Polymer concrete, which contains silica fume powder and vinyl ester resin as two replacements for Portland cement, has improved mechanical properties and durability compared to ordinary concrete. Thus, this kind of concrete is considered to be a high-strength concrete that is resistant to corrosion and chemical attacks. In this paper, the effects of the combination of silica fume powder and vinyl ester resin as two Portland cement replacements on the workability and slump value, initial and final water absorption, compressive and tensile strength, and failure and fracture paths of the polymer concrete have been investigated. All investigations have been based on 16 different polymer concrete mixture designs. The results indicate that the optimum percentages for a combination of silica fume and vinyl ester resin, which has the maximum compressive strength (34.26 MPa) and the maximum tensile strength (4.92 MPa), are a combination of 10% silica fume and 5% vinyl ester resin. To evaluate the durability of polymer concrete, the water absorption of all mixture designs has also been measured. Accordingly, the mixture design, which includes a combination of 15% vinyl ester resin and 5% silica fume, has a minimum initial and final water absorption equal to 0.62% and 1.95%, respectively.

The widespread application of reinforced concrete structures in different environmental conditions has underscored the need for effective maintenance and repair strategies. These structures offer numerous advantages, but are not impervious to the deleterious effects of chemical deterioration. The outcomes of this research hold significant implications for the management system of reinforced concrete structures. This study proposes the utilization of a fuzzy expert system as a means of enhancing the diagnosis of chemical deterioration in reinforced concrete structures that is a valuable tool for engineers and decision-makers involved in the maintenance and repair of these structures. The fuzzy expert system serves as an intelligent tool that can incorporate various symptoms of deterioration and inspection data to improve the accuracy and reliability of the diagnostic process. By integrating these inputs, the system evaluates 21 different data points, each representing a specific aspect of deterioration, on a scale ranging from 0 to 100. This numerical representation allows for a quantification of the level of deterioration, with 0 denoting minimal deterioration and 100 indicating severe deterioration. The effectiveness of the fuzzy expert system lies in its ability to process the vast amount of data and apply fuzzy operations on 352 fuzzy rules. These rules define the relationships between the inspection data, the type of deterioration, and its extent. Through this computational process, the fuzzy expert system can provide valuable insights into 10 distinct types of chemical deterioration, facilitating a more precise and comprehensive diagnosis. The implementation of the fuzzy expert system has the potential to revolutionize the field of diagnosing chemical deterioration in reinforced concrete structures. By addressing the limitations of traditional methods, this advanced approach can significantly improve the clarity and accuracy of the diagnostic process. The ability to obtain more precise information regarding the type and extent of deterioration is vital for developing effective maintenance and repair strategies. Ultimately, the fuzzy expert system holds great promise in enhancing the overall durability and performance of reinforced concrete structures in various environments.

Life-Cycle-Cost (LCC) analysis of corroded structures located in corrosive marine environments considers the time-dependent resistance and loading affect, and repair and maintenance scenarios applied during life time of these structures. Finding the optimum repair and maintenance scenario for a corroded reinforced concrete (RC) structure is a significant process to select a repair and maintenance scenario with minimum LCC and maximum service lifetime. For this purpose, a finite element (FE) model is applied to assess the time-dependent capacity of corroded RC circular column using nonlinear analysis. In corrosion initiation phase, empirical chloride diffusion and surface chloride concentration models obtained for silica fume RC under long-term exposure in splash zone of Bandar-Abbas coasts, located in south side of Iran, and in corrosion propagation phase, empirical corrosion current density model for splash zone of a marine environment in literature is used for modeling of corrosion process. In this analysis, the influence of a number of repair or rehabilitation scenarios on the performance of a corroded circular RC column due to chloride-induced corrosion, including five different concrete surface coatings used on the external surface of concrete, four different increasing concrete cover thickness and using the new longitudinal and horizontal reinforcements after the initial cracking of concrete cover are investigated. These 11 different scenarios with considering a scenario without any repair are optimized by Genetic Algorithm (GA) based on minimum LCC cost and 40 years failure time in terms of corrosion.

Chloride-induced corrosion is a key factor in the premature corrosion of concrete structures exposed to a marine environment. Fick's second law of diffusion is the dominant equation to model diffusion of chloride ions. This equation is traditionally solved by Finite Element Method (FEM) and Finite Difference Method (FDM). Although these methods are robust and efficient, they may face some numerical issues due to discretization process. This study solves the Fick's equation using the Element-Free Galerkin (EFG) method as well as traditional FEM and FDM. The results of these numerical methods are compared together, and validated with the analytical solution in special cases. The results show that the EFG method predicts the service life of the concrete structures, more accurately than the other methods, and exhibits the lowest displacement error and energy error for a constant diffusion coefficient problem. FDM can be performed very efficiently for simple models, and the displacement errors produced by this method do not differ considerably from the EFG results. Therefore, FDM could compete with the EFG method in simple geometries. FEM can be used with a sufficient number of elements while the convergence of the results should be controlled. However, in complicated models, FEM and especially the EFG method are much more flexible than FDM.

The chloride corrosion of reinforcing steel in reinforced concrete (RC) structures is a significant reason for premature deterioration and failure of RC structures in aggressive environments such as the Persian Gulf region. This is one of the major sources of engineering and economic problems in developed countries. On that account, modeling chloride permeation and investigating different methods for the repair and maintenance of RC structures exposed to corrosive environments are considered to be essential for optimizing the service life and life cycle cost of these structures. In this research, a finite element model is applied to assess the time-dependent capacity of corroded RC structures applying nonlinear analysis; this includes the impact of corrosion on inelastic buckling and low-cycle fatigue degradation of reinforcements. In this analysis, the influence of shotcrete repair after the initial cracking of concrete cover as a rehabilitation method on the performance of a corroded square RC column due to chloride-induced corrosion is investigated.