BUILDING SMARTER WITH HIGHTECH MATERIALS

POLYMER CONCRETE: MATERIAL MADE OF DESERT SAND

After water, according to the United Nations Environment Programme (UNEP), sand is the second largest resource being extracted and traded around the globe. And with negative consequences for the environment: for example, with the removal of sand along coasts and riverine landscapes, sediment is being increasingly eroded, and this in turn causes rivers to flow faster and beaches to be washed away. In addition, sand extraction causes riverbanks to become unstable and, in the long term, undermines their protective function: the increasing flooding of adjoining land endangers the habitat of many animal species. [2]

In the future, polymer concrete could help conserve the stocks of river sand that are currently being used above all in the production of conventional concrete. In contrast to the latter, this innovative building material doesn’t contain cement, but a plastic (polymer) that provides bulk to the composite material – usually gravel or sand. The plastic enables the bulking agents to adhere so well that even previously unusable types of sand can now be used in concrete production.

The polymer concrete developed by the Thuringian company PolyCare, for example, uses desert sand as a bulking agent – on site and directly where it’s found. [3] This makes long-distance transportation unnecessary and reduces CO₂emissions that would otherwise have been caused during the journey. Further advantages of polymer concrete: adding polyester resins makes it lighter than cement concrete. Its smooth, low-porous surface also makes it less sensitive to weathering or UV radiation. [4] And because of its short setting time – that is, the time it takes for the concrete to reach a specified consistency – the material is able to bear loads at an earlier stage in the building process. In this way, it enables the quick and inexpensive construction of living and utility spaces. The first polymer-concrete houses using desert sand have already been built in Namibia. [5] PolyCare’s developers are currently looking into the question of how to replace petroleum-derived polyester resins with more sustainable substances. [6]

SELF-HEALING CONCRETE: FIGHTING CRACKS WITH BACTERIA

Another milestone on the road to the future in materials research has been the discovery of self-healing concrete. The scientists of Delft University of Technology in the Netherlands are the pioneers in this field. The principle behind this miracle material is that limestone-producing bacteria close gaps in the concrete all by themselves, thereby extending the durability of buildings and making expensive renovations unnecessary. [7]

This is how it works: bacteria are set into the new type of concrete mix with the aid of clay pellets not more than a few millimetres in size and also containing nitrogen, phosphorus and nutrients. If water enters the concrete through cracks, the micro-organisms absorb the nutrients and produce a kind of limestone (calcium carbonate) [8] that fills the cracks that have formed in the concrete. The researchers are currently working on how to provide the bacteria with optimal living conditions. Particular attention is being paid, for example, to enabling the micro-organisms to produce maximum amounts of limestone within this “organic concrete”. [9]

The use of the self-healing material is especially worthwhile in the case of large-scale concrete structures. One example of its being put into practice is a firewater basin in the port of Rotterdam. Manufacturers claim that the bacteria is able to repair cracks up to 0.8 millimetres wide. [10]

SMART WOOD AS A BUILDING MATERIAL OF THE FUTURE

As a renewable raw material, wood is becoming increasingly attractive for the construction industry. According to one study [11], using this sustainable building material instead of steel and concrete could prevent 14 to 31 percent of global CO₂ emissions. Various solutions that would give wood completely new properties are currently under development. For example, as part of their “WoodNano Tech” project, researchers at the Royal Institute of Technology in Stockholm are working on making wood ultra-thin and almost transparent. [12]

In order to produce this new material, the scientists extract from the wood a component called lignin, which holds the cellulose fibres together. In the next step, they soak the material with a plastic. This innovative process makes it possible to provide wood with additional properties such as thermal conductivity: during the day, windows made of the new building material could store heat that could then be radiated into the house at night. Unlike glass, this transparent wood doesn’t break and is both weather-resistant and fireproof. [13]

The Swedish researchers are currently investigating various fields of application for the transparent wood. This renewable and low-cost building material is also being considered for use in the energy sector, for example in the production of solar cells. [14]

SOURCES AND BIBLIOGRAPHY

[1] https://www.pwc.com/vn/en/industries/engineering-and-construction/pwc-global-construction-2030.html

[2] https://unepgrid.ch/sand/
[3] https://poly-care.de/index.php/de/polycare-de
[4] https://www.baustoffwissen.de/baustoffe/baustoffknowhow/grundstoffe-des-bauens/polymerbeton-definition-eigenschaften-einsatzbereiche-entwaesserungsrinnen-rohre-kabelkanaele-lichtschaechte-treppenstufen-fassadentafeln-fensterbaenke/
https://poly-care.de/index.php/de/polycare-de/polymerbeton
[5] https://poly-care.de/index.php/de/polycare-de/warumpolycare-de
[6] https://www.sueddeutsche.de/wissen/baustoff-der-welt-geht-der-sand-aus-1.3588083-2
[7] https://www.tudelft.nl/citg/onderzoek/stories-of-science/zelfherstellend-beton/
[8] https://www.baustoffwissen.de/baustoffe/baustoffknowhow/grundstoffe-des-bauens/selbstheilender-beton-bakterien-gegen-risse-betonschaeden-hendrik-jonkers-tonpellets-bio-beton/
[9] https://www.tudelft.nl/en/technology-transfer/tech-investment/patents/selection-of-tu-delft-patent-portfolio/self-healing-concrete-materials-that-can-repair-itself/
[10] https://www.ais-online.de/m2/76/5153276/pdf/28/21375528px595x842.pdf
[11] https://www.tandfonline.com/doi/full/10.1080/10549811.2013.839386#.UznEccdlbx5
[12] https://phys.org/news/2019-11-transparent-wood-material-future.html
[13] https://www.sueddeutsche.de/wissen/baumaterial-glas-aus-holz-1.4398164https://www.spektrum.de/news/durchsichtiges-holz-als-waermespeicher/1636858, https://www.spektrum.de/news/durchsichtiges-holz-als-waermespeicher/1636858
[14] https://cordis.europa.eu/project/id/742733