The Enquirer has been shown official figures which highlight the full extent of current import levels.
The numbers come as fears continue to grow over the quality of some Chinese rebar which has failed to comply with British Safety standards.
The Enquirer revealed earlier this week that major contractors are now refusing to use Chinese rebar on new projects.
But millions of tonnes of imported material have been used on projects since the start of this year.
Figures show that 184,000 tonnes of rebar have been imported into the UK from China in 2014 out of a total market volume of 442,000 tonnes.
One industry expert said: “I think a lot of people will be stunned by the scale of imports.
“There’s been a perception that this is a problem for smaller sites but that’s not the case.
“Chinese rebar has been used on some of the biggest projects in the country.”
Stephen Elliott, chairman of the British Association of Reinforcement said: “In addition to the issue of quality and non-compliance to British Standards, the fact that 1 in every 2.5 tonnes of steel rebar is imported from China has significant implications for those clients and main contractors who have declared green construction agendas.
“Chinese rebar is not covered by any UK recognised rebar sustainability scheme. Chinese rebar has no proven responsibly sourced credentials.
“For assured quality and proven sustainable sourcing BAR fabricators members are recommended to source from UK and European suppliers.
“It is a recommendation that we also make to clients, designers and contractors.”
Ian Rodgers, director of UK Steel said: “This quantity of rebar flooding the market in such a short period of time – prior to last year the Chinese had never sold rebar here before – is immensely disruptive.
“It threatens the livelihood of steelworkers across Europe.
“We have been in dialogue with both the British government and European Commission about this, and both are supportive of the need to find a legal solution to the problem.
“In the meantime, we continue to be concerned that an unknown proportion of the Chinese material is verifiably sub-standard.
“And with this enormous quantity of Chinese rebar in the market, the risks to contractors are magnified.”