High-density claystone mixtures have been suggested as liners in radioactive waste repositories. However, this material can also be used as a liner in landfills. This study focuses on swelling characteristics of compacted claystone-bentonite at a low density for landfill applications. Claystone was taken from the Banjarbakula landfill project in Banjarbaru. The bentonite used is a commercially available bentonite from Indonesia. Claystone was mixed with 5, 10, 15, and 20% of bentonite on a dry weight basis. The mixture was statically compacted with moisture contents of 10, 15, and 20% to achieve a dry density of 16 kN/m3. A swell-load test was carried out using conventional oedometer equipment to obtain the swelling potential and swelling pressure of the samples. The results show that the swelling potential and swelling pressure increased with an increase in bentonite contents. At a bentonite content of more than 10%, both increased significantly. This research also revealed a linear relationship between swelling potential and swelling pressure.
Understanding soil shrinkage and retaining water is essential for learning more about the possibility of cracking of liner. Moreover, the factors that influence it are also important to know to improve the material tested as hazardous waste liners. The vapour equilibrium technique is widely used to control suction of compacted soils experiencing drying-wetting phenomena. It is considered to be inexpensive, simple, and has the ability to adequately control the suction applied to soil samples. This paper, therefore, describes its application in studying the shrinkage and water retention in compacted claystone-bentonite mixtures. This involved using five saturated salt solutions including potassium sulphate (K2SO4), potassium chloride (KCl), sodium chloride (NaCl), potassium carbonate (K2CO3), and magnesium chloride (MgCl2.6H2O). The sample was allowed to be in equilibrium with the relative humidity salt solution and a calliper was used to measure the dimensions every day up to when this was achieved. The results showed the bentonite in the mixture affects the amount of shrinkage and water retention while the sample’s initial moisture content was also found to be very influential on the magnitude of the primary and residual shrinkage. Moreover, the sample’s ability to hold water was almost the same without differentiating the initial water content at a total suction of more than 41084.91 kPa.
The seasonal and diurnal changes impact the backcalculated layer moduli for flexible pavements in different climatic regions. The HMA layer moduli showed minimal variation in the spring and fall seasons in every climatic area. Also, the HMA layer moduli were consistently higher, based on the deflections measured before noon. However, temperature correction, generally applied to HMA layer moduli, can eliminate the season, time, and temperature impacts of the FWD measurements. Since the base and subgrade layer moduli are backcalculated from the single measured deflection basins on the surface, temperatures and moisture conditions at the time of measurements can affect those material properties. Temperatures may potentially result in layer moduli values that are close to their representative in-field conditions. Based on the results, the preferred temperature ranges for FWD measurements are 55 to 70ᵒF and 65 to 75ᵒF in freeze and non-freeze regions, respectively, during any time of the day.
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