Energy efficient nano-modified renders with CO2-storage potential (CCSRender)

Anthropogenic activities over the past century have caused a dramatic increase of carbon dioxide (CO2) concentration in the atmosphere. A potential solution to this crucial problem is the storage of CO2 through mineral carbonation, which comprises one of the most promising carbon capture and storage (CCS) technologies. The aim of the CCSRender project was the development of novel, environmentally-friendly lime-based renders with the ability to sequester CO2 directly from the atmosphere via in situ mineral carbonation. This was achieved through the addition of suitable mafic/ultramafic rocks (including quarry waste materials) in nanoscale to the aforementioned composite building materials. The first stages of the CCSRender project included sampling of mafic/ultramafic rocks and quarry fines from Cyprus and Hungary. Based on their mineralogical composition, the most promising samples were subjected to the ball milling process in order to create nano-sized rock powders with enhanced CO2 sequestration capacity. The goal was to mimic and accelerate the natural process of mineral carbonation by reducing the particle size of specific rock samples down to the nanoscale range. During this 2-year project, a significant number of ball milling experiments were performed, aiming to determine the optimum milling parameters for each individual rock sample.

The research team focused on the development of sufficient quantities of the most promising nano-sized powders in order to be used as additives during the preparation of render mix designs.A significant number of nano-modified render mixtures were prepared by adding the new nanomaterials at different quantities (in partial replacement to the lime binder). The end-products were characterized through a wide range of analytical methods and laboratory tests. The results revealed that the nano-modified renders showed a significantly denser microstructure compared to the reference specimens, due to the nano-filler effect, in combination with the enhancement of the carbonation reactions. This clearly indicated that the use of the aforementioned nano-additives in renders can (i) notably accelerate the carbonation reactions at ambient conditions, thus enhancing the early-age physico-mechanical properties of the end-products, and (ii) contribute to the mitigation of atmospheric CO2 concentrations. The positive results of the CCSRender project were further supported by pilot applications, which confirmed the enhanced performance of the new nano-modified building materials under real exposure conditions. The advantage of the aforementioned methodology, besides enhancing the carbonation reaction and physico-mechanical properties of the composite material, is that it could also contribute to the reduction of the CO2 emissions associated with the production of lime, due to the partial replacement of the latter by the new nano-additives.The approach proposed in the framework of the CCSRender project becomes significant since the COP21 Paris Agreement aims to avoid future dangerous climate changes by limiting global warming to well below 2 °C above the pre-industrial levels. Accordingly, the development of environmentally-friendly building materials through the sustainable exploitation of quarry waste materials worldwide, could notably contribute to the strategies for the mitigation of global greenhouse gas emissions.Τhe project results have been presented to the scientific community through 4 publications in peer-reviewed international scientific journals and 7 peer-reviewed articles/abstracts in international conferences (http://ccsrender.org/).

Project Details