Expanded Polystyrene Block Research Articles

Evaluation of the Performance of Expanded Polystyrene Block on the Reduction of the Deck Cracking in Wide Integral Abutment Bridge

Longitudinal joints are thought to provide relief from expansion and contraction of the bridge deck owing to temperature change, shrinkage, and live loads, especially for a wide bridge. Historically, however, these joints have been known to leak, allowing chloride-laden water to reach the bottom of the deck overhang and even the exterior girders. Research conducted by Phares et al. indicated that the development of cracking in bridge decks seems less dependent on the total width of the deck and more so on internal restraint of the abutment to temperature changes and, in particular, gradients. Based on the finite element method (FEM) results, an effective solution to reduce cracking in the deck might be to place an isolation pad between the soil and the back side of the abutment. The primary objective of this paper is to investigate the effectiveness of an isolation foam block at the back of an integral abutment in reducing the stress-induced strain and the deck end longitudinal and diagonal cracking near the end of the deck with an integral abutment. To achieve this objective, a highway bridge (Viking Road Bridge) in Iowa, US, designed with a width of 228 ft, was selected for the study. The bridge deck has no longitudinal joints but, based on the previous research results, it was equipped with thermal isolation pads behind the abutment. The newly constructed bridge was monitored for over two years, and this was followed by multiple bridge inspections. An analytical study was conducted to investigate the efficiency of the isolation foam on the bridge deck end structural behavior. The results indicated that the thermal isolation foam is effective in reducing the temperature gradient through the abutment thickness, especially on extremely cold days. By reducing the temperature difference between the abutment and the deck, a thermal isolation block is effective at reducing the deck end strain and resisting deck end cracking. The FEM results indicated that the maximum deck stress-induced strain was 46% greater without the effects of the thermal isolation block and greater than the concrete cracking strain. This indicated that, without the thermal isolation pad, the Viking Road Bridge could crack at the end of its deck.

Numerical Modelling of Soft Soil Improvement Using Expanded Polystyrene Geofoam for Road Embankment

Soft soil brings abundant engineering issues due to low bearing capacity and shear strength. A comprehensive study of soft ground needs to be reviewed and identified before construction can start. Various techniques can be used to improve the soil. However, this study focuses on using material namely expanded polystyrene. The geotextile is embedded with expanded polystyrene to strengthen the soil condition. This study adopted the soil parameters from East Coast Expressway. There are two models in this study, which are earth embankment and EPS embankment. The settlement of the earth embankment is compared with the EPS embankment after construction. The Mohr-Coulomb parameters are used to model the soft soil and embankments, while the linear elastic parameters were adopted to model the EPS and geotextile. This study produced two embankment models, the conventional embankment models with and without surcharge. The second model is an EPS embankment with various densities (22 kg/m3, 29 kg/m3, and 39 kg/m3). The settlement is recorded for ten years after the embankment construction was completed. The difference settlement value for the conventionalmodel is 28mm. The settlement value for EPS 22 is 3.18mm, EPS 29 is 2.06mm, and EPS 39 is 1.51mm. For the geotextile embedded in EPS, the settlement for EPS 22 is 3.17mm, EPS 29 is 2.04mm, and EPS 39 is 1.49mmrespectively. Since EPS uses three different densities, from the prediction of PLAXIS 2D, the higher density gives the lower value of the settlement. However, when the geotextile is embedded with EPS, there is no significant difference in settlement behaviour. In conclusion, the model with a surcharge gives a lower settlement than themodel without a surcharge. But the expanded polystyrene block is the best model to reduce the settlement compared with the conventional model with a surcharge. Different densities of EPS resulted in different settlement value, and EPS 39 gives the lowest settlement value. In terms of the geotextile embedded with EPS, it does not give a significant change in settlement.

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.

Thermal insulation materials based on agricultural residual wheat straw and corn husk biomass, for application in sustainable buildings

The high energy consumption in buildings is a major contributor to climate change and atmospheric pollution in south cities of Chile. In this context, insulation materials are a key factor to reduce the energy demand during the operational stage of a building. These materials are however commonly fabricated from petrochemicals with high energy consumption, causing significant detrimental effects on the environment during the production and discarding stage. Due these reasons, insulation materials based on natural fibers waste appear as an excellent alternative, due to abundant availability in south regions of Chile, potential low cost, low energy consumption during the production stage and high bio-degradation rate at the end of life. In this research, block type insulation based on wheat straw and corn husk residual fibers were developed. Taguchi method was applied to investigate the effect on thermal conductivity and density of four control factors in three levels, namely fiber length, boiling time; NaOH concentration and blending time; in a L-9 orthogonal array. Furthermore, flexural and compressive stress were determined and compared with expanded polystyrene block insulation. The results show thermal conductivity values were between 0.046 and 0.047 W/mK. In addition, flexural stress results were good compared to those of the standard expanded polystyrene type IX. Finally, optimum conditions of the process were determined to obtain a final block, which was morphologically analyzed using scanning electron microscopy (SEM), while the thermal behavior was studied by thermogravimetric analysis (TGA).

