The Long Road to Today's Portland Cement

 

Ancient History:

Cement has been in use by humans throughout history; variations of the material were used up to 12,000 years ago, with the earliest archaeological discovery of consolidated whitewashed floor made from burned limestone and clay found in modern-day Turkey. 

The first fired clay bricks were developed in the so-called Fertile Crescent, where it was discovered that lime could be produced from burnt limestone to prepare mortar. Around 800BC, the Phoenicians used the knowledge that a mixture of burnt lime and volcanic ash, today called 'pozzolana', could be used to produce hydraulic lime, that was not only stronger than anything previously used, but also hardened under water.

The Romans developed new masonry techniques, with which they could erect grand buildings with heavy foundations. One such development was "opus caementitium", a type of concrete made of lime with aggregates of sand and crushed rock. This was mostly used between masonry stones or bricks, serving as formwork. Other cements used crushed brick, tiles and ceramic pottery as aggregates. The Roman architect and engineer Marcus Vitruvius Polllio comprehensively described the knowledge and construction techniques of the time, which went on to to serve as the basis of building methods for hundreds of years.  

Famous historical buildings made from concrete, still standing today, are the Colosseum and Pantheon in Rome, and the Hagia Sophia in Istanbul.

The Middle Ages

The Middle Ages were a quiet time in the history of cement; any discoveries made during this era remain unknown, although masons are known to have used hydraulic cements to build structures such as fortresses and canals.

In the guilds of the Middle Ages, knowledge was a secret and was pased on to students orally, not written down, whilst alchemists researched properties and reactivity of substances, often using coded language. Typical mortars from this time consisted of lime and sand - concrete as we know it did not yet exist. 

The Industrial Revolution in Europe in the late 18^th century saw a flurry of new developments in cement and concrete, with important contributions made by John Smeaton, who discovered that the hydraulicity of lime was directly related to the limestone’s clay content, James Parker, Louis Vicat and Egor Cheliev.

The Birth of Portland Cement:

The precursor to modern-day cement was created in 1824 by Joseph Aspdin, a British bricklayer and builder, who experimented with heating limestone and clay until the mixture calcined, grinding it and then mixing it with water. Aspdin named this Portland Cement, after the famously strong building stone from the Isle of Portland in Dorset, UK. His son, William Aspdin, made the first cement containing alite (an impure form of tricalcium silicate).

In 1845, Isaac Johnson fired chalk and clay at much higher temperatures than the Aspdins, at around 1400-1500^oC, which led to the mixture clinkering, and produced what is essentially modern-day cement.

From 1850, the use of concrete made from Portland cement increased considerably. Projects such as sculptures, small bridges and concrete pipes were typical applications at the time and helped to increase its prominence. Then followed large scale sewage systems, such as in London and Paris, and the construction of metros and subways boosted demand. By the end of the 19th century, hollow concrete blocks for housing construction became mainstream. 

The advent of reinforced concretes began in the 1840s in France, starting a period of innovation, using reinforced columns, girders and so on to allow the construction of larger bridges, taller and larger buildings etc, and significantly decreased the dominance of steel construction. 

The first cement standard for Portland cement was approved in Germany in 1878, defining the first test methods and minimum properties, with many other countries following suit. 

Cement production and applications surged globally at the turn of the century. Since the 1900s, rotary kilns replaced the original vertical shaft kilns, as they use radiative heat transfer, more efficient at higher temperatures. achieving a uniform clinkering temperature and produces stronger cement. Gypsum is now also added to the resulting mixture to control setting and ball mills are used to grind clinker.

Other developments in the last century include calcium aluminate cements for better sulphate resistance, the blending of Rosendale (a natural hydraulic cement produced in New York) and Portland cements to make a durable and fast-setting cement in the USA, and the increased usage of cementitious materials to store nuclear waste.

The Future of Cement and Concrete

New technologies and innovations are constantly emerging to improve the sustainability, strength and applications of cement and concrete. Some advanced products incorporate fibres and special aggregates to create roof tiles and countertops, for example, whilst offsite manufacture is also gaining prominence with the rise of digitalisation and AI, which could reduce waste and improve efficiency and on-site working conditions. Cements and concretes are also being developed which can absorb CO₂ over their lifetimes, reducing the carbon footprint of the building material.

 

Text contributions by Rainer Nobis, author of "Illustrated History of Cement and Concrete", available to buy online.

WCA established the Professional Committees and Networks to deliver practical value; action on sustainability; actionable workplans and knowledge sharing forums for the Association’s members.

Committees: The Committees are responsible for investigating member needs; raising awareness of important issues in their area of focus; delivering an agreed action work plan; and play a key role in organising related events such as member forums and working towards a "Net Zero, Zero Harm" cement industry. All committees are particularly careful to observe the requirements of anti-trust rules and to focus on legitimate areas of common concern. Where necessary, participation in events by direct competitors is restricted.

Networks: The networks provide a point of liaison on the Committee topics with member companies, feeding back on initiatives, actions and points of interest, as well as providing a discussuion forum for professionals across the global industry. There are 2 networks within WCA - these are the Committees Network and the Women in Cement and Concrete Coalition (WCCC.) Please note the GFN operates outside of the Professional Committee/Network structure - you can visit the Network's page here. 

 

Zero Carbon & Environment Committee:

The Environment and Climate Change Committee focuses on the industry response to climate change and other environmental challenges such as biodiversity and water management. It also enhances members’ opportunities to learn about new environmental technology and stimulates sharing of best practices that promote sustainable development in the worldwide cement industry. In addition, the committee monitors environmental developments in other industries that may be relevant to cement.

Product, Materials & Concrete Committee:

The Product, Materials and Concrete Committee’s key aim is to support WCA’s members in areas such as new products, concrete, and cementitious/material technologies, their applications, particularly those that have the potential to contribute to decarbonisation. 

Operations & Performance Committee:

The Operations and Performance Committee’s key aim is to support WCA’s members within, and provide oversight for, the PEGASUS project and associated plant audits, and encourages members’ innovation in this area by sharing best practices, including the improvement of both supply chain efficiency and environmental performance.

22-24 July 2020
London

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WCA is the original international cement association, founded in 2016 with the aim of representing the interests of the whole industry. Our corporate members are cement producers and of all sizes, from the world’s largest cement group to companies with a single plant. Our associate members represent the wider cement ecosystem including suppliers of technology, services and equipment.

Our focus is on emerging economies, since almost all of the future growth will be in these countries. Furthermore, it will be companies from emerging economies that will shape the future of the industry. At the same time, we recognise the contribution that companies from developed countries will continue to make in addressing the industry’s technical and sustainability challenges and warmly welcome them to become members.

Climate change is one of the preeminent issues of our time, but the world is still far from being on track to achieve the objectives of the Paris Agreement. WCA supports a sustainable cement industry and encourages technical development and other steps to achieve full decarbonisation.