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Über dieses Buch

These proceedings of the EPS 2018: 5th International Conference on Geofoam Blocks in Construction Applications, held in Kyrenia, Northern Cyprus on May 9 to 11, 2018, present a collection of contributions on the state-of-the-art of research and applications relating to geofoam. Geofoam researchers, consultants, molders, contractors and practitioners from all around the globe discuss the recent developments and future trends of expanded polystyrene (EPS)-block geofoam technology and its construction applications. EPS’18 contributes to the development of geofoam applications, following on from successful conferences in Oslo (1985), Tokyo (1996), Salt Lake City (2001) and Oslo (2011). The book discusses topics including, but not limited to, current use of geofoam, design specifications, applications, new concepts, material properties, modeling and specific topics in geofoam blocks in construction applications.

Inhaltsverzeichnis

Frontmatter

Key Note, Geofoam Blocks in Civil Engineering Applications

Frontmatter

Geofoam Blocks in Civil Engineering Applications

In Norway the use of Geofoam blocks in road construction applications started in 1972. Excessive settlements of a road embankment adjoining a bridge abutment founded on piles to firm ground was then successfully halted by replacing a 1 m layer of road aggregate with blocks of Expanded Polystyrene (EPS). Boards of EPS had previously been successfully tested in road structures over several years in a major research project related to Frost Action in Soils. The use of Geofoam blocks for lightweight fill purposes, reduced earth pressure and several other applications for a variety of Civil Engineering purposes, has since been adopted and further developed in many countries worldwide. In this article the state of the art regarding various applications of Geofoam blocks are shown based on available information supplied by the authors.

Roald Aabøe, Steven Floyd Bartlett, Milan Duškov, Tor Erik Frydenlund, Jnanendra Nath Mandal, Dawit Negussey, Abdullah Tolga Özer, Hideki Tsukamoto, Jan Vaslestad

Construction Applications

Frontmatter

Dutch A4all Tramway EPS Embankment with Vertical Sides

New section of the motorway A4 in the urban area between Vlaardingen and Schiedam is constructed in a concrete tunnel realized on ground level and covered by soil for a minimal environment impact. This new A4 route crossed the existing tram tracks. The construction of the tunnel with belonging embankments resulted in a 6 m high position of the tramway overpass. Despite low bearing capacity of the local subsoil the strict settlement requirements were valid for the ≥180 m long embankments on both sides of the motorway tunnel. Additionally complicating aspect was the realization period of only twelve weeks. Also the inconvenience to local residents living in surrounding large apartment buildings had to be minimized. Therefore, almost entire embankment length has been realized using 22,000 m3 EPS geofoam blocks. Applied embankment cross section design with vertical sides without slopes made it possible to realise the cross sections in two phases. Firstly, the northern cross section half with a pavement structure at the top was completed. Otherwise the original tram line could not stay in service during time of construction and the deadline of twelve weeks could not be met. These twelve weeks were necessary to complete the embankment cross section with the southern half. The new tram tracks are assembled at the top of it. The applied design approach for a phased realization of the 20 m wide lightweight embankment cross section is unique for Dutch engineering practice.

Milan Duškov, Johan de Jongh

Geofoam Eps Used in Bridge Abutment, E18 Farris Bridge

Norwegian Public Roads Administration is building Farris Bridge on European road 18 in Larvik. The total length of the Farris Bridge is 570 m. EPS Geofoam is used in the bridge abutments. Ordinary stone embankments as bridge abutments would have created large settlements. Use of EPS Geofoam is also a very economical alternative compared to a piled embankment inside the abutment. The total volume of EPS in the bridge abutments is 11,000 m3, with 4000 m3 in abutment east and 7000 m3 in abutment west. The quality of EPS used is mainly with strength 180 kPa. In some highly stressed zones of the embankments, the strength of EPS is 300 kPa. Result of testing for quality control is included in the article.

Jan Vaslestad, Jørn Einar Liveroed, Tseday Damtew, Staale Singstad, Dag Loevstad

EPS Geofoam Used in E16 Sandvika–Wøyen

The Norwegian Public Roads Administration is building a new four lane motorway between Sandvika and Wøyen. The construction involves development of new intersections with a planned terrain elevation of up to 7 m, in areas with soft clay. This is challenging with respect to ground stability and settlements. Especially since the existing road, that was built in the 1980s, has already experienced settlements of 1.5–2 m. The designed solution has therefore involved extensive use of EPS in combination with granulated foam glass. In total 3 EPS-fill will be constructed during the project and one of them is placed on lime/cement reinforced ground. The most comprehensive fill will have a volume of approx. 11,000 and 27,000 m3 for the project in total. The compressive strength of the EPS is 100 kPa.

