The potential of additives in cement production

1 Introduction

A transformation has been in progress in the cement industry for some time. This not only means formidable challenges but also new opportunities. On the one hand, cement factories need to become more and more efficient at the same time as reducing their environmental impact. On the other hand, customers are calling for increasingly high-quality, high-performance cement for more and more complex buildings and increasingly durable infrastructure facilities.

Manufacturers therefore face the conflicting tasks of improving throughput, reducing costs, enhancing the performance properties of cement and cutting emissions – of course at the same time as complying with all the relevant regulations and internal quality standards.

2 Challenges

Technological developments and changes in society in general are causing companies to think about the long-term development of cement production. In this context, focus is on the following issues: What fuel mixtures are to be used in future to generate the extremely high temperatures required? Where are the limits for low-clinker cement? What potential is there for CO₂ reduction?

Cement additive suppliers are thinking about the future role and potential of innovative chemicals in cement production and they are investing to a growing extent in research projects in this area.

3 Use of cement additives worldwide

Formerly, the majority of cement manufacturers attempted to optimize their production processes without additives. To a large extent, cement additives were seen as possibilities for correcting inadequate process efficiency or product quality.

Nowadays, cement additives are used at almost all European cement plants and, thanks to the globalization of the cement industry, also to an increasing extent in emerging economies. Cement producers recognize the benefits of adding chemicals to the cement milling process. A holistic approach including both milling itself and the chemical activation of cement constituents in an integrated process would open up new possibilities and significantly roll back the current boundaries.

As one of the technology leaders in concrete technology, Master Builders Solutions is committed to the cement industry and is assisting manufacturers in achieving their objectives with highly effective additives. The MasterCem product family is based on decades of experience with cementitious materials.

4 Benefits of using cement additives

The main benefits are with regard to costs and the environment: manufacturers need less energy for the milling process, which saves costs and reduces CO₂ emissions. In addition, it is easier to integrate cement replacement materials, the capacities of existing cement factories are increased and investments in new plants are therefore reduced – which also represents a considerable saving in terms of cost and environmental impact.

Higher production efficiency boosts capacities: the mills and separators work more efficiently, there is less clogging of the material, and storage and loading become easier. Plants are stopped less frequently, and maintenance cycles are reduced.

Additives also play a key role in product quality. Cement made using a process of this type produces concrete with higher early and final compressive strength values, the rheology is improved, and the additives compensate for the disadvantages of cement replacement materials. As regards environmental benefits, in addition to lower energy consumption as a result of higher efficiency, it may be possible to reduce the amount of clinker – this is produced with a high energy input – which is required. Furthermore, the more efficient use of existing quarries conserves natural resources.

5 Further development of cement additives

Normally, additives are developed and tested in the laboratory using pot mills and other small mills. Although the data obtained gives a certain indication, it is not really representative. The problem is the size of the balls and their distribution within the ball mill. Small balls are lighter, the mechanical force applied to the substance being milled is significantly lower, the temperature is also lower and there is no particle separation.

For this reason, Master Builders Solutions has invested in a pilot mill. This is a 1:10 scale version of a genuine cement ball mill and it offers realistic conditions without the tremendous cost of tests at a real cement factory. Our pilot mill is located at our development centre in Treviso, Italy, and is used mainly for basic research and for the development of new cement additives in the MasterCem range.

Although the mill is not really intended for this purpose it can also be used for specific customer projects following careful planning.

This mill is a key element in the research and development resources of Master Builders Solutions for cement additives. With this pilot mill, cement can be milled and additives dosed under constant process conditions. The particle size distribution is very similar to that obtained with an industrial-scale plant. For example, the effects of additives on energy consumption and the dosage rate can be monitored on a real-time basis. Enough cement can be produced for complete test series covering properties such as strength and rheology.

Besides the pilot mill, other preconditions have been met for the development of innovative cement additives. There is sufficient space for working with the relatively large quantities of raw materials for the production of cement as well as dedicated equipment. In addition to a cement laboratory fully equipped with items such as slag breaker, small mills, low-temperature milling module, PSD laser analyser, ultrasonic screen and x-ray diffractometer, essential factors include the comprehensive know-how and the research and development expertise Master Builders Solutions has gained over the decades, at its research and development centre in Trostberg, regional development facilities and many local customer service laboratories. The activities of Master Builders Solutions are based on a large team of chemists, physicists, mineralogists, geochemists and civil engineers. Within BASF, Master Builders Solutions can also call upon the globally networked know-how of interdisciplinary research teams. The network includes 1900 cooperation arrangements with universities, research institutions, highly promising start-ups and partners in the industry.

6 Future objectives

Especially in view of the growing cost efficiency and environmental compatibility requirements in the construction industry in general and in the cement industry in particular, chemicals will increasingly become an integral part of cement production.

Cooperation between cement additive suppliers and cement producers will help in mastering future challenges. Everyone must work together intensively on the development of the next generation of cement additives. With investment in resources and equipment and with the support of the BASF Group’s excellent global research and development network, a key part can be played in this evolution.

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