Investigation of mechanical properties and durability of light-weight one-part alkali-activated slag concrete in sulfate environment Marjan Shahidi m.shahidi@cv.iut.ac.ir Date of Submission: 2020/00/00 Department of Civil Engineering Degree: M.Sc. Language: Farsi Isfahan University of Technology, Isfahan 84156-83111, Iran Supervisor: Kiachehr Behfarnia, kia@cc.iut.ac.ir Today, concrete has a very important role in the construction of various structures due to its advantages such as proper thermal insulation, good ductility, cheapness and fire resistance. In addition to the benefits of concrete, the destructive environment effects, poor tensile loads and high weight of structures are among the issues that should always be considered by designers and builders. The vulnerability of Portland cement concrete to some environmental aggressors such as acids, sulfates, gases, chlorides, seawater, as well as melting and ice cycles can in some cases cause problems and lead to concrete degradation. Therefore, to eliminate the defects mentioned in cement concrete, lightweight aggregates and active alkali materials were presented for the production of lightweight active alkali concretes. In this study, an attempt was made to produce and study single-component slag, which is similar to cement concrete in terms of production, using the materials available in the country. The purpose of this study was to investigate the effect of aggregate type, slag grade and processing type on the performance of light alkali activated concrete of single-component slag in magnesium sulfate environment and also to investigate the mechanical properties of this type of concrete. Alkali activated lightweight concrete Concrete slag is produced from a solid activating mixture of 5-aqueous sodium metasilicate, slag, lightweight aggregate and water. Because the purpose of this study was to investigate the effect of slag, type of aggregate and type of processing, in all these designs, a fixed mixing scheme was used and the only variable parameters in the mixing schemes of different amounts of slag were different combinations of lightweight aggregates. In the present study, in order to lighten lightweight concrete, 4 combinations of ordinary sand, light sand, ordinary sand and light sand and light sand and ordinary sand have been used. Also, two grades of 400 and 475 slag have been used to investigate the grade of slag in this research. In order to evaluate the mechanical properties of lightweight alkali activated concrete, single-component slag changes in compressive strength at the ages of 7, 28, 90 and 180 days, tensile strength changes at the age of 28 days and flexural strength at the age of 28 days in both water treatment and coating processing Plastic was measured. Also, to evaluate the performance of activated alkali lightweight concrete of single component slag in sulfate medium, the samples were placed in water and plastic processing media for 28 days and then by placing the samples in magnesium sulfate medium, 5% changes in compressive strength, mass and volume. Samples were measured at 60, 90 and 180 days of age. The experimental results showed that the increase in slag in the active alkali concrete of single-component slag increases the compressive strength due to the increase in the concentration of the adhesive paste. Also, the processing in plastic coating shows better performance than the processing in water, but with increasing age of the samples, the samples in water processing show better performance. Concretes made of light-grained sand show significant resistance due to their light age at 7 to 180 days. In magnesium sulfate medium, the stability of the samples is higher by increasing the slag grade. The use of lightweight grain has a positive effect on the performance of active alkali concrete of single-component slag in the processing environment in plastic coatings, but by placing the samples in the environment of magnesium sulfate, the processing samples in water show better performance. By placing the samples in magnesium sulfate medium, as the age of the samples increases, the mass decreases in most of the samples. Also, all samples placed in magnesium sulfate medium are associated with an increase in volume. Keywords: Alkali activated lightweight concrete, single component slag, 5-aqueous sodium metasilicate, magnesium sulfate medium, grain style, plastic coating treatment, water treatment, mechanical proper