Samples of imported steel reinforcing bars from China have failed to meet British standards in independent laboratory tests.
Two samples of rebar, believed to have been produced by the Chinese manufacturer Jiangsu Shagang Group and imported to the UK, were tested by independent laboratory Environmental Scientifics Group, under instruction from trade association UK Steel.
Geometrical assessments by the laboratory found that the samples did not comply with the British Standard for rebar, BS4449, because their longitudinal ribs exceeded the maximum height allowed.
Video evidence shared with Construction News last month showed unlabelled, and potentially non-compliant, bundles of imported rebar on the Liverpool docks and in transit on British roads.
The Jiangsu Shagang Group is approved by the UK Certification Authority for Reinforcing Steels. CARES certifies that concrete reinforcing products comply with the required standards and also guarantees full traceability of the materials from steel mill to site, through marking, labelling and documentation requirements.
Bar marks rolled in to the tested samples identified them as having been manufactured by the Jiangsu Shagang Group, which has been contacted for comment by Construction News.
UK Steel director Ian Rodgers said: “Coming on top of the weak link in the CARES traceability regime relating to imported rebar, it is now becoming increasingly clear that there are risks in using non-European rebar.
“We suggest that fabricators and contractors should test any non-EU rebar they have in stock – and particularly Chinese rebar - to ensure that it is fully compliant with the British Standard.”
Reinforcing bars have ribs rolled into them to ensure they bond with concrete. The pattern and size of ribs is specified in BS4449, with longitudinal ribs not allowed to exceed 10 per cent of the diameter of the bar.
The tested bars were 12mm in diameter, meaning the maximum height of the rib should not exceed 1.2mm.
However, geometric tests by the Environmental Scientifics Group found that the maximum height of ribs on the two samples ranged between 1.633mm and 1.890mm.
UK Steel said the samples were obtained from multiple sources of rebar currently on the British market.
CARES chief executive Ben Bowsher told Construction News it was made aware of the issue on 7 August 2014.
He said: “We have been made aware of a possible non-compliance of imported steel by UK Steel and are investigating accordingly. This also related to longitudinal rib height. We will act according to the situation found.”
Mr Bowsher said it was the second notification CARES had received relating to the longitudinal rib height on a particular diameter of bar.
“On [the first] occasion, after using the services of a separate independent laboratory to test longitudinal rib height, amongst a number of other investigations, we concluded that there was no problem and that that particular lot of steel was in full compliance with the British Standard, BS4449.”
Mr Bowsher added that CARES’ methods to reduce the risk of non-compliant steel being used in the UK “are such that we believe that independent checking of reinforcement is not required”.