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Portland, magnesium phosphate binders sprout biological concrete

Source: Structural Technology Group of the Universitat Politècnica de Catalunya (UPC), Spain

Researchers at UPC/BarcelonaTech have patented a concrete that supports natural, accelerated growth of pigmented organisms, focusing on the effect of layering two cement-based materials for a finished structure and surface: 1) a conventional carbonated concrete, based on portland cement, with which technicians could obtain a material of about pH 8; and, 2) a concrete with magnesium phosphate cement binder, yielding a hydraulic, slightly acidic conglomerate that does not require any treatment to reduce its pH.

Owing to a vertical, multilayer configuration, UPC’s concrete fosters growth and development of families of microalgae, fungi, lichens and mosses. The university team is investigating the best way to promote the organisms’ accelerated growth on the concrete surface, and pinpoint a natural plant colonization process so that the surface acquires an attractive appearance in less than a year. A further aim is that the appearance of the façades constructed with the new material should evolve, showing color change according to time of year.

In order to obtain the biological concrete, pH factor aside, other parameters influencing the material’s bioreceptivity have been modified, including porosity and surface roughness. The result is a multilayer element in the form of a panel which, in addition to a structural layer, consists of a waterproofing layer, protecting the structural layer from moisture damage; biological layer, which supports colonization and allows water to accumulate inside while acting as an internal microstructure, aiding retention and expelling moisture; and, a discontinuous coating layer with a reverse waterproofing function, permitting rainwater entry.

From an environmental perspective, the new concrete absorbs and reduces atmospheric carbon dioxide due to its biological coating. At the same time, it has the capacity to capture solar radiation, making it possible to regulate thermal conductivity inside the buildings depending on the temperature reached. UPC officials cite the potential for commercialization of the product through a Catalan architectural precast producer, Escofet 1886 S.A.  —  UPC/BarcelonaTech, [email protected]