Regarding the issue of ensuring highway progress, on September 27, the Ministry of Construction organized a scientific workshop on solutions for effective use of construction materials in the construction of traffic infrastructure works, attracting many experts and businesses to attend.

Many consequences if we continue to exploit soil and sand in the Mekong Delta

Deputy Minister of Construction Nguyen Van Sinh said that in September 2021, the Prime Minister approved the Road Network Planning for the 2021 - 2030 period, with a vision to 2050, with the goal of completing the construction of about 5,000 km of expressways by 2030; by 2050, the planned expressway network will include 41 routes, with a total length of more than 9,000 km.

According to Mr. Sinh, traffic infrastructure works in general and expressway works in particular are often constructed with layers of foundation, foundation, and road surface materials. Except for sections passing through mountainous and midland terrains with mixed excavation and filling roadbed structures that can utilize nearby materials, the remaining sections passing through plains often encounter weak ground, requiring solutions to treat the ground, replace the soil, and raise the ground level, etc., resulting in a very large volume of soil and sand materials needed.

For example, in the Mekong Delta region, in the period 2022 - 2025, 4 expressway construction projects will be simultaneously implemented with a demand for about 36 million m³ of sand for embankment.

"With the current solution of using river sand to build roadbeds, the reserves of sand mines licensed for exploitation in the region (An Giang, Dong Thap, Vinh Long...) will not meet the demand, and natural sand resources will soon be exhausted. At the same time, it will cause erosion, landslides on river banks, narrowing the mainland, changing the natural flow, negatively affecting the environment and social security life," said Mr. Sinh.

Mr. Tong Van Nga, Chairman of the Construction Materials Association, expressed concern that continuing to exploit soil and sand in the Mekong Delta would create many consequences.

Specifically, agricultural land will gradually disappear in the current context of many hydroelectric dams built by China, Laos, and Cambodia on the upper Mekong River. This situation leads to very little sedimentation; in general, it will affect food security, because the Mekong Delta is the rice granary of the whole country. In addition, the exploitation of soil and sand will make the Mekong Delta more susceptible to deep flooding.

Focus on using sea sand and thermal power plant ash as road filling materials

The leader of the Ministry of Construction informed that currently, there are many individuals and organizations in the country researching the use of alternative materials to river sand in traffic works such as sea sand, thermal power ash and slag; researching the use of reinforced concrete overpasses to replace part of the embankment to take advantage of the ability to supply large volumes of cement and steel domestically... However, this person said that it is necessary to carefully assess the environmental and ecological impacts of each solution, at different levels.

Mr. Tong Van Nga emphasized that it is necessary to change thinking, learn from what the world has been doing for a long time, which is to build reinforced concrete overpasses in the Mekong Delta.

"I recommend that leaders, managers, and experts should not be afraid of difficulties, but should be brave enough to innovate in implementing highway construction in the Mekong Delta by building overpasses. The overpass construction plan is especially suitable for locations with weak ground; if built with soil and sand, it will be much more complicated and costly," said Mr. Nga.

However, Mr. Nga recommended not to use sea sand to build roadbeds because doing so is contrary to international practice, which often uses sand and soil dumped into the sea to build islands and expand territory, instead of taking sand from the sea to build roadbeds. Not to mention, this also creates the risk of erosion in the Ca Mau peninsula.

Dr. Tran Ba ​​Viet, former Deputy Director of the Institute of Construction Science and Technology, said that the Ministry of Transport, as the investor of a number of highway projects in the West, needs to study solutions to build overpasses in weak, deep areas or areas where embankments must be raised or access roads must be extended.

"The total length of expressways being implemented in the Mekong Delta is 463 km, and the viaduct option can solve 20-30%, equivalent to more than 100 km. The viaduct option has better construction, maintenance, and quality costs than the embankment. The problem lies in whether the Ministry of Transport accepts the conversion or not, or if the embankment has been approved, it is forced to search for land and sand," said Mr. Viet.

Concluding the workshop, Deputy Minister Sinh affirmed that he would absorb and synthesize to report to the Prime Minister specific solutions to solve the problem of highway embankment materials in general, and in the Mekong Delta in particular. In particular, he will focus on solutions using sea sand and thermal power plant ash as road embankment materials; the overpass solution will be reported and proposed for application to future projects.