Ermias Hailu Mijena

First Geofoam Roadway Embankment Application in Turkey

The first geofoam block roadway embankment application in Turkey was completed in April 2017 in Acibadem, Istanbul. Geofoam technology was selected to construct the roadway embankment on a site where two 2.2 m diameter water mains are located 3.8–5.6 m below the foundation of the embankment. Geofoam blocks not only prevented the relocation cost of this infrastructure in a very complex urban setting in terms of buried utility corridors, but also prevented possible structural damage to the mains if conventional earth fill was used to construct the embankment. In addition, water service was not interrupted during the construction. The project background, design considerations, and construction sequence is presented. In order to monitor the performance of the embankment, a field instrumentation array comprised of extensometers was installed in the foundation soil, bedding sand, geofoam block assemblage, and under the load distribution slab. Instrumentation details and monitoring results over a period of ten months is discussed, and long-term performance projections were evaluated using short-term performance data.

Abdullah Tolga Özer, Emre Akınay

Dutch A76 Highway Widening Using EPS Embankment with a Vertical Side

This article concerns the A76 highway widening (near the Kerensheide junction) using a lightweight fill with a vertical embankment. The A76 highway section (widened from 2 × 2 to 2 × 4 lanes) lies 4 m above a truncated slope and is situated between two concrete structures. The design of the fill should not decrease the stability of the current slope (with a high retaining wall at the toe of the slope) and had simultaneously to create sufficient space for the planned highway widening. In addition, the fill should have no influence on a crossing high-pressure gas pipe. The daily traffic load amounts to about 8600 trucks. These complex conditions have led to an extension of the highway cross section realized with EPS blocks with a vertical embankment; a first in the Dutch engineering practice. The EPS geofoam blocks were piled up 4 m above ground level and 2 m bellow the slope line. The performed parameter study confirmed that the friction between the EPS-blocks in combination with a low Poison’s ratio is sufficient to provide stability. No side support is needed to secure the slope stability after the completion of the highway A76 widening. Although the applied design method requires specific expertise, this design offers multiple advantages such as saving both space and costs, stability increase and a very short construction time.

Milan Duškov, Martin den Uil, Michaël Fütterer

Dutch N201 Road Embankment with EPS Geofoam

The new section of the provincial road N201 between the Amstel aqueduct (founded on piles) and a junction near Uithoorn characterizes a 200 m long lightweight road embankment which is necessary because of local settlement sensible subsoil. In total 14,000 m3 EPS is built-in in this up to 4.1 m high embankment despite applied preloading and partial weak subsoil replacement. In the scope of the designing process the subsoil parameters for the Plaxis models were adjusted on the basis of the monitoring results. In this way the road embankment design was optimized regarding both the structural and the settlement behaviour. However, visual inspections carried out by the supervision team of the province North Holland in combination with quality controls in laboratories during the construction process pointed out serious shortcomings of delivered materials and the construction work. Therefore the design had to be adjusted twice to guarantee the design life of the lightweight road structure and to minimize the settlements. Specialized technical assistance was necessary to ensure timely and effective checks needed and to prescribe appropriate compensatory measures. Obviously, contractors often underestimate the consequences of the use of EPS in engineering practice and the differences between geofoam blocks and other conventional embankment materials.

Milan Duškov, Wim Erkelens

Post-use Examination of EPS Block Characteristics: Finnish Case Histories

Since its introduction as a lightweight fill in the 1980s, EPS has been used in a number of test highway embankments across Finland. This paper presents the experiences in using EPS blocks as structural element in two lightweight road/highway embankment sites in Finland. These embankments were built on soft soil deposits and therefore, the EPS was introduced to improve the bearing capacity of the ground and to subsequently reduce settlement. Once the use was ceased, the EPS blocks were retrieved from the embankments and tested for their water absorption characteristics and mechanical properties. These properties were then compared with their original properties and other relevant local standards in order to assess their potential reusability. The test results revealed that the retrieved EPS blocks still fulfilled the mechanical requirements of the Finnish guidelines after being in contact with the ground for over 14 years. One of the primary goals of this study was to increase the competitiveness of EPS in civil engineering applications and to encourage the reuse of EPS in other civil engineering applications in Finland. The information presented in this paper is intended to provide an understanding of the performance of EPS blocks in lightweight fill applications. It may also assist engineers in design and construction methods of similar EPS applications, and the potential reusability of such used EPS blocks in various other applications.

