جستجوی مقالات مرتبط با کلیدواژه "آزمایش هیدرومتری دوگانه" در نشریات گروه "عمران"

Nowadays, the dispersion phenomenon is one of the main concerns for industrial and civil projects in southern regions of Iran. In this phenomenon, dispersive clay soil, under special situation, is dispersed and rapidly washed away. Due to the continuous developments in industrial and mineral additives, in this study metakaolin was used for soil improving dispersive soils. Researchers have always studied the use of additives for soil improvement. However, using cheap and environmentally friendly additives, such as natural pozzolans, are more desired. Natural pozzolans, are silica and alumina-silica materials with no apparent cement property but in presence of water, they make bonds with hydrate calcium and have cement properties. By reviewing previous studies, it can be seen that using pozzolanic materials are environmentally friendly, reduces energy consumption, reduces costs, reduces permeability and increases the chemical resistance of concrete. Metakaolin is a natural pozzolan with high permeability, with 50-55% SiO2 which reacts with Ca (OH)2 in room temperature and produces the calcium silicate hydrate (CSH) gel. Kolovos et al (2013) investigated mechanical properties of a soil improved by metakaolin. In this study, the optimum mix design of cement soil and its mechanical properties are investigated and the results show improved mechanical properties of soil. Wu et al (2016) studied the effect of metakaolin and cement on MHS strength and soil structure. The results show that adding metakaolin to soil reduces its sensitivity to water and significantly increased the uniaxial compressive strength and tensile strength of soil. Wianglor et al (2017) reviewed the effects of alkaline active metakaolin on compressive strength and particle structure of the improved mortar in 23 and 60 centigrade. The results show that increasing the amount of metakaolin and the temperature results in increased compressive strength and silicate and aluminate gel is apparently seen in mortar particle structure. In recent years, the compound effect of cement and metakaolin have rarely been studied, however there is no record for using metakaolin alone for soil improvement. This study aims to investigate the effects of different metakaolin percentages on reducing the clay dispersion potential, using crumb test, hydrometry, and also reviewing its geotechnical properties, such as Atterberg limits, maximum dry density, optimum humidity percentage, uniaxial compressive strength, and its validation using SEM.

The presence of dispersion in clays affects the behavior of these types of soils. Experience has shown that not paying attention to this issue has created many problems for civil projects and even led to their destruction in some cases. In the past, it was recommended not to use divergent soils, but today, due to the expansion of civil projects and the possibility of dealing with these types of soils, it is very important to investigate their behavior and find appropriate methods of improvement. Ibrahim et al. (2021) conducted a laboratory study on clay with different percentages of glass powder. They concluded that the maximum dry density and unconfined compression strength of modified soils increase with the increase in glass powder ratio. Different combinations of glass powder and cement were evaluated for silt stabilization according to different curing times. The results have shown that the durability and compressive strength of the modified soil increases with increasing curing time period (Baldovino et al., 2020). Using recycled glass powder can be an effective way to improve the geotechnical properties of soils due to its economic nature and its role as a recycled material in reducing environmental problems. Even though the effect of using glass powder in improving the resistance properties of soils has been investigated by researchers, the use of glass powder and its effect in improving problematic soils, especially dispersive clays, have not been specifically studied. Therefore, the purpose of this research is to investigate the effect of adding recycled glass powder on reducing the dispersivity potential of clay soils and improving their geotechnical properties.