In addition to its civil engineering properties, concrete also has an architectural and aesthetic function. When the concrete structure ages, the visible appearance of the surface gradually changes as it is exposed to the environment, i.e. weather, pollution and biological growth. Often this aging does not take place homogeneously over the surface which combined with dirt and biological deposition of the surface reduces the aesthetic appearance of concrete. Modifications of concrete surfaces by targeted deposition of surface functional additives, e.g. with agents that make the surface hydrophobic, allow to minimize the visual aging and thus improve the aesthetic durability of the concrete. The long-lasting hybrid sol-gel systems developed and applied for plastic and metal surfaces are not always applicable to more complex concrete surfaces due to its heterogeneous, porous and rough nature. Silane-based water repellent and easy-to-clean materials using modified silicon precursor are synthesized and applied on concrete substrates. The initial chemical and physical properties of the treated and untreated surface are tested (surface wettability /hydrophobicity, surface morphology, penetration depth, adhesion, and effect of pH). The interactions between the applied chemical protective treatments and concrete surface are examined to obtain a more fundamental understanding of the physical and chemical properties responsible for the aging of the concrete surface. Studies of the microstructural and porosity changes of untreated, treated and leached specimens using SEM, ESEM and SEM-EDS are performed. The leaching test also serves as a first test of the durability of the applied sol-gel based system on the concrete surface.
Journal: TechConnect Briefs
Volume: 1, Nanotechnology 2008: Materials, Fabrication, Particles, and Characterization – Technical Proceedings of the 2008 NSTI Nanotechnology Conference and Trade Show, Volume 1
Published: June 1, 2008
Pages: 451 - 453
Industry sector: Advanced Materials & Manufacturing
Topic: Coatings, Surfaces & Membranes