Gowthaman Sinnathamby, Leena Korkiala-Tanttu, Henry Gustavsson

Analysis of Crack and Differential Settlement on Pavement in EPS After Highway Opening

The lateral movement of abutment has induced significant problems in the terms of either construction and management since 1990 in South Korea. The research related to this issue has been also paid wide attention. In order to overcome these problems, modified lateral float, sand compaction method (SCP), and pile-slab method have been developed. Especially, the EPS was extensively used in the soft ground to either prevent or mitigate the lateral movement. Although th EPS is surely effective on reducing lateral movement of abutment and load during the construction, cracks and deterioration may be found on the pavement in the EPS section after opening the road. In this study, structural performance test and eye investigation of drilling cores from the site where the EPS was widely applied were conducted and analyzed.

Yongchai Chang, Nagyoung Kim

Load Reduction on Buried Rigid Culverts, Instrumented Case Histories and Numerical Modeling

Three instrumented full-scale tests using geofoam (expanded polystyrene) for load reduction on buried rigid culverts are described. The culverts were built and instrumented during the period 1988–1992. The method involves installing a compressible inclusion (EPS Geofoam) above rigid culverts in order to reduce the vertical earth pressure. The first instrumented culvert is a concrete pipe with diameter 1.95 m beneath a 14 m high rock-fill embankment. The second full-scale test is a concrete pipe with diameter 1.71 m beneath a 15 m high rock-fill embankment. The third instrumented structure is a concrete box culvert with width 2.0 m beneath 11 m of silty clay. The long-term observations of earth pressure and deformation are presented, and compared with a simplified design method and finite element modelling using the finite element program, Plaxis 2D for the box culvert. The instrumentation consisted of hydraulic earth pressure cells, deformation and temperature measurements. The use of geofoam effectively reduces the vertical earth pressure, and long-term observations shows that the earth pressure is reduced to less than 30% of the calculated overburden in case of granular fill. Whereas the earth pressure is reduced to less than 50% of the calculated overburden in case of silty clay fill. The long term observations of earth pressure and deformation for more than 25 years show that the method using geofoam is stable over time. The last measurements were taken in 2015. The results from the numerical modelling are in agreement with the field measurements.

Jan Vaslestad, Murad Sani Sayd

Improving the Behavior of Buried HDPE Pipe by Using EPS Geofoam

A buried thermoplastic pipe installed with conventional method deflects vertically downwards under soil load. Because the displacement of the pipe crown is more than that of the sidefill soil, differential settlements in the soil medium above the pipe crown level take place. Differential settlements lead to the development of a mechanism called “positive soil arching” within the soil medium and, consequently, a vertical stress smaller than the geostatic stress acts on the crown of the thermoplastic pipe. The degree of arching depends on the magnitude of the differential settlements. Therefore, the degree of arching can be increased by installing a zone or zones of a compressible material, which will increase the magnitude of the differential settlements, around the thermoplastic pipe when the pipe is being installed. The increase in the degree of arching will provide less vertical stress on the pipe crown and an improved pipe behavior. This paper presents a part of the findings obtained from true-scale laboratory model tests and finite element analysis which were performed to investigate the effects of compressible zone application on buried HDPE pipe behavior. EPS Geofoam with 10 kg/m3 nominal density was used as the compressible material. Compressible zone with proposed geometry provided a reduction in vertical pipe deflection of up to 89%, in horizontal pipe deflection of up to 96% and in vertical stress on the pipe crown of up to 77%. Finite element analysis showed that the compressible zone provided relatively very small bending moments and almost a uniform bending moment distribution around the pipe. Under 200 kPa surcharge stress, a reduction in the maximum bending moment around the pipe of 78% was provided.

Emre Akınay, Havvanur Kılıç

Material Properties and Modeling

Frontmatter

Creep Behavior of Recycled-Content Expanded Polystyrene Geofoam Under Compressive Loading

This paper presents conventional creep test results for 0, 15 and 30% recycled-content expanded polystyrene (EPS)-block geofoam. The tests were performed on 50-mm (2-in.) cubical specimens with a nominal density of 21.6 kg/m3 under different stress levels for more than 9 months. It is concluded that the creep strain of recycled-content EPS geofoam increases with time and stress level in a manner similar to virgin EPS geofoam. As with virgin EPS geofoam, the elastic-limit stress appears to be a threshold stress level for creep strain development in recycled-content EPS geofoam.

