Development of laboratory tests to measure the growth kinetic of micro-algae of concrete in marine environment and comparison to in-situ experiments

Abstract

Climate change associated with population growth drive the building sector’s innovation in developing new ecological and sustainable concrete solutions. Regarding marine environment the rise of sea level is a main concern for several big cities across the world. New sea defense infrastructure around cities is expected to rise in the coming years. This will not be possible and accepted without any ecological compensation and thus by developing new ecological concrete range. The development of Bio-active concrete is one part of the solution: in addition to their conventional structural performance, these concrete promote marine bio-fouling and biodiversity. To reach this objective, a laboratory test was developed to screen different concrete surfaces and compositions. The bio-receptivity capacity of a concrete surface is measured by the amount of micro-algae on the concrete surface after four weeks test. This quick lab test supported the development of a new range of concretes called Bi-Layer porous concrete made up of one structural layer and one highly porous bio-active layer. These concrete were implemented as quay walls and reefs in Mediterranean and Atlantic sea. Very promising results were obtained after 18 months of immersion regarding bio-fouling activity and micro-algae diversity on the concrete confirming the results given by the laboratory test.