This paper presents a series of laboratory tests and evaluates the effect of polypropylene fiber inclusion on volume change behavior and soil-water characteristics of expansive soils. Specimens were statically compacted at maximum Proctor dry density and optimum moisture content with 0%, 0.5% and 1% polypropylene fiber inclusions by dry weight of the soil, and their volume change behavior was studied through swell-shrinkage and consolidation tests. The soil-water characteristic behavior, which is the most significant aspect of soils, was also obtained by a series of matric suction measurements using filter paper technique. It was concluded that polypropylene fiber inclusion is very effective in reducing the compression and swell indices and swell pressures as well as one-dimensional swell amount in saturated condition. Upon desiccation, shrinkage of reinforced soil reduced considerably, as the shrinkage limit increased by more than 50%. Therefore, fiber reinforcement can effectively reduce swell-shrink movement of expansive soils.

Reuse of dredged marine sediments for land reclamation is a sustainable method for disposing the large quantities of dredged spoil, accumulating every year worldwide. However, due to their high water content and low permeability, dewatering and self-sedimentation of the material takes a long time to be completed. Therefore, different methods, such as prefabricated vertical drains and vacuum preloading, are used to improve the consolidation properties of the dredged mud at the port of Brisbane. Among these stabilization methods, vacuum preloading is determined as the most effective method to increase the consolidation of the dredged mud. However, clogging during vacuum consolidation is undesirable. Therefore, electrokinetic stabilization draws attention since it is an environmentally friendly and time efficient method to dewater and consolidate dredged mud significantly. The effectiveness of the electrokinetic stabilization depends on the properties of the soil and the electrode configurations. One-dimensional and two-dimensional electrode configurations are the most popular configurations. In this study, the effect of one-dimensional electrode configuration, which is installation of electrodes in arrays of anodes and cathodes on consolidation parameters of dredged mud, is investigated. Based on this study, the dredged mud sediments can be stabilized using one-dimensional electrokinetic stabilization which resulted in improving compression index and coefficient of volume compressibility and reduction of soil plasticity index.

The purpose of this study is to investigate the changes in electric current, physiochemical properties (such as pH, electrical conductivity), and amount of salt content during the process, where stainless steel electrodes are used and the required power consumption is determined. Also, the ongoing settlement of the dredged sediments during the electrokinetic stabilization is also presented herein. This study shows how application of electric current affects the properties of the dredged mud. Electrokinetic stabilization is a method of improving soils by application of electric current to the soil through electrodes that was introduced by Casagrande in 1949. However, due to the complexity and lack of standard design it’s not a preferable option for geotechnical engineers to use. The type of electrodes and the type of drainage changes the efficiency of the method as a result of changes in soil resistivity. In this bench scale laboratory study, electrokinetic stabilisation is carried out in a cylindrical Perspex cell where the effect of stainless steel electrodes along with providing a double drain condition is investigated through changes in settlement, water content, soil resistivity, and the power consumption. As a result it is shown that significant amount of dewatering is achieved. The electrokinetic sedimentation of the dredged mud accelerated up to 20 times faster than self-weight sedimentation. The change of physiochemical properties of the dredged mud shows permanent changes in the soil structure. Placement of cathode at the bottom result in an increase in resistivity of the dredged mud and generation of the cracks near the cathode at the bottom which interrupts the flow of electric current through the soil mass.

Posidonia oceanica (PO) is the most plentiful seaweed of the Mediterranean Sea, which grows all along the coastal areas, forming widespread meadows. The leaf rejuvenation process of Posidonia oceanica typically occurs in fall when an increase in wave action causes the dead seaweeds to be transported and usually piled up along the coastal areas. This paper investigates the effect of PO ash stabilization on behaviour of an expansive clay. The ash was obtained by combustion of crushed PO pieces in a muffle furnace at 550°C. Atterberg limits, linear shrinkage, particle size distribution, one-dimensional swell, and unconfined compression tests have been carried out on natural soil as well as soil mixtures with 5% and 10% PO ash. There has been no significant improvement in the soil properties with 5% ash inclusion, whereas 10% ash has noticeably reduced the swell amount and increased the compressive strength. It is therefore concluded that there is a potential for the use of PO ash in geotechnical engineering applications.