Chuanqi Wang, David Arellano, Roger Meier

The Influence of Strain Rate on the Stress-Strain Behavior of EPS Geofoam

Modulus, yield and strength properties of EPS geofoam that are reported in standards and specifications vary by density and are typically derived from testing small size samples at 10% per minute strain rate. Such values are augmented by creep test data from published sources in design considerations. Average loading rates during construction and sustained dead loads in post construction induce much slower strain rates. Live loads from truck traffic and extreme events such as earthquakes occur at faster strain rates. The margin of higher strengths that could be justifiably allowed for extreme events of short duration has not been established. This investigation examined the effects of strain rates on moduli and strengths for different densities of EPS geofoam.

Djiba Kaké, Engda Kassahun Temesgen, Dawit Negussey

Evaluation of Interface Shear Strength Between Interlocked Geofoam Blocks and Precast Concrete

The separation layer between the top of an expanded polystyrene (EPS) block (geofoam block) roadway embankment assemblage and the pavement system is usually comprised of a reinforced Portland cement concrete (PCC) slab. The prevailing construction technology is the cast-in-place method. However, there is a growing consensus that the current state of practice may represent a significant cost, especially to project schedules. As an alternative, this study proposes the use of precast concrete panels. In order to guide design engineers, interface friction properties of traditional flat-surfaced geofoam blocks with a minimum density of 18.4 kg/m3 and precast concrete panels were quantified by using direct shear testing. In addition, four different types of interlock configurations (geofoam blocks with one- and four-square ledges and geofoam blocks with one- and four-triangle ledges) were used to investigate the effects of interlocked geometry and number of ledges in the shear plane between interlocked geofoam block and precast concrete. The interface friction behavior of precast concrete and traditional flat-surfaced geofoam block was found to be purely frictional. The interface friction angle of precast concrete and interlocked geofoam blocks was found to be higher than that of traditional geofoam blocks. Implementing an interlocked configuration, which interrupts the continuous shear plane with ledges, changes the interface friction mechanism of precast concrete and geofoam block from purely frictional to frictional-adhesional. Independent of the geometry of the ledges, adhesion was developed in addition to interface friction. Both adhesion and interface friction angle increased with number of ledges.

Abdullah Tolga Özer

California Bearing Ratio (CBR) Behaviors of EPS Geofoam: Experimental and Numerical Studies

Expanded Polystyrene (EPS) geofoam is ultra-lightweight, closed cell, rigid, plastic foam. It can be used for lightweight fill, compressible inclusion, thermal insulation, drainage and so forth. An experimental study was carried out to investigate the California bearing ratio (CBR) behavior of EPS geofoam. Three different densities of EPS geofoam 12, 15 and 20 kg/m3, and six different piston sizes (0.75D, D, 1.2D, 2D, 2.3D and 2.6D) where D is diameter of standard piston were used for standard CBR sample size. Moreover, in the present study CBR of EPS geofoam is investigate at dry and submerged in water conditions. The effect of piston diameter and density on the CBR values of EPS geofoam were investigated. The study revealed that increase of density of EPS geofoam resulted in an appreciable increase in the CBR value. The CBR test results were found to be 0.87, 1.67, and 1.86% for 12, 15 and 20 kg/m3 densities of EPS geofoam respectively at 2.5 mm penetration with standard piston size. The test result shows that the CBR value increased with an increase in density of EPS geofoam, however, the effects of CBR values were not more pronounced between dry and wet test conditions. The benefit of increasing or decreasing piston diameters beyond 50 mm does not improve the CBR value appreciably. An increase in density is more effective than an increase in piston diameter in improving the CBR value of the EPS geofoam. It is observed that the CBR value of EPS geofoam is very less and equivalent with clay soils. The density of EPS geofoam used for the construction of pavements should be more than 15 kg/m3 concerns related to the quality and the durability of the material. Finite element analysis was also carried out using PLAXIS 2D software to validate with experimental results. A reasonable agreement was observed between the numerical and experimental studies on pressure-displacement response.

