Research on Sustainable Building Materials in Vietnam

During the REBUMAT project period, the German Energy Agency (DENA) also carried out a study on building with renewable materials in Vietnam. The work was supported by the German and Vietnamese members of the REBUMAT project. In the final report, sustainable materials and their relevant construction parameters were compiled and suitable applications of materials in constructions were identified. The study is available on the ReBuMat website

(1) Construction method using pressed clay bricks in Vietnam

During the ReBuMat project, a construction method using pressed clay bricks was developed at the Hanoi University of Civil Engineering (HUCE) with additional funding from the Vietnamese Ministry of Construction (MoC) and buildings made of pressed clay were constructed for the rural population. These buildings are now available as demonstrators for this construction technique near Hanoi.

Demonstration project: Houses with unfired bricks (Photo: Prof. Nguyen Van Tuan, HUCE)

(2) Straw bale house using rice straws

Rice straw is produced in large quantities in agriculture in Vietnam (and in other countries in the region), sometimes several times a year. It is often burned in the fields after harvesting, which leads to extensive air pollution as far away as the cities, often even in neighboring countries. In many places around the world, straw is also increasingly used as a building material. Rice straw is probably particularly suitable for this purpose due to its properties as a building material.
As part of the ReBuMat project, a demonstration building made of rice straw bales in load-bearing construction (the loads are transferred via the straw bales) was constructed at the new campus of the Hanoi University of Civil Engineering in Ha Nam and is now available there as a ReBuMat demonstrator for students and the public.

Demonstration project: Report on straw bale houses (center: Virko Kade building the ReBuMat straw bale house)

The German-Austrian straw bale construction expert Virko Kade is leading the work. As part of the ReBuMat project, a chapter on building in other climate zones was added to his guide to building with straw bales.

The project partners from the Fraunhofer Institute for Building Physics and their colleagues from the Hanoi University of Civil Engineering (HUCE) are carrying out building physics measurements on the demonstration building to investigate the durability of straw bales as a building material under the warm and humid conditions in northern Vietnam.

Straw house construction, measurement monitoring and outlook

As a further demonstration project, the University of Applied Sciences Lübeck, together with the Hanoi University for Civil Engineering (HUCE), planned and organized the construction of a straw house on a HUCE university campus approx. 50 km south of Hanoi. The aim of the straw house construction was to demonstrate that rice straw can be used for load-bearing construction in a similar way to that used in Europe (left figure). In addition to assisting with the construction of the straw house, Fraunhofer IBP’s task was to develop a measurement technology concept , carry out initial measurements and estimate the risk of condensation and mold using a WUFI simulation (right figure).

Figure left and center: Construction of a model house with rice straw bales, which form load-bearing walls, on a university campus of the HUCE south of Hanoi by the project partners 2024 and determination of the mass-related moisture content of the straw wall

Simulation results

The simulation of the thermal and moisture behavior of the straw bale house under tropical boundary conditions: above the moisture values determined during construction, in the middle the simulation for the straw walls without plaster, and below the simulation of the straw walls with plaster. It can be seen that the walls with plaster tend to occasionally exceed the critical limit of 20 % moisture content by mass based on measurements in our latitudes. For this reason, the moisture behavior will also be monitored in the longer term by the HUCE University in Hanoi.

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