Corrosion of the reinforced concrete (RC) structures has been affecting the major infrastructures in U.S. and in other continents, causing the recent several bridge collapses and incidents. While the theoretical understanding is well-established, the reliable prediction of the corrosion process in the RC structural systems has hardly been successful due to the inherent uncertainties existed in the electrochemical corrosion process and the associated material and environmental conditions. The paper proposes a computational framework to develop evidence-based probabilistic corrosion initiation models for the reinforcing steels in the RC structures, which predicts the corrosion initiation time and quantifies the inherent variances considering various acting parameters. The framework includes: probabilistic modeling with Bayesian updating based on the sets of previously generated experimental data; Bayesian model/parameter selection considering various parameters, such as material properties and environmental conditions; corrosion reliability analyses to predict the probabilities of the corrosion initiation at given time t, structural configurations, and environmental conditions; and sensitivity analyses to measure and to rank the influences of each acting parameter and its uncertainty to the probabilities of the corrosion initiation. Total of 284 sets of experimental data exposed to the coastal atmospheric environments are used for the modeling. The goal of the Bayesian model selection presented in this paper is to obtain the most accurate and unbiased model using the simplest form of expression. The developed example corrosion model is currently limited to the initiation of diffusion-induced corrosion. The model can be updated, improved, or modified upon future available sets of data. The research contributes to the decision making to improve the corrosion reliability, corrosion control, and further the structural reliability of corroding structures.

The objective of this paper is to report the improvement of sustainability through the increase of reinforced concrete corrosion resistance by using a blended cement and fly ash. Different reinforced concrete mixtures were prepared with partial substitution of a manufactured blended cement with fly ash from a thermal power plant in Andorra (Teruel, Spain). These mixtures were manufactured using three different water/cement ratios (0.46, 0.59, and 0.70) and three substitution percentages of cement by fly ash (0%, 25%, and 50%). The test cylinders underwent an accelerated carbonation process and exposure to different chloride levels, with the aim of characterizing the corrosion level of the different mixtures. The addition of local FA matched or even improved the resistance of the control mixture against carbonation and chlorides.

The present investigation establishes the basis for future studies in the southeast of México for the improvement of building materials by combining regional organic and inorganic nanoparticles in admixtures to formulate cement mortars with durability potential in structures of concrete. The characterization of the organic extract of Albzia tomentosa by nuclear magnetic resonance (NMR) revealed the presence of epicatechin (tannin related) and sucrose. Calcium zinc hydroxide dihydrate nanoparticles (CZ NPs) showed the highest surface area of 60.7 m² g⁻¹. The electrical resistivity, propagation of ultrasound velocity and water absorption by capillarity properties were individually evaluated for the organic extract, the inorganic nanoparticles and their admixtures in cement mortars, at a curing time of 7, 28 and 96 days with and optimal concentration of 5 mg mL⁻¹ of the added additives. The best results were obtained at 96 days showing slightly but clear improvement of the electrical resistivity (23.40 ± 0.022 kΩ cm, 22.40 ± 0.004 kΩ cm and 22.29 ± 0.013 kΩ cm), propagation of ultrasound velocity (1370 ± 10 m s⁻¹, 1345 m s⁻¹ ± 6, 1310 ± 9 m s⁻¹) and capillary coefficient (0.0044 kg m⁻²s^−1/2, 0.0045 kg m⁻²s^−1/2 and 0.0049 kg m⁻²s^−1/2) properties of the cement mortars with CZ NPs, extraction Albizia solution (EAS) and CZ NPs + EAS respectively when compared to the mortar control (19.91 ± 0.036 kΩ cm, 1266 ± 15 m s⁻¹ and 0.0082 kg m⁻²s^−1/2).