be carried over into concrete technology. Thus far, this has included the development of air-entraining agents, retarding admixtures, accelerators, waterproofing admixtures and many more, to support advancement in concrete technology.

Self-levelling concrete trends

The introduction of self-levelling concrete has been another development in technology in concrete manufacturing made possible by the use of admixtures. With the increase in the number of complex projects where accessibility is an issue, self-levelling concrete provides a solution. Again, the use of plasticisers has allowed for the production of a more malleable concrete that is flexible enough to flow into confined spaces. This concrete’s smooth consistency, a low viscosity and a high even flow give it its ability to flow through and around confined spaces between reinforcing bars. The product can also be placed with minimal labour and does not require vibration.

Concrete may also be reinforced using fibres such as glass fibres, synthetic fibres and natural fibres. These options each give the concrete different properties and need to be selected based on application. Fibres may also serve to control cracking. Concrete is known for its relatively low-tensile strength and ductility, the inclusion of steel fibres gives concrete its ability to improve on these aspects.

Green concrete trends
Cement and concrete production introduces a number of environmental challenges, such as the high levels of carbon emissions as a result of production, the depletion of fossil fuels reserves and high energy consumption, which have all been linked to climate change. In response to these, concrete production has also evolved to incorporate more environmentally-friendly methods of production through the use of carefully selected raw materials with a low carbon footprint. The industry has been able to offer green alternatives to OPC-based concretes in the form of blended cement concretes that make use of mineral components such as fly-ash, silica fume and slag. These additives not only reduce the carbon footprint, but also offer technical advantages to concretes.  

Creative, aesthetic solutions
Traditionally, concrete has been known as a grey material used simply as a utilitarian medium. Today, concrete uses have evolved to not only serve its functional purposes, but to include enhancing the aesthetics of a structure. Decorative concrete can be incorporated in decorative inlays and to include dyes and textures to give an endless array of options for its uses.

Engineering technology keeps evolving to resolve a lot of the challenges that concrete presents, making it a much-used commodity that will be around for a long time.   

AfriSam (Pty) Ltd
Tel: 011 670 5500
Fax: 011 670 5793
Email: victor.bouguenon@za.afrisam.com
Website: www.afrisam.co.za