Monitoring accelerated carbonation on standard Portland cement mortar by nonlinear resonance acoustic test

摘要: Carbonation is an important deleterious process for concrete structures. begins when carbon dioxide (CO2) present in the atmosphere reacts with portlandite producing calcium carbonate (CaCO3). In severe carbonation conditions, C-S-H gel decomposed into silica (SiO2.nH2O) and CaCO3. As a result, pore water pH decreases (usually below 10) eventually steel reinforcing bars become unprotected from corrosion agents. Usually, of cementing matrix reduces porosity, because CaCO3 crystals (calcite vaterite) occupy more volume than portlandite. this study, accelerated carbonation-ageing conducted on Portland cement mortar samples to ratio 0.5. The evolution monitored at different levels ageing until almost fully carbonated. A nondestructive technique based nonlinear acoustic resonance used monitor variation constitutive properties upon carbonation. At selected ageing, compressive strength obtained. From fractured surfaces depth determined phenolphthalein solution. An image analysis quantify results resonant tests revealed progressive increase stiffness decrease material nonlinearity.