The UK Cement Admixture Association
September 19, 2005

Admixtures are well accepted and recognised as an important component of concrete, essential for many current construction designs and placing methods. However 40 years ago admixtures were regarded with great suspicion by many engineers and their use was frequently excluded in the specification. It was against this background that the UK Cement Admixtures Association (CAA) was formed in 1963. The members included all the major admixture manufacturers and some associated companies including raw material suppliers and dispenser manufacturers.

The initial goal of the association was to educate the industry in the benefits that could be obtained from admixture use and provide good technical information on the way they worked, as well as the short and long term effects they imparted to the mechanical properties of the concrete. To achieve this goal the association members co-operated to form a team of technical experts who could give seminars which dealt with all aspects of admixture use and specifically addresses the concerns of engineers.

As part of this effort, in the late 1960s, the CAA initiated the drafting of British Standards BS5075 parts 1, 2 and 3 for plasticising, air entraining and superplasticising admixtures. These were followed by BS4887 parts 1 and 2 for mortar plasticisers and mortar retarders. The standards set minimum requirements of performance that each admixture type would give to a concrete mix but also required that the supplier provided information on the admixture as supplied that could be checked at the time of delivery to prove uniform quality of supply.

The programme of education continued through the 1970s but by 1980 the emphasis of the CAA was placed on quality, and the association founded its own quality scheme, which became a qualification for membership. This had the effect of reducing the numbers of full CAA members, as only those committed to high industry standards remained. The CAA Quality Scheme eventually became the basis for the ISO 9000 Quality System for admixtures with fully independent third party auditing.

These CAA initiatives removed most of the engineers concerns over admixtures and there was a steady growth in their use. However, design of concrete structures, methods of placing and issues of durability were only just starting to change. Most concrete was still specified at 50mm slump with the durability advantages of higher workability and low water cement ration being of little concern for all but the most demanding applications. As a result, admixtures were still not used in the majority of the concrete. This has now changed. Durability and sustainability are of major importance for 21st century construction and designs are much more demanding on the fresh and hardened properties of the concrete. These are all requirements that can be most effectively met by the use of admixtures and the latest statistics produced by the CAA suggest that at least 75% of all ready-mixed and precast concrete now contains an admixture.

During the last decade CAA activity has been dominated by the drafting of the European admixture standards EN480 and EN934, which have now replaced BS5075 and BS 4887. To achieve European admixture industry consensus on the content and requirements of the standards the CAA became and instigator and founding member of EFCA; the European Federation of Concrete Admixture Associations and since then has generally provided its secretarial function.

As legislation on construction has shifted to the European Union and Brussels, the CAA activity has also become increasingly dominated by working with EFCA and the CAA remains one of its most active members. As well as the European product standards, EFCA is also heavily involved with the committees developing the European Acceptance Scheme (EAS) for Drinking Water and on the legislation on release of Regulated Dangerous Substances in relation to construction products. Although there is no evidence that concrete or admixtures are a problem in these respects, the industry must be well represented on these committees in order to provide good information and support to the drafting of the new regulations.

European activity has also resulted in EFCA and CAA becoming more involved with related concrete associations in Europe as well as the UK. These associations co-operate through the concrete platform whos membership include CEMBUREAU (BCA in UK), ERMCO (QPA in UK) and BIBM (BPCF in the UK). As well as working together on European legislation and standards, the co-operation also covers technical information such as production of the European Guidelines on the specification and use of self-compacting concrete. There is also work on environmental and sustainability issues with Environmental Product Declarations (EPDs) and LCA information now available on concrete and its components including admixtures.

In the UK, the CAA works with the Concrete Society in production of technical reports including recent issues on Industrial flooring, self compacting concrete and TR 18 on admixtures. CAA is also involved on the materials, environmental and sustainability groups.

The CAA continues to represent all the main UK producers of admixtures and has become well respected in the concrete industry as the focus for quality, for technical information and for support from the admixture industry.

Archive News