It is the role of the steel mill metallurgist and subsequently the reinforcement fabricator to ensure that the property requirements are met.

Methods of manufacture: Whilst oxygen and electric arc steelmaking remain the most prevalent processes of steel manufacture, there is however another route used in many parts of the world, including Europe - by re-rolling finished products (for example, sheet or rails) - although it is not permitted in most product standards.

The main sources of this raw material are permanent way rails and railway axles that have reached the end of their service and demolition scrap, generally arising from ships.

In North America, ASTM standards deal with the first two sources and both contain a requirement that the bars are identified appropriately. In Europe, there are no provisions in product standards for the use of re-rolling scrap materials. This does not prevent small manufacturing units coming into operation to provide such reinforcing steels, it is hoped, for non-critical applications.

The major disadvantages of this production route are:

An examination of the supply of reinforcing steels to the UK prior to the operation of Cares has shown:

Because of such problems, the UK Certification Authority for Reinforcing Steels was established and the Cares Scheme was developed. It is based on three components: ISO 9000 quality systems; Cares quality and operations assessment schedules; and extensive product sampling and testing.

ISO 9001: While requirements of this internationally-accepted model for quality management systems are well-known, it is clear however that the history of the standard and the certification process associated with it illustrate strongly that, to ensure confidence in continued product compliance, its requirements must be applied by both manufacturer and certification body according to the product and industry in which it is being used.

Cares quality and operations assessment schedules: It is essential to identify, for each sector and for each industry, certain critical areas of production processing that require assessment in depth. This is particularly true for product conformity certification, where assurance must be provided for both the quality management and the manufacturing techniques.

There is of course an assessment schedule for the production of hot-rolled bar and coil, the material form supplied to downstream processors in Dubai. There is also an assessment schedule for cutting and bending but, whilst Cares has had expressions of interest from firms such as Corporate Technologies in Dubai, to date this important area of the supply chain is not covered, unlike the UK where almost all cutting and bending is done under certificated conditions. This will hopefully be corrected in Dubai in the future.

Additional schedules continue to be developed for other products connected with steel for concrete reinforcement including welded reinforcement prefabrications, epoxy coated rebar and mechanical splices.

Product sampling and testing: Where activities influencing the specified properties of the steel are carried out, product conformity assessment is applied in three interlocking stages: review of suppliers test records; witness testing of samples selected by the assessor; and duplicate testing of the latter by an independent test house.

The statistical basis of sampling for bar and coil is as follows:

(m = mean, Cv = Characteristic value, k = acceptibility index, S = standard deviation of population);

In addition, the magnitude of the standard deviation of results from the 10 samples from each cast is examined for "within cast" variability to determine the degree of process control.

Following a satisfactory assessment covering the three main areas, a certificate of approval is issued stating the name of the company, the factories to which the successful assessment applies and the products covered. The approval is based on the manufacturer's production and process route which is held in the Certification Authority's records. No changes to this are permitted without authorisation.

Following approval, surveillance inspections covering all the aspects of the initial assessment are carried out at least twice annually. On procedural matters, the inspection is on a sample basis but it is treated so that any weaknesses are re-examined subsequently. After a number of surveillances, the entire system is re-assessed.

Emphasis is placed, in all assessment schedules, on the control of processes that influence the conformity of the material with the product standard. Traceability is of major importance because of the complicated commercial route from steelmaking to the construction site.

Figure 1 shows an overview of the material flow in the reinforcing steel industry. Billets are cast in typical weights of 100 tonnes. For reasons of economies of scale rolling programmes may extend to thousands of tonnes. Distribution to traders and stockholders could, in cast terms, be as small as 10 tonnes with the distribution to contractors, again in cast terms, sometimes in fractions of a tonne.

Whilst the product itself may therefore seem simple in form, the large production quantities at the steel mill, followed by significant dispersal throughout the supply chain, illustrates the need for a robust, yet simple system of traceability.

Reinforcing steel is produced in units known as "casts" which refers to the quantity of molten steel cast into billets for further rolling into bar or coil. The chemical analysis of the steel is controlled within the melting process. This, in turn, affects the material's response to further processing (that is, rolling into bars, which therefore dictates the mechanical properties). As the chemistry and therefore the resultant mechanical properties are cast-dependent, it is therefore important to retain traceability to cast throughout the supply chain so that problems - should they arise - be traced and acted upon as appropriate. Each cast is given a unique number which, along with the associated chemistry and mechanical and dimensional properties, is documented on a certificate of test produced by the steel mill.

Material: All reinforcing steel bars in either straight lengths or in coil form, produced to BS4449 and BS4482, must include a rolled-on mark which, for Cares-approved firms, takes the form of dots between the transverse ribs on the bars (Figure 2). These marks, by use of specific combinations of dots and ribs, indicate:

The product standard requires that these marks must appear at distances along the bar of not greater than 1.2 m.

Associated documentation: Steel bars or coils are sold into the market in coil or bundle typically weighing two tonnes. Cares requires that these are accompanied by a label, indicating the cast number as well as the Cares logo and certificate number of the mill. Each cast delivered in whole or in part to a reinforcement stockist or fabricator, must be accompanied by a certificate of test. Cares requires that this certificate is endorsed with the Cares logo, the unique certification number of the manufacturer and a reproduction of the rolled-on mill mark used by the steel mill, as well as the cast number.

These manufacturers and their unique certification numbers and mill markings are published in a register of approved firms which is regularly updated and widely circulated throughout the construction industry in hard copy as well as on the Cares website. By purchasing material from those steel mills in the register, all stockists and fabricators, and their subsequent contractor clients, have the ability to control their stocking and processing, either in-house or on-site, to enable traceability of the steel as cast into concrete.