Directive 08/CT-TTg of the Prime Minister was issued in 2021 to promote the treatment and use of ash, slag, and gypsum from thermal power, chemicals, and fertilizers plants as raw materials for construction materials production and construction work. This is an important document, guiding most thermal power ash and slag treatment activities.
Abundant supply
The Ministry of Construction said that according to summary data from Vietnam Electricity (EVN), Vietnam Oil and Gas Group (PVN), Vietnam National Coal and Mineral Industries Group (TKV), the whole country currently has 31 Coal-fired thermal power plants in operation. In 2023, the total amount of ash and slag from thermal power plants nationwide will be more than 18.07 million tons.
Ash and slag landfill of Duyen Hai Thermal Power Company
The treatment and consumption of ash and slag from thermal power plants across the country have tended to increase gradually in recent years, gradually approaching emission levels. In 2023 alone, the amount of ash and slag consumed nationwide will reach more than 18.01 million tons - equivalent to 99.6% of the total emissions for the year.
By the end of 2023, the total amount of thermal power ash and slag consumed cumulatively over the years across the country is about 83 million tons - accounting for 66.2% of total emissions so far. The total volume of ash and slag currently stored at the landfill of thermal power plants is 46.4 million tons.
Research to level construction works and build roadbed
Mr. Ngo Van Sy, Director of Duyen Hai Thermal Power Company (Tra Vinh province), informed that 3 thermal power plants of Duyen Hai 1, Duyen Hai 3, and Duyen Hai 3 expansion are having difficulty in consuming ash and slag stored at the landfill. Every year, Duyen Hai Thermal Power Company's ash and slag landfill is sampled for testing and granted a certificate of compliance according to current standards and regulations by the Institute of Construction Science and Technology - Ministry of Construction. Specifically, the certificate of ash and slag compliance meetsTCVN 12249:2018 - coal thermal power ash and slag as leveling material; Certification of fly ash compliance for concrete, mortar, and cement in compliance with QCVN 16:2017/BXD. Specifically, the certificate of ash and slag compliance meetsTCVN 12249:2018 - coal thermal power ash and slag as leveling material; Certification of fly ash compliance for concrete, mortar, and cement in compliance with QCVN 16:2017/BXD.
Referring to the solution to the problem of storing millions of tons of ash and slag, Duyen Hai Thermal Power Company said it will develop documents to invite processing and consumption. The company will widely release solicitation documents to attract potential ash and slag consumers.
Thermal power ash and slag used to make unburnt bricks
According to Mr. Le Van Han, Chairman of the People's Committee of Tra Vinh province, the province is conducting research on the "Application of technological solutions using a combination of ash, slag of Duyen Hai Thermal Power Plant and saline sand as materials for roadbed and cement concrete for road surfaces, in order to contribute to the effective use of existing raw materials in the area to serve traffic works in Tra Vinh and the Mekong Delta".
This study will evaluate the quality and durability of ash and slag when combined with saline sand on a 100 m test road with 54 measurement locations. Authorities will consider the economic-technical efficiency and environmental impact of the combined use of these two materials.
Recently, during a working session between Prime Minister Pham Minh Chinh and leaders of provinces and cities in the Mekong Delta, Mr. Nguyen Van Hieu - Secretary of the Can Tho City Party Committee - proposed that localities be allowed to use thermal power ash and slag as leveling material for traffic road and industrial park infrastructure.
According to statistics, from now until 2026-2027, Can Tho needs 20 million m3 of sand to build key traffic projects, industrial parks, commercial and service areas, etc. However, the city does not have a large sand mine so it cannot be exploited to serve these projects.
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Research and evaluate when thermal power ash and slag used as a highway
According to the group of authors who compiled the national standard TCVN 12660:2019 on "Ash and slag from coal-fired thermal power plants for car road bed- Technical requirements, construction, and acceptance", this material has not been applied to level roadbed for highway, can only be used for roads of level IV and below.
Because thermal power ash and slag with small particle sizes (0.01 - 0.1 mm, belonging to the dusty soil group) are inert and less sticky. Therefore, roadbeds made of ash and slag can easily become unstable when subjected to large loads (heavy vehicles and the number of vehicles is as large as the highway). In areas with high groundwater levels, roadbeds using ash and slag can easily liquefy, lose strength, and lead to damage.
"Thus, the use of thermal power ash and slag in highway construction needs to be further researched and evaluated. However, in the immediate future, thermal power ash and slag can be used in the construction of concrete structures, concrete bridges, viaduct highways, etc." - Evaluation by the Ministry of Construction.
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