Waste disposal is one of the important problems in the world. In general, wastes are categorized into different groups, and there are some special landfills and methods for disposing of each of these waste materials. However, it should be noted that although there are some rules and regulations that try to reduce the impact of waste disposal, landfills have negative effects on soil, air, water, and natural life. One of the most important sources of pollution in landfills is the leachate that is generated by the decomposition of waste. Leachate can penetrate into the soil and water resources, contaminate them, and can affect human life. Leachate generation has five different phases and each of these phases contains some reactions that have a direct impact on the quality and quantity of leachate. Leachate has four main types of pollution and each of these pollutants can contaminate soil and water resources and be hazardous for aquatic and animals in the soil. In addition, some of these contaminations can enter the food chain and affect the ecosystem and human life. The negative impacts of landfills remain even years after the landfill is closed. Therefore, it is important to consider the short-term and long-term effects of landfills on their surroundings to protect the environment and human health.

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This paper studies the strength properties of compacted sand-bentonite landfill barrier material with and without cement addition at different periods of aging. Test results indicated that strength values both in compression and tension increased up to threefold in cement added samples, as well as enhancing the ductile behavior. Cubic modulus, described as the slope of the elastic portion of the cubic compressive stress versus strain curves is determined along with initial and flexural moduli, and all the strength and moduli values were correlated with each other. Finally, it is concluded that there is a marked improvement in strength properties and moduli with cement inclusion and that the effect of aging has been very effective.

A considerable amount of the globally produced ceramic goes to waste daily. Ceramic wastes that are sent to the landfills have negative effects on soil, water, and the environment, as they contain aluminum, silica and iron oxide. The waste water leaching to the soil contains insoluble particular matter or heavy metals and could damage the plants. The air emission of the ceramic waste dumping process is also very high and it has negative effect on environment and human health by spreading dust. Using waste ceramic dust in soil stabilization could be for better disposal of such waste. The usage of natural resources can be minimized as well as prevent additional environmental burden and emissions. For this purpose, three local clay soil samples from Erbil in North-Iraq were gathered and the effects of addition of waste ceramic dust on mechanical properties of these samples were experimentally examined in two different grading sizes. The ceramic dust with particle sizes passing sieve No.40 and sieve No.10, in the proportion of 0, 5, and 10% percentages were used. The study showed that with an increase in ceramic dust percentages, liquid limit, plastic limit, plasticity index, optimum moisture content of the clay decreased. On the other hand maximum dry density, unconfined compressive strength and California bearing ratio increased. The study showed that addition of No.10 gradation ceramic dust results in higher improvement compared to the same amount of ceramic dust in No.40 size. The current work concludes that soil stabilized with the right type and ratio of ceramic dust could be suitable for a sustainable highway construction subgrade by reducing the design thickness and potentially be more economic.