Imported Dutch precast concrete structural interlocking blocks containing high lead content recycled glass aggregate could be reclassified as hazardous waste, NCE has learned.
The suspect blocks have been coming into the UK for at least three years, but the Environment Agency has stated that the producer has so far failed to provide evidence that it complies with environmental protection regulations, particularly the “End of Waste” test.
This requires the producer to demonstrate that the “processed substance” can be used in exactly the same way as a non-waste, and can be stored and used with no worse environmental effects.
“We continue to request information, but are now acting in its absence,” the Agency told NCE last week.
Representatives from producer Jansen are set to make a last ditch attempt this week to convince the Agency that there has been no breach of the regulations.
Reclassifying the giant Legioblocks, which are dry-stacked to form retaining walls, storage bays and firewalls, would have serious implications for those who have purchased them in good faith.
Current legislation would require each location to be licensed as a waste disposal site, while any company transporting the blocks from east coast ports would also need to be licensed.
More complications would arise from Jansen’s claim that only 20% of the “many thousands” of blocks supplied contain the high lead content glass.
Unless Jansen’s records can pinpoint where the suspect blocks were delivered, customers may have to carry out tests to discover if their blocks contain the controversial aggregate.
The risk is that any lead in the blocks will leach out into the environment over time. Lead is now known to be a potent neurotoxin causing brain damage and blood disorders.
The glass comes from old cathode ray tubes (CRT), much of which is exported from the UK to Jansen before returning as aggregate in the Legioblocks. Jansen has confirmed that it processes the CRT glass only to remove the fluorescent chemicals on the screen (See box).
Jansen told NCE: “ A mixed fraction of CRT glass containing both leaded (30%) and unleaded (70%) glass is used as an aggregate in Legioblocks. Fluorescent powders (phosphors) are extracted by a mechanical treatment process.”
UK precasters and waste disposal companies have been jointly lobbying the EA for more than 18 months, claiming that Jansen was undercutting them by 40% or even more by using the CRT waste in their products. There was outrage recently when Natural Resources Wales (NRW) renewed a license for the export of up to 10,000t of CRT waste to Jansen.
Industry trade association British Precast executive director Andrew Minson said that UK producers of structural precast concrete had to use aggregates conforming to BS EN 12620. He added: “UK producers have to use quality aggregates, so do European producers..
“And no-one should put hazardous waste into concrete as it could compromise the use of all crushed concrete in the future.”
Minson said there was potential confusion caused by the catch-all appellation “concrete blocks” being applied to structural interlocking units. “These Legioblocks measure 1600mm x 800mm x 800mm and weigh more than 2t each. They bear no resemblance to the small concrete masonry units we’re all familiar with.
“Large interlocking blocks should use aggregates complying with BS EN 1260.”
UK interlocking block producer Elite Precast Concrete sales and marketing director Owen Batham told NCE he was first made aware of possible problems with the Jansen blocks nearly two years ago. “I had a call from someone who had purchased a load of Legioblocks which he said were falling apart.
“I visited the site, and they did look awful, so I arranged for cores to be taken and independently tested”.
Made available to NCE, the test report from Kiwa CMT Testing of Derby is unambiguous. The concrete was found to contain “unprocessed crushed CRT glass as fine and coarse aggregate, wire, various plastics, fibrous materials such as insulation, friable materials etcetera.”
Chemical analysis showed “significantly high lead content which would be classified as hazardous waste”. Density was “very low”, excess voidage “high” and compressive strength “very poor” at only 10.5N/mm2.
There was also the risk of alkali-silica reaction (ASR), as there was a significant amount of CRT glass present, whose soluble silica content is unknown.
The report concluded that the block tested was “a poor quality and potentially dangerous product,” and that “It would appear that Hazardous Waste is being used to produce a Hazardous Product that will at some point become Hazardous Waste again.”
In response to a question from NCE as to why there had apparently been no further tests on the suspect units, the Agency stated: “We have approached both the manufacturer and the complainants to request more information… but to date neither has been willing to provide it.
“We have not commissioned our own testing due to the significant costs involved.
Kiwa CMT told NCE that a single core test for compressive strength and lead content would cost around £200, while a full investigation involving cores cut from a number of blocks at different locations could be done for around £5,000.
At least two UK companies that have invested heavily in facilities to extract the lead from CRT waste by either chemical treatment or in a special furnace are struggling to survive.
Waste treatment company SWEEEP Kuusakoski managing director Patrick Watts said: “We have invested millions in developing furnaces which can treat CRT waste responsibly.
“We can recover 2t of 99% pure lead a day, and produce a range of high quality aggregates from the purified glass. It’s an expensive process, but it’s still cheaper than landfill. But we can’t compete with people who don’t extract the lead and just tip the waste into concrete moulds.”
SWEEP has now shut down its furnace, he confirmed, pending a positive decision from the EA.
Jansen also confirmed that it plans to start production of Legioblocks in the UK. It said: “Due to high transportation costs Jansen will start manufacturing in the UK in the short term. Since the UK site does not have any waste treatment facilities no glass aggregate will be used.”
Cathode Ray Tube technology an ever present
Although Cathode Ray Tube (CRT) technology is now being replaced by flat screen technology there are still millions of CRTs in use worldwide, in TVs and computer monitors, arcade games, cash machines and oscilloscopes. Some 90,000t of electronic waste containing 20,000t of high lead content glass has to be disposed of in the UK every year. CRT glass from old CRTs used to be recycled into new CRTs: with this end use in decline other means of dealing with the potentially toxic waste had to be devised.
A typical colour CRT is made up from a neck section containing around 40% lead oxide and a funnel section containing about 20%, soldered to a screen virtually free of lead. It does, however, contain barium, strontium and zirconium oxides.
The solder used has a lead oxide content up to 90%. Coating the inside of the screen is a mixture of fluorescent chemicals, typically zinc, cadmium and yttrium sulphides.
An Environment Agency guidance document issued in October 2011 stated that treatment of the CRT glass must involve the removal of the fluorescent coating, and should prioritise either recycling into new CRTs or the recovery of lead from the glass. It said that a position statement confirming the waste controls on the use of CRT glass would be published after January 2012.