When bottles arrive at Tiostone Environmental in Tuen Mun, they are crushed into glass sand which is mixed with fly ash from power plants and some other construction waste products to form bricks.
"There's no heat or fire involved in the whole process," says Dixon Chan, Tiostone's director.
Some companies, including Coca-Cola and Kowloon Dairy, reuse their glass bottles several times before sending them to Tiostone for recycling.
Tiostone, which began operating in 2005, produces between 10,000 and 15,000 square metres of bricks a year, which are mostly used for paving. At present, the company's biggest buyers are government contractors.
Tiostone ecobricks have been put to use in redeveloping Kai Tak, and are often used to pave emergency vehicle access roads.
"They can sustain the load of a fire truck," he says.
As with most green products, ecobricks are more expensive than their non-recycled counterparts, especially those from the mainland.
"You have to compare apples to apples," says Chan. "We are not on the same page as the Chinese bricks. They are low-strength, do not meet the standard and have very bad colour."
Chan says Tiostone has the capacity to process more waste glass, but finding a market willing to pay for the product has proved difficult. He is urging the government to adopt a green procurement programme to ensure all new government developments use ecobricks and other green building materials.
Another challenge the company faces is high premiums for workers' insurance. It's a common issue in the recycling industry, as new technologies and processes make insurers wary.
"It's a very big disadvantage to all recycling businesses in Hong Kong," says Chan.