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Lightweight fill
Published in Jay Ameratunga, Sivakugan Nagaratnam, M. Das Braja, Soft Clay Engineering and Ground Improvement, 2021
EPS as ground improvement is mostly used in embankments and slopes. In soft clay engineering, EPS has become more popular over the last two decades. For those who wish to research further, the following documents provide further information and geotechnical guidance on EPS as a ground improvement material:Christopher et al. (2006) Geotechnical Aspects of PavementsFHWA (2017). Ground Modification Methods – Volume IStark et al. (2004a). Geofoam Applications in the Design and Construction of Highway Embankments, NCHRP Web Document 65.PennDot (2018). Geotechnical Engineering Manual, Publication 293. Pennsylvania Department of Transportation.SHRP2 (2014). Geotech Tools: Geo-construction Information & Technology Selection Guidance for Geotechnical, Structural, & Pavement Engineers.The factors of safety that apply for EPS design according to Stark et al. (2004b), are presented in Table 12.4.
Slope failure and stabilisation methods
Published in Sahadat Hossain, Sadik Khan, Golam Kibria, Sustainable Slope Stabilisation using Recycled Plastic Pins, 2017
Sahadat Hossain, Sadik Khan, Golam Kibria
Geofoam is a generic term for rigid cellular polystyrene, which is often used in geotechnical applications and has provided solutions worldwide for many difficult subsoils. The most common types of geofoam are expanded polystyrene (EPS) and extruded polystyrene (XPS). EPS is formed with low-density cellular plastic solids that have been expanded as lightweight, chemically stable, environmentally safe blocks. It generally behaves like an elastoplastic strain-hardening material. The unit weights of the material range from 0.7 to 1.8 pcf and it has compression strengths ranging between 13 and 18 psi.
Application: Geotechnical Sustainability
Published in Andrew Braham, Fundamentals of Sustainability in Civil Engineering, 2017
Another benefit of EPS geofoam is the consistency of the product. Fill materials, where earthen based or alternative materials, are often sensitive to moisture and variability of source material along with nonuniformity of construction practices and procedures even within the same project. However, EPS geofoam, being manufactured off-site, can be highly controlled and engineered. The density of EPS geofoam for fill is generally 1.0–2.0 lb/ft3 (16–32 kg/m3); however, density variation (called density gradients) up to 10% can exist due to the manufacturing process. During construction, settlements up to 1% strain are often specified. After construction is complete, postconstruction settlement no greater than 2% strain may be specified (Farnsworth and Bartlett, 2007). The dimensions of the blocks are based on the mold, which in turn affects the delivery to a job site and the block layout more than engineering properties (Stark et al., 2004). However, the standard dimension of an EPS geofoam block is currently ∼35 × 48 × 96 in (∼900 × 1200 × 2400 mm), but dependent on manufacturers (in 2016, there were approximately 150 across the United States according to the EPS Industry Alliance website). EPS geofoam is generally covered immediately since if the material is exposed to UV radiation for extended periods (on a year scale), it will yellow and become brittle. According to Stark et al., (2004), EPS geofoam is inherently nonbiodegradable, and will not dissolve, deteriorate, or change chemically. In addition, EPS geofoam is not harmful or hazardous, no harmful gases are emitted during production, and the material will not interact with the ground/ground water. There have been instances where insects have tunneled/nested in EPS foam, but this can be deterred with chemical additives. Caution must also be taken with flammability. Flammability is expressed in oxygen index (OI—minimum relative proportion of oxygen in gas mixture required to support continuous combustion, percent). At sea level, a material will burn freely if the OI is less than 21%. EPS geofoam has OI of 18%, so it is inherently flammable. However, a bromine additive is generally added, so the OI is increased to approximately 24%, which adds approximately 10% more to the base material cost.
Attenuation Potential of Geofoam as Cover Material in Cut and Cover Tunnels during Earthquakes
Published in Journal of Earthquake Engineering, 2022
Sadri Shadabi, Mansour Parvizi, Masoud Rabeti Moghadam, Emad Mohammad-Alizadeh Samani
Years of practical experience with polymeric geofoam have proved its ability to withstand vertical and lateral stresses when used in the construction of earthworks. Stability, durability and resistance to moisture and deterioration are known as superior characteristics of the geofoam (Ertugrul and Trandafir 2017). Reported applications of geofoam in geotechnical works include reduction of static lateral earth pressures on rigid and non-yielding retaining structures (Ertugrul and Trandafir 2012) and attenuation of seismic forces on retaining walls (Ertugrul and Trandafir 2012; Trandafir and Ertugrul 2011).
Sustainability assessment of EPS-geofoam in road construction: a case study
Published in International Journal of Sustainable Engineering, 2019
Dharmendra Kumar Srivastava, Amit Srivastava, Anil Kumar Misra, Vaishali Sahu
Construction of roads infrastructure has a very vital role in economic development of a country. Sometimes construction of road is needed over soft or loose soils (compressible soils) that are considered unsuitable for supporting additional or repeated loads. To tackle such problems, engineers/designers are required to explore the use of alternate materials which are suitable in such condition and do not affect the construction schedule of the project. EPS-geofoam has been found as suitable alternate materials of conventional earthen materials to protect from overloading to underlying soils as well as adjacent structures due to its light weight and high compressive resistance for supporting traffic loads. Use of EPS-geofoam in construction saves time as EPS-geofoam is easy to handle without any need for special equipment. Use of EPS-geofoam does not require time-consuming quality assurance/quality control (QA/QC) testing because it is an engineered product and it arrives on site after having undergone rigorous QA/QC testing. EPS-geofoam is produced in blocks that can be cut into various shapes and sizes and a range of compressive resistances to suit specific project needs. As an engineered product, it can be produced to obtain the required compressive resistance. Following are some of the features of geofoam that makes it favourable to civil engineering construction purposes: Geofoam is a cellular plastic material, also called ‘thermo-cole’, is a super light material which is available in the form of blocks or cellular honeycomb form. As per ASTM D 4439, geofoam can be defined as block or planar rigid cellular foamed polymeric used in geotechnical engineering applications.In geotechnical engineering, EPS-geofoam is being tried as an alternative to various soil fill applications where a lightweight material is required to reduce stresses on underlying soils or lateral pressure to retaining walls, abutments or foundations.When subsurface explorations reveal that a project’s underlying soils are soft or unstable, the EPS-geofoam may be utilised as specialised treatment options to allow completion of the desired final product.