Geofoam Blocks Research Articles

Geofoam Block in Soft Soil Embankment Applications: A Review

The major issues of building a road over soft soils are low bearing capacity and large settlements. The challenges of road construction on soft soils are enormous, so innovative and environmentally friendly methods are required. Geofoam is a type of lightweight infill material and was already used in Norway in road construction applications in 1972. Using Geofoam reduces compacted fill by 40%, less excavation required and less pulverization of native soil making this a time-saving and economically and environmentally viable solution. The purpose of Geofoam backfill is for lightweight backfilling, reducing soil pressure. Geofoam blocks can be used as a substitute for soft soil fill or as fill on top of soft soil as subgrade for pavement. This paper discusses the latest developments on the various applications of Geofoam blocks as backfill in soft soils presented based on information provided by the author.

Laboratory investigation and theoretical analysis of lateral pressure exerted by expansive soils on retaining walls with expanded polystyrene geofoam block upon water infiltration

The lateral pressure exerted by expansive soils on retaining walls constructed with expanded polystyrene geofoam blocks (EXRW-EPS), upon water infiltration to saturation, is crucial for designing these structures. In this study, model tests were employed to examine the behavior of EXRW-EPS subjected to water infiltration, with concurrent monitoring of deformation and lateral pressure. The results showed that the compressive deformation of the expanded polystyrene (EPS) geofoam block facilitated swelling deformations of the backfilled expansive soil, effectively mitigating the lateral pressure experienced by the retaining wall. Upon saturation of the backfilled expansive soil, the total lateral force on the wall decreased by approximately 44% by the EPS geofoam block with a density of 12 kg/m3. A practical method for predicting the lateral pressure on EXRW-EPS upon water infiltration to saturation was developed based on the relationship between the EPS geofoam block and the backfilled expansive soil. The reliability of this method was corroborated by the model test results. Additionally, the effects of the density and thickness of the EPS geofoam block on the lateral pressure of EXRW-EPS were analyzed using the prediction method.

Engineering performance of lightweight geomaterial influenced by EPS density and mix ratio

This paper highlights the engineering behavior of an expanded-polystyrene (EPS)-bead-based fly ash geomaterial (FAGM). The proposed geomaterial was prepared by blending EPS beads of different densities and fly ash contents with cement as a binding agent. The effects of three different EPS bead densities (25, 30 and 35 kg/m3), four EPS mix ratios (0.5–2.0%) and two cement contents (15 and 20%) on density, compressive strength at three different curing periods, 7, 28 and 90 days; and elasticity modulus were studied. It was concluded that the behavior of FAGM prepared with low-density and low-content EPS is analogous to that of FAGM prepared with high-density and high-content EPS. To evaluate the performance of FAGM as a lightweight and strong material, an empirical ratio of strength to density is defined. FAGM with low-density and high-content EPS can be used as an efficient lightweight filling material, whereas FAGM with high-density and low-content EPS can be used as a strong filling material. Moreover, the geomaterial, which is mainly formed from a freely available industrial byproduct, can be strongly used as a replacement for EPS geofoam blocks.

Engineering properties and sustainable applications of pond ash geomaterial incorporating expanded polystyrene beads

This study investigates the engineering behavior of a sustainable geomaterial called Pond Ash Geomaterial (PAGM), made by blending Expanded Polystyrene beads (EPS) with pond ash and cement as a binding agent. The effects of EPS density, beads content, and cement content on the density, compressive strength, and elasticity modulus of PAGM are analyzed. The results show that PAGM with low-density and low-content EPS can achieve similar properties to high-density and high-content EPS PAGM. Based on these findings, design charts are proposed that can facilitate the guidelines for the application of PAGM on-site. The study highlights the suitability of PAGM as a lightweight filling material that can reduce environmental impact and be a cost-effective alternative to EPS geofoam blocks. Predictive models are developed for determining the engineering characteristics of the PAGM. Overall, the use of PAGM as a building material has practical implications for sustainable construction practices, as it utilizes an industrial byproduct, reduces waste, and can be used in a range of applications.