Yebeltal Zerie Beju, Jnanendra Nath Mandal

Non Destructive Testing for EPS Geofoam Quality Assurance

Non Destructive testing (NDT) was used to check the quality of EPS geofoam blocks produced at different manufacturing plants. Strength and deformation parameters for design and construction are dependent on the quality of specified geofoam grades delivered on site. Ultra sound P wave velocities through EPS blocks were measured to obtain estimates of Young’s moduli for different densities produced at four molding plants. The moduli values derived from NDT were compared with previously reported results. Differences between P wave velocities and moduli for blocks formed with virgin material and blocks that contain recycled content were examined. The results indicate NDT is a versatile and more practical method for onsite quality assurance monitoring.

Engda Kassahun Temesgen, Luke Andrews, Dawit Negussey

Evaluation of Interface Shear Strength Between Interlocked Geofoam Blocks and Cast-in-Place Concrete

Expanded polystyrene (EPS) block (geofoam block) roadway embankment typically involves the construction of cast-in-place reinforced Portland cement concrete (PCC) slab as a traffic load distribution layer since it reduces live load stresses and also provides lateral confinement of the overlying unbound pavement layers. Therefore, in addition to the geofoam block to geofoam block and geofoam block to bedding sand, interface properties of geofoam block to cast-in-place concrete slab should also be investigated for the stability calculations regarding transitional sliding failure mode. In order to enhance the traditional geofoam block to cast-in-place concrete interface shear strength, previously introduced interlocked geofoam block concept has been utilized. Flat-surfaced traditional geofoam blocks were trimmed by a hot-wire to form interlocked geofoam blocks with ledges along their contact surface with the cast-in-place concrete. EPS19 with a minimum density of 18.4 kg/m3 was used in the experimental program. Four different types of interlock configurations (blocks with one- and four-square ledges and blocks with one- and four-triangle ledges) were used to investigate the effect of interlocked geometry and number of ledges in the shear plane. In addition, interface friction properties of traditional geofoam block and cast-in-place concrete surface was also quantified to highlight the improvement provided by the interlocking mechanism. The adhesion bond between traditional geofoam blocks and cast-in-place concrete was close to that of internal shear strength of geofoam blocks. Regardless of the shape, the interface adhesion bond was slightly improved by the number of ledges when compared to that of traditional geofoam and cast-in-place concrete.

Abdullah Tolga Özer, Özgür Ekincioğlu

Stress-Strain Behavior of EPS Geofoam with Multiple Grades by Using FlexiForce Sensors

Design and construction of geotechnical projects with EPS geofoam can involve consideration of interactions between structures, surrounding soils and geofoam blocks. Within large volume installations of geofoam blocks there can be unintended variability in block densities. Such conditions can lead to non-uniformities in stress distribution and development of uneven deformations. This study examines the effects of mixed use of geofoam density grades on stress-strain behavior in laboratory test settings. Interface loads at both geofoam to rigid plate and geofoam to geofoam mating surfaces were observed with FlexiForce sensors. Both uniform low and high density configurations were tested. Effects of mixing densities were also examined for both one and two layer block configurations.

Chen Liu, Dawit Negussey

Behavior of Expanded Poly Styrene (EPS) with Experimental and Numerical Methods

Using EPS in highways projects as subgrade material requires a substantial understanding of its behavior when subjected to static and cyclic loadings. Several research examples are available up to now regarding this issue, however, the concepts for the latter seems to have been paid less attention due to its complexity and time consuming nature. In an attempt to overcome the shortcomings, several test have been performed to determine the effect of static and cyclic loading on the performance of EPS geofoam. A simple numerical method is also proposed to simulate EPS behavior under cyclic loading. Further research is needed to derive more accurate results.

S. N. Moghaddas Tafreshi, S. M. Amin Ghotbi Siabil

Effects of Installation of Different Density Geofoam and Continuous Vertical Gaps

The mechanical properties of EPS geofoam vary with density. Usually, only one density or grade of EPS geofoam is specified per project. To maximize performance while reducing costs, higher density or grade EPS geofoam blocks have been specified for the top layers of fills in a few cases. The consistent best practices in EPS geofoam block installation have been: (a) not to install blocks of different densities in the same layer; (b) not to place blocks of lower density above higher density blocks; and (c) to stagger joints between blocks in successive layers so as to prevent continuity of inter-block vertical gaps. In practice, either by inadvertent misplacement or due to lax quality assurance and installation control, one or more of these three conditions can be violated. This investigation examined the effects of mixed densities and continuous vertical gaps between block layers. Groups of EPS block samples of the same density and also of mixed densities were tested with either staggered or continuous joints. The laboratory tests were simulated in computer models. The deformed shapes and dimensions indicated by the computer simulations were compared with the observed shapes and dimensions of the laboratory tests.

