Introduction: Climate change (temperature rise and sea level rise) has a considerable influence on the behavior of concrete structures over time. All concrete degradation processes are connected to climate variables and the effects of climate change. The RCP8.5 (Representative Concentration Pathway) scenario, which is part of the report on climate change and level rise scenarios for Vietnam, predicts that the beginning of the 21st century will see an average annual increase in temperature between 0.8 and 1.1°C. In the mid-21st century, the temperature will likely increase by 1.8–2.3°C, with the temperature in the north likely increasing by 2.0–2.3°C and in the south by 1.8–1.9°C. In marine environments, the degradation of concrete structures can occur rapidly due to chloride-induced reinforcement corrosion. Furthermore, sea level rise is going to reduce the distance from the coastline to the structures and lead to increased surface chloride concentration. Methods: The evaluation of chloride penetration was based on the ASTM C1202 test (ASTM, 2012). The cylinder specimens (d = 100 mm, h = 200 mm) used for a rapid chloride penetration test (RCPT) were immersed in water for 28 days in a water-curing tank. Results: This study proposes a predictive model for analyzing the impact of climate change on the service life of concrete structures on Vietnam’s North Central Coast. The corrosion initiation time decreases by 16.5% when the effects of both temperature rise and sea level rise are taken into consideration. When only temperature rise is taken into consideration, the rate of reduction is approximately 9.0%. These results reaffirm that climate change has a significant effect on the corrosion initiation time of concrete structures located in a marine environment.
The work is devoted to the study of the characteristics of porous gypsum concretes obtained by the methods of foaming and gas formation using an acid blowing agent. Modification of the structure of gypsum stone makes it possible to obtain materials with high strength and good heat and sound insulation characteristics. The characteristics of the durability of the material largely depend on the type of pore structure, and the creation of the required pore structure can be carried out by various methods, among which the most studied and effective are foaming, which involves the introduction of gypsum dough into a pre-prepared foam and gas formation initiated by introducing gas-forming agents into the mixture at the stage mixing. In the work, samples of foam-gypsum and gas-gypsum were made, their strength characteristics and their thermal conductivity were evaluated. Using the method of optical microscopy, a comparative assessment of the macrostructure of cellular gypsum concretes and its comparison with gypsum stone was made. Using an electronic microscope, the microstructures of gas gypsum and foam gypsum were studied at x20, x100 and x500 magnifications. Fundamental differences in the resulting structures are established. From the array of data obtained, the most effective compositions were selected, proving the prospects for the development of porous gypsum materials. Based on the analysis and generalization of the obtained experimental data, recommendations are given on the use of the obtained compositions of porous gypsum concretes in civil engineering.
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