Construction of geofoam block embankments atop existing transportation infrastructure

Expanded polystyrene (EPS) block (geofoam block) is a mature geotechnology for constructing highway embankments. In addition to preventing bearing capacity and settlement related stability problems for the embankments constructed on soft soil sites, geofoam blocks are also used to construct embankments atop existing infrastructure. Selecting geofoam technology for these applications not only prevents possible structural problems due to the lightweight nature of geofoam blocks but also eliminates costly remediation alternatives. The details of three well-documented and monitored different geofoam embankments constructed atop different existing infrastructures (buried pipeline, buried culvert and pile cap of drilled shafts for a deep excavation) are presented. The backgrounds of these projects, design considerations, construction and instrumentation details are discussed. The monitoring results were presented, and long-term performance predictions were evaluated. Numerical modeling effort was utilized to model the both short- and long-term behavior of geofoam embankments. Time-dependent behavior of the embankments under service loads was compared with numerical simulations. Constitutive modeling and related mechanical properties of geofoam blocks, which mimicked the long-term field behavior, as a function of geofoam density were proposed for future numerical modeling efforts.

Active earth pressure on non-yielding retaining walls with geofoam blocks and granular backfills

Geofoam blocks are typically used as buffer layers behind non-yielding retaining walls to reduce the lateral earth pressure. The interaction between the geofoam blocks and the backfills is essential for the determination of the earth pressure and thus the design of the geofoam blocks. In this study, two-dimensional model tests of aluminum rod mass as filling soils were conducted to study the lateral earth pressure acting on a non-yielding wall with geofoam blocks. The following observations were obtained: (i) the compression of the geofoam blocks increases linearly or bi-linearly along the wall height, depending on the stress level; (ii) a clear slip surface can be observed in the aluminum rod mass, which is consistent with the assumptions of the Coulomb’s active earth pressure theory. Considering the deformation of the geofoam blocks and the backfills, a series of equations were proposed for calculating the earth pressure on the non-yielding wall with geofoam blocks and granular backfills. The earth pressure calculated by the proposed equations agrees well with the experimental measurements.

Shear strength characteristics of interlocked EPS-block geofoam-sand interface

Translation of entire geofoam embankment at the bottom of geofoam block assemblage and bedding sand is a possible internal failure mode due to unbalanced hydrostatic forces. In addition, available shearing resistance along the bottom of geofoam block assemblage and bedding sand is an important design issue for internal seismic stability analysis. This study has focused on the methods to increase the interface shear resistance along the traditional flat surface geofoam block and bedding sand interface. In addition to traditional flat surface geofoam-sand interface, the effect of four different interlock configurations composed of geofoam blocks with one- and four-triangular and one- and four-square ledges were quantified by using direct shear tests. Two different densities (EPS19 and EPS29) and two different types of sand (Ottawa sand and Adapazari sand) were used. Therefore, the effects of geofoam stiffness, interface geometry, grain size and particle shape of the bedding sand on the interface stress-strain behavior was quantified. Manufacturing ledges along the traditional geofoam surface significantly improved the geofoam block-sand interface shear resistance. In addition, interrupting the failure plane with ledges changed the interface shear mechanism of the traditional flat surface geofoam block-bedding sand interface from purely frictional to frictional-cohesive behavior.

Applications of EPS Geo-foam and Geo-membranes in Construction Industry – Bridges, Embankments

This paper mainly concentrates on the uses and applications of EPS geo-foams and geo-membranes in construction industry like Bridges and Embankments over weak soil (compressible soils). If any external load is acting on weak soil, it will undergo settlement and the soil will be compressed. To overcome these settlements and compression of the weak soils, in this research we suggest EPS geo-foams. The EPS means “Expanded Poly Styrene”, it is a light weight material which is 1% weight of soil and it is less than 10% weight of other light weight materials and it is available in different densities. It has high compressive resistance and it reduces settlement of weak soil. It is generally used as a soil fill replacement material. If the soil contains any moisture content, the geo membrane acts like a water barrier for the geo-foam material. Geo-membrane is a thin continues polymeric sheets and it is a geo synthetic material, it is generally used in construction industry and geotechnical applications. If we place different types of densities of EPS geo-foam blocks and geo-membranes over weak soil in bridges and embankments, the soil behaviour is changing and attaining stability. Finally based upon the behaviour of weak soil we conclude that, at which density of the EPS blocks the soil attain more strength and how other strength parameters has been related to density by conducting the different tests.

