The Ministry of Construction (MoC) is currently evaluating the feasibility of combining thermal power ash and clinker with saline sediment to service coastal road projects.

Thermal power ash and slag still underutilised, illustration photo/ Source: freepik.com

If approved, the move will bring two significant benefits: the elimination of industrial refuse and the alleviation of difficulties in supplying materials, which is one of the primary factors delaying several transport infrastructure projects, according to Tran Phuoc Loi, deputy director of Thuan Hoa TV Company, a firm providing backfilling services for construction projects.

“Ash and slag do not have an opportunity to compete, since when developing design documents, most contractors see sand as the only solution,” Loi said.

Multiple Thuan Hoa TV projects in 2022 indicate that the quality of levelling ground made from ash and slag is comparable to that of sand. The price of one cubic metre of thermal power ash and slag is equivalent to two-thirds the price of one cubic metre of sand, but transportation costs are higher.

Nguyen Van Sinh, Deputy Minister of the MoC, said last month at a workshop, “The MoC will soon propose remedies to overcome the lack of levelling materials for transport infrastructure projects in the Mekong Delta region, particularly the North-South Highway project’s phase 2.”

Last month, the government proposed to the National Assembly that the time limit for implementing the tailored mechanism for exploiting minerals for common construction materials be extended until the end of 2024 because the majority of projects in the Mekong Delta region face difficulties in sourcing materials, particularly sand for foundations. In a March report, the MoC stated thermal power plants are attempting to use ash and slag as infill material in infrastructure projects, but only use half of that available. Vietnam’s coal-fired power facilities released an estimated 16 million tonnes of ash and slag in 2022, of which only 48 per cent was utilised.

The ministry believes that emissions of ash and slag from 29 thermal power plants in operation in Vietnam will continue to rise in the future, from approximately 16 million tonnes in 2022 to 20 million tonnes in 2025. Vietnam Electricity is unlikely to meet its 2023 goal of completely consuming 10 million tonnes of ash and slag, it has said.

As of August, the national backlog of thermal power ash and slag was approximately 48 million tonnes. Using ash and slag as an infill material is not economically and technically attractive, and many factories lack capacity to process and classify it, leading to sluggish consumption.

For example, Vinh Tan 4 thermal power plant in the south central province of Binh Thuan has an extremely sluggish consumption rate, at 1.47 million tonnes in total

“Construction companies are wary and believe ash and slag are novel materials, so they cannot use them for infill without risk,” said Pham Dinh Quang, deputy director of Vinh Tan 4.

The company has offered financial opportunities to customers, but to date has only signed contracts for consumption with two companies.