Artificial sand is too expensive
Questioning the Prime Minister, National Assembly delegate Nguyen Huy Thai asked: "One of the solutions that the Government and the Prime Minister have directed to implement in the coming time is: Immediately remove difficulties and obstacles regarding material sources, especially in the Mekong Delta.
According to experts, there is an alternative solution to natural sand, which is artificial sand. So, will the Government consider this solution? Is it feasible to apply this solution in the Mekong Delta?
Regarding this issue, the Prime Minister said that currently, the demand for materials used for filling and embankment for transport projects in the Mekong Delta region is very large, with the four key expressway projects currently being implemented requiring about 56 million m3 , not to mention the demand for sand materials for embankment for other projects invested by local authorities.
Prime Minister Pham Minh Chinh shared his concerns about solving traffic infrastructure in the Mekong Delta during the 6th session of the 15th National Assembly (Photo: VGP/Nhat Bac).
The solution of using artificial sand to replace natural sand for traffic construction projects has been used by the transport sector for many years in areas lacking natural sand resources. In particular, the Mekong Delta is the area that mainly uses sand as a roadbed material with a very large demand.
If using artificial sand to completely replace natural sand, it is necessary to exploit very large quarries as well as arrange many new production lines to meet the demand and the cost is much higher than natural sand.
Why can't we increase river sand mining capacity?
Although the reserves of river sand materials have been identified by localities and basically arranged enough resources, the exploitation and supply capacity has not met the material demand according to the progress of project implementation.
Excessive exploitation capacity will lead to riverbank erosion, affecting social life in the area. In addition, the Mekong Delta is an area greatly affected by climate change.
Therefore, to solve the shortage of construction sand materials for projects in the Mekong Delta region, the Prime Minister has directed the Ministries of Transport, Construction, Natural Resources and Environment, and Science and Technology to focus on researching solutions to apply alternative materials nationwide in general and in the Mekong Delta region in particular.
Therefore, the Prime Minister said: "Applying this solution to completely replace natural sand in the Mekong Delta region is not feasible, so priority should only be given to replacing natural sand in some items with small usage volume such as: production of asphalt concrete, cement concrete..."
To ensure timely supply of sand for construction projects in the Mekong Delta, the Ministry of Transport has implemented a pilot project to use sea sand instead of river sand, organized monitoring and surveillance, and established a ministerial-level council to evaluate the pilot results.
The pilot results show that sea sand in Tra Vinh province meets the technical requirements for making automobile roadbeds. Sea sand/salty sand can be used to build automobile roadbeds for the lower roadbed area (K95) under saline conditions similar to the pilot area.
However, the pilot project has only been implemented on a small scale, the design scale is lower than that of the highway, the quality of beach sand has only been studied for one area, and the standards and regulations on salinity for crops and livestock are not complete.
Therefore, the widespread use of sea sand materials for road construction needs to be further piloted and expanded in projects with higher scale and design levels as well as piloted in different natural and environmental conditions for comprehensive evaluation.
The current sand-filling trial construction section is the restoration road of provincial road 978, about 300m long.
At the same time, the Ministry of Natural Resources and Environment has deployed and completed part of the project "Mineral resources assessment, serving sand exploitation, meeting the needs of filling highway projects and urban and traffic infrastructure in the Mekong Delta region".
The project has evaluated the quality of sea sand minerals in the 0-10 m water sea area of Soc Trang province (area B1, area 250km2 ) to have quality that meets the requirements for roadbed filling materials according to regulations.
At the same time, the Ministry assessed the mineral resources of sea sand for construction materials level 333 + level 222 at 680 million m3 , level 222 resources are 145 million m3 , area B1 is eligible for immediate transfer to the mining unit.
The Ministry of Natural Resources and Environment has transferred the Project results to the People's Committee of Soc Trang province and the Ministry of Transport. Currently, the Ministry of Transport is coordinating with the People's Committee of Soc Trang province to implement exploitation procedures to serve the pilot expansion construction.
The solution of building a viaduct requires a large amount of funding.
Regarding the research on building expressways on viaducts in the Mekong Delta region instead of building expressways directly on weak ground, the Government and Prime Minister have also directed the Ministry of Transport to request consultants and relevant agencies to seriously and comprehensively study the technical, economic, social and environmental aspects right from the investment preparation stage for comparison.
From there, decisions can be made such as using a viaduct for the entire route; extending the bridge over the river to reduce the height of the bridge head; handling subsidence with cement piles, load-reducing floors... to minimize the use of sand for filling, shorten the time waiting for subsidence, increase stability, and minimize risks during construction and exploitation.
However, viaduct construction solutions require large funding sources (currently, the cost of constructing viaducts is about 2.6 times higher than the embankment solution).
In the context of limited investment resources, the sand material source in the Mekong Delta region is still capable of meeting the needs of the expressways being deployed in the 2021-2025 period, so the main solution is to use sand to fill the foundation; treat the bridgehead embankment with cement-soil piles and load-reducing floors; build viaducts for sections with large weak soil depth, ensuring environmental criteria, flood drainage, etc. and with reasonable investment costs.
To prepare for investment in upcoming projects, the Prime Minister has directed the Ministry of Transport to research and comprehensively report on solutions for developing traffic in the Mekong Delta region and plans for filling materials for project implementation.
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