EPS Geofoam Pavement Foundations Overlaid by Geocell-Reinforced Soil under Static Loading: Large-Scale Tests and Numerical Modeling

AbstractPavement foundations supported on expanded polystyrene (EPS) geofoam blocks are vulnerable to excessive deformation or even failure owing to truck passage during construction. To investigat...

Protecting buried pipelines using different shapes of geofoam blocks

Purpose. This research presents experimental modeling and numerical analysis on reducing stress and protecting buried pipelines using three arrangements techniques of expanded polystyrene (EPS) geofoam blocks: embankment, EPS block embracing the upper part of the pipe and EPS blocks as two posts and a beam. Methods. An experimental model consisted of steel tank with boundaries dimensions depending on the diameter of the pipe located at the center of it. The backfill on the pipe was made from sand and embedded EPS blocks with two techniques: EPS block embracing the upper part of the pipe and EPS blocks form two posts and a beam. Series of experiments were carried out using static loading on rigid steel plate to measure the pipe deformations and strains, as well as backfill surface displacement. The numerical analysis was used to simulate the experimental model using the finite element software program PLAXIS-3D. Findings. The results reveal that the most effective method which prevents stress on the buried flexible pipe was EPS post and beam system followed by EPS embracing the upper part of the pipe. The results obtained from the numerical analysis and the experiment demonstrate the same trend. The parametric study shows that EPS post and beam blocks model has higher surface displacement than embracing the upper part of the pipe model, which is more effective in case of high rigidity of the pipe. Originality. Reducing stress on buried pipes using different geofoam shapes to find which one is the optimum method. Practical implications. Two configurations of EPS geofoam blocks – EPS block embracing the upper part of the pipe and EPS blocks post and beam system - ensure successful stress reduction and protect buried pipes

Shear behavior of geocell-geofoam composite

In design, internal stability of EPS lightweight fills are provided either by applying load distributing mechanisms (thick pavements or concrete slabs) or using more strong lightweight material through denser EPS geofoam blocks. However, unit weight of the EPS geofoam is a limited parameter. As an attempt to improve the mechanical properties of EPS geofoam, geocell-geofoam composite (GGC) is introduced in this study. Geocell mattresses were infilled with solidified geofoam beads in the factory to fabricate GGC. The EPS geofoam and GGC samples were tested using a large-scale shear test apparatus of size measuring 1 m3. Results indicate that inclusion of the geocell leads to a considerable increase in the shear strength and a great decline in the compressibility of the geofoam. In comparison with EPS blocks, up to 72% rise in the shear strength and 67% decline in the vertical displacement were observed in GGC samples at the normal stress of 35 kPa. In addition, incorporation of the geocell was found to change the resisting mechanism of the EPS geofoam from cohesive to cohesive-frictional. While there was only 4.5% decline in the cohesion, the internal friction angle of the tested geofoam increased six-fold due to the involvement of the geocell.

