چكيده به لاتين
In this study, the acceleration of sulfate ions attack, as one of the factors affecting the durability of mortar samples, was investigated. The attack of sulfate ions is the movement of sulfate ions into the concrete sample, which converts calcium hydroxide to calcium sulfate and converts aluminates to monosulfate and ethernygite, which causes expansion, reduction of mechanical properties and finally destruction of concrete and mortar. The degree of damage under attack by sulfates depends mainly on the amount of sulfate ions passing through the sample. However, sulfate attack is a slow process and it takes a long time to obtain reliable information about the effects of sulfate attack. According to ASTM C1012 standard, the effects of sulfate attack on mortar samples can be measured under changes in the length of prismatic samples, which requires a study of 6 to 24 months, depending on the study conditions. However, there are methods that can be used to accelerate the sulfate attack on concrete and its effects can be observed and measured in less time. As an example, research in this field has shown that increasing the concentration of sulfate solution, successive wetting and drying of samples, temperature changes in the sulfate medium, creating a dual sulfate and electrical environment and the combination of internal and external sulfate attack can accelerate Effects of sulfate attack. In this study, by inventing a dual sulfate-electrical environment, an attempt was made to reduce the time required for this experiment to a period of 3 months. Printed samples with water to cement ratios of 0.55, 0.485 and 0.4 were made and tested for 13 weeks and the results of placing the samples in an environment in accordance with ASTM C1012 standard with the results Were compared from the accelerated method. The results of expansion experiments, X-ray diffraction (XRD) and scanning electron microscopy (SEM) on the samples show that in the dual sulfate-electrical environment, the formation rate of gypsum and ettringite compounds as well as their amount and size. Has grown significantly. It should be noted that the final values of the expansion percentage for samples that were in environmental conditions in accordance with ASTM C1012 for 13 weeks for water to cement ratios of 0.55, 0.485 and 0.4, respectively, equal to 0.062%, 048%. 0.03 and 0.037% have been recorded that in dual sulfate-electric environmental conditions, these values are 1.14% (up to the fourth week), 2.115% (up to the twelfth week) and 1.131% (up to the week), respectively. Thirteenth) has increased that we have seen an increase of more than 50 times the ratio of expansion percentages, which ultimately comparing the results of the two methods has led to very good relationships.
