THE PROPOSED GEOBEADS ADDITION AS LIGHTWEIGHT FILL MATERIAL

The study aimed to develop an alternative material for dam and road embankments, especially in the area with soft soil, using Geobeads. There are many problems constructing embankments on soft soil, such as low bearing capacity, excessive and differential settlement, and slope stability. The subgrade must be stable to resist the weight of the fill construction and upper structure. The lightweight fill material is commonly used as an alternative to reduce the excessive and differential settlements by reducing the weight of landfills on the soft soil subgrade. In this study, the laboratory test was conducted to investigate the influence of Geobeads (GB) additions as lightweight fill material both as the dam embankment and the road embankment. This study aims to find a combination of GB, sand, and cement to fulfill the standard as an embankment material. Investigation of physical and mechanical properties represented that light embankment can be an alternative on soft soil. The Indonesia National Standard, 8062:2015, and the General Specifications for Road and Bridge Construction Work were guidelines for embankment cases. The falling head test executes the permeability coefficient. The CBR test was conducted based on ASTM D1883. The specimen has varied the percentage of EPS addition (20%, 30%, 40%) with 14 days of curing time. Based on the test results, both the permeability coefficient value and the CBR value decreased along with the increase in the percentage of EPS, where the coefficient of permeability (k) of the specimens around 10-5 cm/s and the lowest CBR at 40% GB was 30.02% which is the range still used as embankment material.

Geomechanical Behaviour of Uncemented Expanded Polystyrene (EPS) Beads–Clayey Soil Mixtures as Lightweight Fill

Lightweight fill can be advantageous in embankment construction for the purposes of reducing the (i) bearing pressures on the underlying soil foundation, (ii) destabilizing moments for constructed earthen slopes, and (iii) earth pressures acting behind retaining walls. This paper investigates the merits/limitations of particulate expanded polystyrene (EPS) beads mixed with clayey sand (CS) soil as lightweight fill, considering both geotechnical and environmental perspectives. The bench-scale geotechnical testing programme included standard Proctor (SP) compaction, California bearing ratio (CBR), direct shear (sheardox), oedometer and permeability testing performed on two different gradation CS soils amended with 0.5, 1.5 and 3.0 wt.% EPS, investigating two nominal bead sizes equivalent to poorly-graded medium and coarse sands. Compared to the unamended soils, the compacted dry density substantially decreased with increasing EPS beads content, from 2.09 t/m3 (0 wt.% EPS) to as low as 0.33 t/m3 for 3 wt.% (73 v.%) of larger-sized EPS beads. However, from analyses of the test results for the investigated 50 to 400 kPa applied stress range, even 0.5 wt.% (21 v.%) EPS beads caused a substantial mechanical failure, with a drastic decay of the CBR and compressibility parameters for the studied CS soils. Given the more detrimental environmental cost of leaving myriads of separate EPS beads mixed forever among the soil, it is concluded that the approach of adding particulate EPS beads to soils for producing uncemented lightened fill should not be employed in geotechnical engineering practice.