Earth Pressure Distribution on Buried Pipes Installed with Geofoam Inclusion and Subjected to Cyclic Loading

Buried pipes and culverts installed under embankments supporting transport infrastructure are often designed to carry both static and cyclic loading. Earth pressures acting on these structures are affected by the installation conditions. The induced trench approach is used to reduce the contact pressure on rigid culvert’s walls under heavy embankments by utilizing the shear strength within the backfill. A compressible material, such as the EPS geofoam blocks, is generally placed above the buried structure and the overlying prism of soil is allowed to move downward. In this work, the distribution of the contact pressure on a pipe buried within granular material and experiencing cyclic loading is investigated. Results are presented at key locations on the pipe circumference and the changes in contact pressure during cyclic loading are examined. Results show that the installation of EPS geofoam block over the pipe resulted in overall enhanced performance of the soil–geofoam–pipe system with significant reduction in the measured radial pressure, particularly at the crown and invert locations. Less pronounced effect was found at the sides of the pipe. These results confirmed that the inclusion of EPS geofoam within the backfill material can significantly enhance the response of buried structures particularly for shallow-buried pipes under repeated loading.

Combining EPS geofoam with geocell to reduce buried pipe loads and trench surface rutting

This paper reports full scale experiments, under simulated heavy traffic, of geocell and EPS (expanded polystyrene) geofoam block inclusions to mitigate the pressure on, and deformation of, shallow buried, high density polyethylene (HDPE) flexible pipes while limiting surface settlement of the backfilled trench. Geocell of two pocket sizes and EPS of different widths and thickness are used. Soil surface settlement, pipe deformation and transferred pressure onto the pipe are evaluated under repeated loading. The results show that using EPS may sometimes lead to larger surface settlements but can alleviate pressure onto the pipe and, consequentially, result in lower pipe deformations. This benefit is enhanced by the use of geocell reinforcement, which not only significantly opposes any EPS-induced increase in soil surface settlement, but further reduces the pressure on the pipe and its deformation to within allowable limits. For example, by using EPS geofoam with width 0.3 times, and thickness 1.5 times, pipe diameter simultaneously with geocell reinforcement with a pocket size 110 × 110 mm2 soil surface settlement, pipe deformation and transferred pressure around a shallow pipe were respectively, 0.60, 0.52 and 0.46 times those obtained in the fully unreinforced buried pipe system. This would represent a desirable and allowable arrangement.

Geofoam blocks to protect buried pipelines subjected to strike-slip fault rupture

This paper proposes using geofoam blocks to improve the safety of buried steel pipelines under permanent ground deformation due to strike-slip fault rupture. Since these geofoam blocks are deformable, they can compress during fault rupture and thus reduce the pressure imposed on the pipeline by the surrounding soil. This means that the pipe can sustain a higher level of tectonic deformations. For the pipeline system adopted in this study, the geofoam blocks consist of two 1 m thick blocks at each side and another on the top of the pipeline. The effectiveness of this configuration is then assessed in comparison to the conventional buried pipeline by three dimensional numerical simulations that consider the interaction between soil and structure and the impact of critical parameters such as the pipeline-fault trace crossing angle, geofoam blocks thickness and the internal pressure of the pipeline. The results indicated that the geofoam blocks reduced the axial tensile strain of non-pressurised pipeline from the unacceptable 4.16% to the safe level of 0.75% when the crossing angle was 135°. In addition, geofoam blocks successfully decreased the maximum ovalisation parameter and compressive strain of the non-pressurised pipeline from 0.237 and −25.8% to 0.065 and −0.47%, respectively when the crossing angle was 65°.

An alternate arrangement of geofoam blocks and air pocket to mitigate confined blast induced vibration

ABSTRACT The present study focuses on the performance of intermittent geofoam in-filled (IF) trench as a passive vibration screening when a reinforced concrete (RC) lining tunnel is subjected to internal blast load. The blast analysis of lined tunnel is performed using a three dimensional non-linear finite element (FE) method. The coupled Eulerian-Lagrangian (CEL) analysis tool has been employed in the FE software ABAQUS/Explicit for the purpose of this study. The explosive trinitrotoluene (TNT) has been modelled using Eulerian elements as the blast source in the tunnel. The IF has been installed at the far field from the source to protect the vibration sensitive buildings and equipment in that region. The parameter, which controls the design of intermittent geofoam trench, is its geometric parameters (width, depth, location). EPS geofoam density and soil Poisson’s ratio have been considered to investigate the performance. In addition to IF, another newly proposed technique named staggered intermittent geofoam (SIF) has also been investigated in the present study. The results of simulation show that both IF and SIF can be a very good passive vibration screening technique subjected to blast sources.

