Physical Chemistry process for the synthesis of sustainable marine materials for the littoral preservation – EcoCorail

3 external laboratory are installed in front of the seawater for testing different environmental conditions (tide, immerged, different seawater composition).
A pilote project developped by the compagny (100m of beach and 100m of seawall will be protected against erosion)

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These last years, we attempt to a considerable increased of the erosion of the oceanic coasts that is the consequence of the seawater progressive increased and from violent climate phenomenon. French coasts are particularly affected with a step back of sand dunes and beach as well as cliff erosion.
Such phenomenon impact islands of the south pacific, in New Caledonia for example, threatening habitations. The multiple existing techniques in order to reduce erosion and its consequences are quite expensive, less environmentally friendly.
Recently, a new process developed by Géocorail SAS, used an innovative adaptation of the cathodic protection techniques in order to form a calcareous mineral agglomerate that permit to maintain in place beach sand or improve the resistance to landslide and dislocation of rocks used as seawalls. Its environmentally impact is very low (few materials supply are necessary), even positive. It could give rise to the reduction of some anthropics wastes.
This process, successfully used in situ on various sites, has demonstrated its potentiality and was the patented. On the other and, its application condition remains empirical. Numerous questions remain unknown about the germination and growing in volume of the calcareous scale.
Thus, the objective of this Ecocorail project is to understand all the mechanisms of the process, as well fundamental aspects (germination, growing) as applied aspect (porosity, mechanical resistance) before to apply it in a large scale. This project includes university laboratories (La Rochelle, Caen and New Caledonia) and the company Géocorail SAS.
The first task of the project will consist on studying the mechanisms of germination and growing of calcareous mineral concretion, to determine its properties (microstructure, structure, composition, stiffness, mechanical resistance) and to establish the relationships between formation and resulting properties. These studies will be carried out in laboratory, based on synthetic seawater and also on in situ experiments. Several sites for experimentation are planed in La Rochelle, Luc sur Mer, Wallis et Futuna and a pilot site developed by the company Géocorail SAS.
The second task will deal with the behaviour of the overall structure (agglomerate formed / metallic framework) with respect to corrosion. In the case of a stop of the cathodic protection, the steel in contact with seawater should corrode and corrosion products risk breaking the conglomerate.
Thus, third task will devoted to the valorisation of research knowledge developed in both precedent tasks for technologic transfer toward renovation construction sites and particularly towards pilot building site implemented by GéocorailSAS.
In the fourth task, the conglomerate formed will be tested as potential support with respect to the marine biological settlement. The long-term aim is to create and/or re-constitute life site for the flora and fauna in area originally rich in natural coral but recently destroyed by acidification of the oceans. A parallel objective concerns the ecological monitoring of oceans and sustainable development. This material could be used as a chronological indicator of seawater pollution due to co-precipitation: detection of metallic contaminates (nickel for example) could be performed.
The last task of the project will deal with the use of recycles materials from civil engineering or agro-industrial industry. The objective is to incorporate wastes (concrete aggregate, shell wastes) in the Géocorail formation and then to study the influence of such waste on the growing kinetics and mechanical performance in the conglomerate.