Chen Liu, Dawit Negussey

Effect of Using EPS Geofoam on Deformation Behavior of Square Footings on Clay Subjected to Static and Dynamic Loads: Experimental Study

The recent and continuous industrial development at Port-Said necessitates many factories and gas plants to be constructed on its thick graduated clay soil. Accordingly, suitable foundation systems are to be developed to resist the expected dynamic effects and vibrations of the heavy machinery and rotating masses utilized for such activities. Expanded Polystyrene (EPS) Geofoam was introduced as an efficient dynamic damper and lightweight solution for many geotechnical problems. In this research, the effect of the static loads in machinery shutdown state and the dynamic loads in working state on the settlement behavior of a square footing resting on Port-Said clay is studied experimentally, both in the presence and absence of EPS. The results showed that the use of EPS can considerably reduce the maximum settlement under machine foundation.

M. El. Gendy, I. El. Araby, W. El. Kamash, E. Sallam, A. El. Labban

Mechanical Properties of EPS Geofoam Under Various Loading Conditions

This study presents experimental studies on EPS geofoam using cyclic uniaxial compression (CUC), accelerated creep and pseudo-long-term tests. For all experiments 100 mm cube geofoam samples of 15 kg/m3 density (EPS15) are used. Servo-hydraulic actuator and temperature regulated water chamber (TRWC) are used. CUC tests are performed at two loading frequencies 0.5 and 3 Hz, R values of 0.4, 0.6, 0.8, 1 and 1.2 and 5000 loading cycles. Term ‘R’ defined as ratio of combined axial static and cyclic stress component to the yield strength of geofoam. To understand creep behavior of geofoam Time temperature stress superposition (TTSS) accelerated creep testing method is adopted. Master creep curve is developed for a designed strength of 20% compressive strength (σ c ) and reference temperature of 29 °C. From CUC tests it is observed that effect of number of cycles is insignificant on secant modulus (E dyn ) compared to R and loading frequencies. Also, Poisson’s ratio (υ) is observed to vary from positive to negative, and it majorly depends on R values and number of cycles. From TTSS method 2.12% compressive creep (CC) strain is observed at 100 years for EPS15 geofoam. Pseudo-long-term tests are performed at various CC intervals and it is noted that Young’s modulus (E) decreases with increase in CC. E, compressive strength and yield strength of CC sustained samples are decreased from that of initial or non-CC sustained samples. Moreover, Young’s modulus of geofoam reduces with time.

Vinil Kumar Gade, Satyanarayana Murty Dasaka

New Concepts and Special Topics

Frontmatter

Bridge Foundations Supported by EPS Geofoam Embankments on Soft Soil

EPS geofoam can be used to support highway bridge structures without the aid of deep foundations. The development of this technology is important to accelerate construction on soft compressible soil. EPS geofoam allows for the rapid construction of bridge foundations on such soils without the time and cost involved in installing traditional foundations. Because EPS geofoam is an extremely light weight fill, it can be used to avoid settlement impacts at bridge approaches. In Norway, bridges have been directly supported by EPS geofoam. Norwegian Public Roads Administration has pioneered this application for a few bridges underlain by soft, clayey deposit where the bridge structure rests solely on EPS geofoam blocks. Investigating bridge foundations supported by EPS geofoam embankments is a joint effort starting summer 2013 between the University of Utah, University of Memphis and Norwegian Public Roads Administration. This paper includes some tasks and conceptual designs that address development of performance goals, design criteria, material testing, prototype analyses, numerical modeling and constructability of this innovative bridge support system.