Experimental evaluation of an expanded polystyrene (EPS) block-geogrid system to protect buried pipes

This study presents the results of experimental tests carried on buried uPVC (unplasticized polyvinyl chloride) pipes with an external diameter of 160 mm. The behavior of buried pipes in unreinforced and reinforced trenches by a single layer of HDPE (high-density polyethylene) geogrid and expanded polystyrene (EPS) geofoam block were investigated. To simulate vehicle wheel loadings, 500 cycles of repeated load respectively with an amplitude and frequency of 450 kPa and 0.33 Hz was applied to a loading plate placed over the trench surface. Pipe behavior under cyclic loadings were assessed using vertical diameter strain measurements, circumferential strains and pressures at the crown and springline. Additionally, settlement at the soil surface was measured throughout testing. The testing program is aimed at evaluating the role of different parameters influencing pipe behavior, such as embedded depth of the pipe, implementation of the EPS block and geogrid layer simultaneously and separately, and density, width and thickness of the EPS blocks. The results illustrate that the rate of changes in the pipe circumferential strain, vertical diameter strain and soil surface settlement, which increase rapidly in initial loading cycles, decreased as loading progressed. Based on the results, the density, width and thickness of implemented EPS blocks have an impact role in improving the behavior of buried pipes. The use of geogrid reinforcement with an EPS block with density of 30 kg/m3, thickness of 60 mm and width of 1.5 times the pipe diameter showed the most benefit when balancing vertical diameter strain, pipe crown strain, and soil surface settlement.

Application of EPS Geofoam to a Soil–Steel Bridge to Reduce Seismic Excitations

There have only been a limited number of analyses of soil–steel bridges under seismic and anthropogenic (rockburst) excitations. Rockbursts are phenomena similar to low-intensity natural earthquakes. They can be observed in Poland (Upper and Lower Silesia) as well as in many parts of the world where coal and gas are mined. The influence of rockbursts and natural earthquakes on soil–steel bridges should be investigated because the ground motions caused by these two kinds of excitations differ. In the present paper, a non-linear analysis of a soil–steel bridge was carried out. Expanded polystyrene (EPS) geofoam blocks were used in a numerical model of the soil–steel bridge to buffer the seismic wave induced by a rockburst (coming from a coal mine) as well as a natural earthquake (El Centro record). The analyzed soil–steel bridge had two closed pipe arches in its cross-section. The span of the shells was 4.40 m and the height of the shells was 2.80 m. The numerical analysis was conducted using the DIANA program based on the finite element method (FEM). The paper presents the FEM results of a 3D numerical study of a soil–steel bridge both with and without the application of the EPS geofoam under seismic excitations. The obtained results can be interesting to bridge engineers and scientists dealing with the design and analysis of bridges situated in seismic and mining areas.

Response of pavement foundations incorporating both geocells and expanded polystyrene (EPS) geofoam

The suitability of geocell reinforcement in reducing rut depth, surface settlements and/or pavement cracks during service life of the pavements supported on expanded polystyrene (EPS) geofoam blocks is studied using a series of large-scale cyclic plate load tests plus a number of simplified numerical simulations. It was found that the improvement due to provision of geocell constantly increases as the load cycles increase. The rut depths at the pavement surface significantly decrease due to the increased lateral resistance provided by the geocell in the overlying soil layer, and this compensates the lower competency of the underlying EPS geofoam blocks. The efficiency of geocell reinforcement depends on the amplitude of applied pressure: increasing the amplitude of cyclic pressure increasingly exploits the benefits of the geocell reinforcement. During cyclic loading application, geocells can reduce settlement of the pavement surface by up to 41% compared to an unreinforced case – with even greater reduction as the load cycles increase. Employment of geocell reinforcement substantially decreases the rate of increase in the surface settlement during load repetitions. When very low density EPS geofoam (EPS 10) is used, even though accompanied with overlying reinforced soil of 600 mm thickness, the pavement is incapable of tolerating large cyclic pressures (e.g. 550 kPa). In comparison with the unreinforced case, the resilient modulus is increased by geocell reinforcement by 25%, 34% and 53% for overlying soil thicknesses of 600, 500 and 400 mm, respectively. The improvement due to geocell reinforcement was most pronounced when thinner soil layer was used. The verified three-dimensional numerical modelings assisted in further insight regarding the mechanisms involved. The improvement factors obtained in this study allow a designer to choose appropriate values for a geocell reinforced pavement foundation on EPS geofoam.

