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Go to Editorial ManagerExpansive soil poses significant challenges for civil engineers worldwide since it seriously affects the structures built upon it. This soil has a very active group of minerals called montmorillonite, which is responsible for the significant volume change it exhibits. For a number of years, chemical additives have been utilized to stabilize soil, with various levels of success. Soil stabilization has involved the use of a variety of additives, including cement, lime, polymers, salts, and combinations of these. However, lime is very often used for expansive soil stabilization as it improves the soil's mechanical properties. The effects of adding three percentages of lime (3%, 6%, and 9%) to expansive soil to improve its engineering properties are investigated through several tests. The laboratory tests consist of standard compaction, sieve analysis, atterberg limits, hydrometer, California bearing ratio, consolidation test, swelling potential, and specific gravity. The test results displayed that the plasticity index, liquid limit, swelling potential, and maximum dry density, specific gravity decreased using (3%, 6%, and 9%) lime. In contrast, the plastic limit, and optimum moisture content increased using (3%, 6%, and 9%) lime. The California bearing ratio is increased from (12.13% to 14.65%) by adding (9% L). The swelling index and compression index are decreased from (0.070 to 0.030) and from (0.581 to 0.193) respectively by adding (9% L). The swelling percentage is reduced from (18.77% to 6.03%) by adding (9% L).
Soil’s characteristics are essential for the successful design of projects such as airports runway and flexible pavement. CBR (California Bering Ratio) is one of the significant soil characteristics for highways and airports projects. Thus, the CBR property can be used to determine the subgrade reaction of soil through correlations. Many of the soil geotechnical parameters such as compaction characteristics (Maximum Dry Density, MDD; Optimum Moisture Content, OMC), and consistency parameters (Liquid Limit, LL; Plastic Limit, PL; Plasticity Index, PI) can be in charge of changes that happen in soil CBR value. Soaked and/or non-soaked conditions of soils also affect CBR value. Hence, testing soils in a laboratory for CBR calculation is time-consuming that needs notable effort. Therefore, this study aims to generate some useful correlations for soil’s CBR with compaction and consistency parameters for 85 samples of fine-grained soils. The study trials were applied on natural soil samples of various places in Sulaimani Governorate, Northern Iraq. Statistical analysis has been carried out by using SPSS software (Version 28). Soaked CBR is counted, which is important for conditions such as rural roads that remain prone to water for few days. Based on the statistical analysis, there is a significant correlation between LL, PL, PI, MDD, and OMC with CBR as the dependent variable as a single variable equation with R2 of 0.7673, 0.5423, 0.5192, 0.6489, and 0.51, respectively. In addition, the highest value of R2 correlation was obtained between CBR value with consistency and compaction properties as a multiple regression equation with R2 of 0.82. The obtained equations for correlation purposes are successfully achieved and can be used, notably, to estimate CBR value.
Soil reinforcement techniques have been successfully used to improve the shear properties of weak soils in recent years. To improve the utilization of waste resources and promote sustainable development of infrastructure amid rapid urbanization, one potential option for reinforcement materials is human hair fibers (HHF). Because it is a natural fiber, there are risks to human and environmental health associated with the improper disposal of human hair fiber, an occurring waste product that does not decompose completely. This fabric is abundant, has a high reusability rate, and is ideal for use as a reinforcement to address waste management issues and make the most of inefficient or unnecessary manufacturing websites for long-term sustainability. The CBR test was executed on several samples with diverse fiber possibilities to evaluate the engineering properties of the randomly placed HHF in clayey soil samples using fibers whose average length was 50 mm and whose diameter ranged from 60 to 80 microns and compared the outcomes to those of unreinforced soil. The soil sample was treated with different percentages of Human Hair fiber (0%, 0.75%, 1.5%, 1.75% and 2.25%). The results showed that the value of CBR of the soil sample decrease at 0.75% of HHF and then increased up to 2.25% of HHF.