Jan Vaslestad, Steven Floyd Bartlett, R. Aabøe, H. Burkart, T. Ahmed, David Arellano

Guidance on Use of Geofoam Lightweight Fill and Complementary Technologies Using GeoTechTools

Geofoam provides sustainable solutions for embankment and pavement construction, provided it is appropriately designed and detailed, specified, and installed. Prior to selecting geofoam, an engineer will evaluate the potential use of alternate lightweight fill materials and of other ground modification technologies on their project. Thus, the engineer must access and assess information on a variety of materials and ground modification techniques. Today, this information can be readily accessed on one website—www.GeoTechTools.org. GeoTechTools is a knowledge system that provides a synthesis of critically important information about geofoam, as well as other ground modification techniques, and makes the information readily accessible. The two primary components of this comprehensive toolbox are a Catalog of Technologies and a Technology Selection Assistance System. For each technology, eight distinct tools can be accessed through the Catalog of Technologies. Technology selection assistance is provided by use of an interactive selection system. This system aids the user in identifying a short-list of potential technologies for a particular project. GeoTechTools was developed to assist engineers make more informed decisions on issues to reduce risk and minimize construction surprises. The value of this system is that it collects, synthesizes, integrates, and organizes a vast amount of critically important information about geotechnical solutions on a readily accessible website. This paper discusses the system and its application on the use of geofoam for transportation projects.

Ryan R. Berg, Vernon R. Schaefer, Silas C. Nichols

N222 Roundabout upon EPS Embankment with Integrated Corrugated Steel Tunnel Structure Without Pile Foundation

In April 2015 on a location with settlement sensible subsoil surrounded by greenhouses and water channels a large roundabout has been realized using 25,000 m3 EPS geofoam blocks. The roundabout is a part of the regional road N222 which connects Flora Holland (a huge marketplace for floriculture) with the nearest highways. The region is characterized by the largest greenhouse concentration in Europe. Due to its important economic function more than 11,000 vehicles pass the new roundabout over the lightweight embankments daily. During construction, unimpeded traffic passage had to be guaranteed. Bellow the roundabout a tunnel for the passage of bicycles was designed. Adjacent power line pylons made it impossible to place pile foundations as conventionally used in Dutch areas with peat subsoil. Consequently a structure using concrete tunnels was not an option. Therefore a 3.7 m high egg-form corrugated steel tunnel structure without pile foundations was integrated through the EPS embankment. The applied tunnel system with 7-mm-thick corrugated steel plates supports lightweight foamed concrete built in around. The tunnel structure is settlement free without pile foundations. Additional advantages include its lower building costs compared with conventionally designed tunnels made of concrete. Finally, the construction time was reduced thanks to this innovative design method. The paper deals with the design aspects related to the N222 roundabout structure with the lightweight embankments in general, and with the implemented tunnel solution in particular.

Milan Duškov, Jeroen Tameling

Design and Evaluation of Seismic Stability of Free-Standing EPS Embankment for Transportation Systems

This paper summarizes a simplified method for evaluating the interlayer sliding potential of free-standing, rectangular, prismatic-shaped EPS geofoam block embankments subjected to strong ground motion associated with major earthquakes. The steps of the method are: (1) estimate the fundamental period of the embankment, (2) determine the design horizontal acceleration for the design earthquake, (3) determine the horizontal inertial force acting at each interface (4) estimate the sliding resistance and factor of safety against sliding at each interfaces and (5) evaluate the need for countermeasures, if necessary. The methods and evaluations summarized herein suggest that interlayer sliding may initiate if free-standing embankments are exposed to pulses of horizontal acceleration exceeding about 0.5–0.6 g. They further suggest that sliding is generally initiated at the lowermost interlayer and propagates upwards through the embankment to its crest. In severe cases, shear keys, adhesive bonding or other restraint mechanical mechanisms may be appropriate to locally disrupt potential sliding planes as a preventative countermeasure against interlayer sliding or excessive block movement near the outer edges of the embankment. Also, results of numerical modeling suggest that the basal edges of the EPS embankment may begin to experience overstressing due to horizontal sway of the embankment when the design horizontal acceleration values are large. For such cases, consideration should be given to using higher modulus EPS blocks at the outer edges of the basal layer to reduce the potential for overstressing.

Steven Floyd Bartlett, Zahra Amini

Expanded Polystyrene (EPS) Geofoam Columns in Expansive Soil: Preliminary Swelling Characteristics Evaluation

EPS geofoam is an excellent material for building road embankments on very soft soils, in slope stabilization, for reducing earth pressures acting on rigid structures, etc. Expansive soils give major challenges to geotechnical engineers because of high swelling and shrinkage characteristics that may severely damage the lightly loaded structures. Limited studies are available for the possible use of EPS geofoam for the reduction of vertical swelling of expansive soils. Columns techniques are preferable for deep stabilization of highly problematic soil. The use of compressible inclusion such as EPS geofoam column technique can be used to control the swelling potential of expansive soils. In this paper, an attempt has been made to study the effectiveness of EPS geofoam columns to control the vertical swelling of expansive soil with and without inclusions. For this study, EPS specimen with bulk density of 12 kg/m3 (EPS12) was chosen and column diameters were varied to study the effect of area replacement ratio (Ar) on swelling characteristics. Laboratory swell tests have been carried out on statically compacted swelling clay with and without EPS geofoam columns (EPSC) with varying diameter. Tests results show that there is a reduction in the vertical swelling of soil with the inclusion of EPSC when compared to the soil without inclusion. Also with the increase in Ar of EPSC, there is significant reduction in the swell potential of the soil.

