The research of carbonation of existing concrete structures presented in the article was executed in the process of conducting a technical survey of the building. According to the results of the study, places with varying degrees of carbonation were identified. A method for preparing the phenolphthalein solution used in the examination is described. A methodology for testing structures to determine the degree of carbonation is presented. The results of measuring the degree of carbonation of structures by the phenolphthalein method are presented. The data obtained show that the concentration of carbon dioxide has a significant effect on the corrosion process of reinforcing bars and the loss of the bearing capacity of structures during the operation of an existing building. A favorable range of pH values for concrete structures during operation is considered. The average actual depth of the neutralized concrete layer is determined. The method of restoration of building structures exposed to the carbonation reaction is described. The impact of carbonation on reinforced concrete structures during the operation of the building is assessed. The results of the restoration work are presented.
Presented here are the results of assessing the effect of elevated temperature on the strength characteristics of reinforced concrete structures during operation. Described here are the features of the technical inspection of structures subjected to temperature effects (after a fire). The strength class of reinforced concrete structures was determined before temperature exposure (in places that were not exposed to fire) and after in the course of the study. Presented are the results of measuring the strength of concrete by the direct method of pulling off with spalling, as well as the results of verification calculations of reinforced concrete structures exposed to temperature effects. When performing verification calculations, the percentage of reduction in the bearing capacity of structures was established. Based on the results of the study, the percentage ratio of the decrease in the strength of prefabricated reinforced concrete structures after a fire during the operation of the facility was established.
The article presents the results of a technical inspection of the state of the structures of the object. To conduct the study, horizontal structures of the sludge pool that were exposed to the carbonization reaction were taken for the objects under investigation. Defects and damages of the considered structures revealed during visual inspection are described. The degree of carbonization of reinforced concrete structures was determined by the phenolphthalein sample method. According to the results of the technical inspection, a verification calculation of the beam was carried out in order to determine its bearing capacity for assessing the suitability for further operation after restoration and strengthening. The calculation was performed using software. Based on the calculation results, data on the bearing capacity of the beam reinforced with composite materials were determined. The option of restoring and strengthening the beam using external reinforcement based on carbon fibers FibArm 230/150 is presented. The restoration was carried out taking into account the carbonized concrete layer. Based on the results of the study, an assessment is given of the application of an integrated approach to the restoration and strengthening of structures with composite materials, taking into account the carbonized concrete layer.
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