Stabilizing soft clay using geo-foam beads and cement bypass dust

Soft clays are usually classified according to their undrained shear strength, Su. Values of Su less than 12.5 kPa are associated with very soft clays. In addition to their low shear strength, soft clays exhibit high compressibility upon loading. Therefore, soft clays are considered to be problematic for foundation purposes. Geo-foam is an industrial material that is characterized by a very low unit weight (20 kg/m3 on average) compared to that of the soil. The density of expanded polystyrene (EPS) ranges from 1.0% to 2.5%, which results in a compressive strength ranging between 70 kPa and 140 kPa and an elastic modulus ranging between 5 MPa and 12 MPa. EPS geo-foam blocks are used in a wide range of geotechnical applications as a lightweight fill material.The main objective of this study was to investigate the geotechnical properties of soft clays containing geo-foam beads and cement bypass dust (CBPD). We also investigated the viability of preparing low-strength excavatable fill mixtures. To study the effect of (geo-foam beads + CBPD)/soft clay on the fluid-state and hardened properties of new fill, we conducted experiments on two groups of mixtures (A&B). Each mixture contained different ratios of geo-foam beads and CBPD so that we could study the effect of the additive on the flow consistency, dry unit weight, unconfined compressive strength, and shear strength of the mixture. The test results showed that the unconfined compressive strength of the studied mixtures without geo-foam ranged from 271.8 kPa to 1405.14 kPa at CBPD concentrations between 3.88% and 18.63%. The cohesion values for the group containing geo-foam ranged from 50 kPa to 20 kPa at geo-foam percentages between 0.32% and 1.35%. The friction angle of the group containing geo-foam ranged from 10 kPa to 22 kPa at CBPD percentages between 0.32% and 1.35%. Cement bypass dust can be successfully used to process self-compacting, self-leveling, excavatable and flowable fill material.

On the role of geofoam density on the interface shear behavior of composite geosystems

Expanded polystyrene (EPS) geofoam has been increasingly used in geotechnical engineering applications to replace conventional backfill material or to reduce earth pressure on retaining and buried structures. In most of these applications, geofoam blocks are installed in direct contact with different construction material (soil, concrete, steel, wood, etc.). This results in a composite system that is subjected to loading in both the normal and shear directions. Therefore, successful analysis and design of these composite structures require a detailed knowledge of interface strength characteristics of geofoam under a combination of normal and shear stresses. In the current research, an attempt has been made to study the interface shear characteristics of geofoam with selected materials, including concrete, wood and steel. Three different geofoam densities namely, 15, 22 and 39 kg/m3 were used in this study. A series of direct shear tests (DST) was conducted with a shear box of dimension 100 mm × 100 mm × 50 mm under three different normal stresses 18, 36 and 54 kPa. Test results revealed that geofoam density and applied normal stress have significant effects on the vertical compression and interface strength properties (i.e. adhesion and friction angle) of the investigated geosystem. Surface roughness was found to play a significant role in the shear resistance at the contact. Geofoam–concrete interface showed maximum strength as compared to wood and steel materials. Care should be exercised when placing geofoam against steel or wood surfaces as the mobilized friction angle is generally small and sliding may develop depending on the applied normal stress level.