S. Selvakumar, B. Soundara

The Effect of EPS Geofoam Thickness on the Seismic Performance of Quay Walls

Water front engineering structures have experienced earthquake induced damages from minor to catastrophic scales during the past few decades. Previous major earthquakes including the 1995 Kobe earthquake, the 1999 Kocaeli earthquake and the 2011 Tohoku earthquake showed that ports and all of its structural components are exposed to a great seismic risk. Thus, great attention should be paid by means of seismic performance in the design phase of such facilities. EPS geofoam inclusion as one of the several improvement methods can increase the seismic performance of the quay walls. It is a well-known method to reduce the magnitude of earthquake-induced dynamic forces against rigid earth retaining wall structures. The aim of this numerical study is to determine the effects of using different thicknesses of EPS geofoam cushion on the seismic performance of quay walls. Non-linear dynamic analyses were performed using the PLAXIS software. During the analyses, real earthquake records were used. Evaluation of the results reveal that inclusion of EPS geofoam as a seismic buffer decreases earthquake-induced dynamic forces against the rigid quay wall model successfully in comparison of the nominally identical structure with no compressible cushion layer. Increasing cushion thickness was found to have a positive effect on the selected performance indicators. More importantly transmitted peak accelerations within the quay wall model are reduced up to 84%. One limitation of using lightweight-compressible materials behind rigid walls may be the possibility of increased displacements and rotations which should be controlled carefully.

Ayşe Edinçliler, Yasin Sait Toksoy

Opening Traffic for a Temporarily Remediated EPS Road After the 2016 Kumamoto Earthquake: A World First

In 2016, two successive gigantic earthquakes struck the Kumamoto area of Japan, damaging many private residences and some local roads. An EPS embankment in the Mashiki area near the earthquake epicenter also collapsed. In this EPS embankment, the EPS blocks were shifted sideways because of a landslide behind the EPS fill caused by the earthquake. Nevertheless, only part of the embankment collapsed. The road surface was temporarily remediated and was maintained as it was, for the opening of traffic. This case proves that EPS gives rise to great benefits: most importantly, the collapsed EPS road was put into practical use as a temporary road.

Keiichi Taneichi, Takeharu Konami, Hideki Tsukamoto, Tatsuro Kubota, Kazuya Yasuhara

Development of Joint Metal Binder for Improving Earthquake Resistance of EPS Embankment

EPS embankments have been found to be able to ensure earthquake resistance by using joint metal binder between blocks. However, since the conventional joint metal binder is rectangular, it may act eccentric to a seismic force. There were also parts with no spikes around the metal edges, and it was pointed out that it provided a weak connection between blocks. This paper reports on the effectiveness of a new joint metal binder developed and improved on a shear testing machine.

Keiichi Taneichi, Takeharu Konami, Hideki Tsukamoto, Tatsuro Kubota, Kazuya Yasuhara

Shaking Table Test of Scaled 1/5 EPS Embankment Model

A large earthquake in the Kumamoto district in the south of Japan in April 2016 occurred twice within 28 h with a magnitude class 6.5. Due to this earthquake many houses and roads collapsed. In order to investigate the behavior of EPS embankments when a large-scale earthquake acts consecutively, an EPS embankment model with a scale of 1/5 was built and a shaking table experiment was conducted using the shaking table (3 m × 2 m) at the University of Tokyo. The EPS embankment was found to cause rocking phenomenon due to seismic motion. As a countermeasure, in addition to the effect of an improved Joint Metal Binder (JBM), the effect of applying a larger number of JMBs was also investigated.

Keiichi Taneichi, Tsuyoshi Nishi, Takeharu Konami, Tatsuro Kubota, Junichi Koseki, Hiroyuki Kyokawa, Kazuya Yasuhara
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