EPS's applicability in Vietnam

       With the characteristics of EPS lightweight material mentioned above, it is seen that the possibility of applying EPS solution in construction on weak ground in Vietnam is feasible. Using EPS instead of conventional filling materials will help reduce the load of the construction, limit the increase of effective stress in the soil, thereby reducing, or even eliminating the settlement of the foundation. When the effective stress acting on the bottom of the foundation block is greater than the effective stress created by the soil column, the foundation block will experience settlement. If we replace the soil block in the foundation with lightweight material, EPS will cause relatively small effective stress. If the foundation depth is designed appropriately, the stress acting on the bottom of the foundation block will be approximately equal to the effective stress caused by the soil column. In this case, there will be no settlement or very small settlement. Thus, for projects using floating foundation method or projects damaged by subsidence of the soil mass inside, we can replace this soil mass with EPS material to reduce the load on the foundation bottom, thereby reducing or stopping the subsidence of the project.

       During the construction of the roadbed with embankment, the load acting on the ground gradually increases, so the settlement increases rapidly. After the construction is completed, the load remains constant, at this time only the settlement from creep remains. Depending on the structure of the ground, the settlement during the settlement from creep is large or small, proceed to remove the entire constructed soil mass, at this time the stress is 0. If we replace the embankment material with EPS, the load of the roadbed acting on the ground is only caused by the road surface structure layer and this load is much smaller than the load caused by the soil mass, the settlement generated is smaller than when using embankment material.

       Here are some suggestions for applying EPS materials in construction works in Vietnam:

        In order to apply EPS solutions in construction projects in Vietnam, it is necessary to conduct experimental studies to verify the suitability of the solution for actual conditions in Vietnam. Currently, Okasan Livic (Japan) is conducting a trial construction of an embankment using EPS material on weak soil in Phu My.

      EPS solution has been widely used in many countries for more than 40 years, with the advantage of EPS being a lightweight material, with uniform quality, good mechanical properties, suitable for construction on weak ground. Therefore, EPS is often used to reduce settlement of the construction and shorten construction time.

       However, with the geological conditions of Vietnam, the use of lightweight materials is a promising trend, especially when constructing roads on weak ground and handling subsidence of construction works. In order for the EPS solution to be applicable in Vietnam, it is necessary to continue researching and experimenting with geological and natural conditions as well as compiling appropriate design and construction standards. 

Excerpt: Bridge and Road Magazine No. 4, 2020