The construction industry can reduce its high level of resource consumption and share of global carbon emissions by using and reusing bio based and recycled building materials. The research team behind the ReBuMat project wants to find out how this can be achieved in Vietnam.
View of a new neighbourhood under construction in Hanoi, Vietnam
Dirk Schwede
In Vietnam, the construction industry faces the particular challenge of differing climatic conditions that building materials must sustain. South Vietnam has a tropical climate with warm to hot temperatures year round and a wet season May through October. In contrast, the climate in North Vietnam is temperate subtropical with relatively cool temperatures November through April and a short hot period between May and October. What is more, Vietnam’s coastal areas are often hit by typhoons which bring very heavy rainfall. New build modern buildings in Vietnam must be able to withstand these extreme conditions.
Already today, more than one in every three people in Vietnam live in urban agglomerations. The country’s two largest cities Ho Chi Minh City and Hanoi each have a population of six million and three million respectively. More and more people are moving into the cities as the agricultural sector is losing relevance and the economy continues to grow. This fact is generating a high demand for new houses and other buildings.
The research team behind the German Vietnamese collaborative project ReBuMat is addressing this increased demand. Their aim is to explore and develop building materials and methods for energy efficient, resource conserving, sustainable construction, while taking into account the specific climatic conditions in Vietnam. They plan to develop standardized mass products for the building materials market in general and for industrial construction in particular. New buildings and components must withstand the challenging ambient conditions in tropical and subtropical climate with regard to structural physics. High humidity and wind driven rain pose particular challenges that must be taken into account during planning and development.
The three focus areas within the ReBuMat project include bio based building materials, recycled building materials and circular construction. All materials are tested in real world conditions on a specifically developed test bed in Vietnam.
Plant based building materials have many advantages over the mineral building materials that are typically used today. Plants grow back while the raw materials needed to produce mineral building materials, such as sand, loam and stone, are finite. The production of mineral building materials is also very energy consuming (cement production is just one example). The production of bio based building materials, on the other hand, requires much less energy. Moreover, plants actually absorb carbon dioxide from the atmosphere as they grow. When they are used to make bio based materials, the stored carbon is captured in the building structure in the long term.
However, it is important to ensure that the growing of plants to make building materials does not displace food crops for human consumption. Only in this way can we avoid food shortages and surging prices. The ReBuMat project therefore relies on agricultural waste products (such as rice straw), plants that grow on non agricultural land (e.g. reed or typha cut from wastewater treatment facilities or retention areas) and fast growing bamboo.
Materials from the transformation or demolition of buildings are currently mostly reused as fillers or aggregates. The aim of the ReBuMat research team is to reduce this kind of downcycling. Instead, recycled materials should be of similar quality and function as during first use. This is why the ReBuMat project is aimed at developing recycled high grade building materials that are attuned to Vietnam’s climatic conditions and will gain acceptance in the building materials market.
In addition to the reuse of concrete and broken bricks to replace virgin sand, glass offers a promising recycling option when made into foam glass. Window glass and waste glass that can no longer be used for making glass containers is to be made into moisture resistant insulation boards with many different use options. Window glass is mostly disposed of in large quantities as it cannot be recycled into an equally high grade product due to coatings and additives.
Ideally, all building materials should be used in such a way during construction that they can easily be separated when the building is transformed or demolished and henceforth used for similarly high grade secondary applications. For example, plasterboard (gypsum) impairs the recycling of construction waste and should therefore only be installed separately. Also, the materials that are needed for construction should be used efficiently. ReBuMat is aimed at developing construction systems that meet all these demands.
In Ho Chi Minh City in southern Vietnam, a container has been transformed into an open field test bed. One side of the container has been removed as this is where newly developed wall elements are installed and tested under real life conditions. The interior of the container has air conditioning. In this test environment, researchers are measuring the properties of the different wall elements with regard to heat transfer, water vapour permeability and wind driven rain intrusion. Another German Vietnamese project called CAMaRSEC has a similar test bed in northern Vietnam. In this way, valuable data is collected from both climate zones in Vietnam.
Vietnamese delegation visiting the open field test bed at Fraunhofer Institute for Building Physics in Holzkirchen
Dirk Schwede
Parameter sheets are used to document the properties of the building materials in development. In addition, the German research institutes that are involved in the project provide guidelines on the requirements for building materials in Germany. This expedites the process of drafting similar regulations in Vietnam.
The jointly generated knowledge will be published in scientific journals and also made available in a database on the project website. Moreover, wall elements made from the materials developed will be used as demonstration objects that can be exhibited at trade fairs or offered to interested higher education institutions. Furthermore, project partners are collaborating with industry in order to identify suitable mass market producers for materials and wall elements and thereby help make Vietnam’s construction industry more sustainable.
