A study on the carbonation of binary and ternary blended cement mortar and concrete

ABSTRACT Carbonation of concrete has always been a durability concern leading to the corrosion of steel in reinforced concrete. The present paper deals with carbonation resistance of cement mortar and concrete when supplementary cementitious materials like fly ash and blast furnace slag partially replaces cement. The work had been carried out in two phases, first being the measure of carbonation depth and compressive strength of the samples with water binder ratios of 0.35, 0.5 and 0.65 to train the artificial neural network. Based on the results from carbonation depth, the consistency of Fick’s law of diffusion that governs the carbon dioxide (CO2) ingress into concrete has been ascertained with the help of linear-programming problem. In the second phase of the study, cement mortar samples of water binder ratios 0.4, 0.5 and 0.6 had been tested to verify the reliability of phenolphthalein indicator in identifying the depth of carbonation with the help of microscopic analysis such as Thermo gravimetric analysis (TGA). The same specimens have been used to identify the phases of crystalline materials of post-carbonation samples using X-Ray diffraction (XRD). An attempt has been made to quantify the carbonated products of calcium hydroxides and C-S-H.