Morphological Decision Making for Amphibious House Platform as a Sustainable Flood Protection Strategy

The concept of amphibious houses has a broad range of application as a sustainable and multi-reason solution for flood protection. Based on the current materials and methods for implementation of the amphibious house, an optimal morphology is required to be achieved. Different morphologies for the buoyant component should be evaluated under four classifications towards sustainable development. This study evaluated the best design and material for floating part in amphibious houses based on technological, environmental, economic, and social classifications. This study applied the multi attribute decision making model using relevant criteria for applying amphibious house as a flood protection strategy in floodplain areas in South-East Asia. The bucket system (pontoons) which is made by lightweight concrete and using expanded polystyrene block inside is identified as an applicable morphology for buoyant part in amphibious houses.

Interface Shear Strength Characteristics of Interlocked EPS-Block Geofoam

AbstractLightweight fills constructed by the use of expanded polystyrene block (EPS-block) geofoam (geofoam block) is known to be susceptible to horizontal loading since the vertical pressure which enhances the shear resistance along the interface of individual blocks is low. Therefore, research has focused on the methods to increase the interface shear resistance of geofoam blocks. This study investigated the use of interlocking mechanisms by conducting direct shear tests on four different interlock configurations. An interlock configuration utilized a number of ledges and notches to interrupt the continuous horizontal shearing plane in-between geofoam blocks. Two different densities of geofoam blocks (EPS19 with a minimum density of 18.4 kg/m3 and EPS29 with a minimum density of 28.8 kg/m3) were used in order to investigate the effect of material hardness on stress-strain behavior and interface friction properties. The results of this study showed that the interlocking mechanism improved the interface...

Static Load Tests in an Instrumented Rock Socket Barrette Pile

The foundation for the new Petrobras headquarters building in Salvador, Bahia, northwest of Brazil, had barrette pile rock socketed units chosen as the best engineering solution, due to shallow top rock, given schedule and cost. Even though the soil strata was stiff to very stiff silt, the required design load was not able to be based on soil side resistance only, resulting in a rock socket design. A 300 kPa ultimate shear stress was assumed by the designers and static load tests were performed to verify this parameter. This paper evaluates the results obtained from the test without discussing the designer assumption. Rock socket shear stress verification was made possible by placing an expanded polystyrene block below the pile steel cage, eliminating any possible bottom resistance. Beyond the usual top instrumentation, electric retrievable extensometers were installed along the shaft to afford depth load transfer evaluation. This paper presents the results of the load tests as well as an application of analytical and semi-empirical methods available in the literature to prove their usefulness and effectiveness, revealing and confirming many aspects of field behavior.

Lightweight backfill materials in integral bridge construction

Analysis of integral bridge structures shows that lateral earth pressures on the end abutments have a dominant influence on the sizing of bridge components. Thermal cyclic movements induced by deck expansion cause densification of backfill material, leading to the build-up of high pressures behind the abutments. Measures to reduce these pressures by the use of alternative backfill materials can be highly beneficial to the structure as a whole, with extra expenditure on the backfill material being offset, and in some cases exceeded, by savings in material quantities in the rest of the structure and build time. This paper examines three contrasting backfill options that were considered during the design of Cottington Road overbridge in Kent: 6N granular backfill; lightweight expanded clay; and expanded polystyrene blocks. Although more expensive as a material than the other options investigated, the expanded polystyrene block option was selected as the most economical solution for this particular structure owing to large material savings in the foundations, abutment walls and wing walls as a direct result of reduced lateral pressures. Although it did not form part of the decision-making process, this paper also shows a significant saving in embodied and transport-related carbon dioxide emissions through preferring expanded polystyrene blocks to expanded clay.

Numerical Simulations of Rockfall Protection Retaining Wall Joined to Steel-Pile Foundation

In Japan, many rockfall protection walls have been constructed along the nationalhighways in mountainous areas. Up till now, usually these were gravity-type walls. However, ifthere is not much space between the wall and the edge of the cliff, it may not be easy to constructa normal type of wall. To rationally install the wall in these areas, a retaining wall connectedto a steel pile foundation attached to a two-layer absorbing system was recently developed.Here, in order to establish a rational design for this type of retaining wall, an impact responseanalysis was performed by means of three-dimensional elasto-plastic FE analysis. The two-layerabsorbing system used here is composed of a 15 cm thick reinforced concrete slab together with a50 cm thick expanded polystyrene (EPS) block. The retaining wall is connected to the steel pilesby inserting H-section steel members embedded in the wall. The applicability of the proposedFE analysis method was verified by comparing with the prototype impact test results.

Framework for Design Guideline for Expanded Polystyrene Block Geofoam in Slope Stabilization and Repair

This paper presents the framework for the interim design guideline for the use of expanded polystyrene (EPS) block geofoam for slope stabilization and repair, based on the findings of the NCHRP Project 24-11(02) Phase I study. The overall objective of this research is to develop a design guideline as well as an appropriate material and construction standard for the use of EPS block geofoam for the function of lightweight fill in slope stability applications. The recommended design methodology included in the framework is based on an assessment of the existing technology and literature. The Phase II work will refine the interim design guideline framework and address some uncertainties in the current state of the practice of analyzing various failure mechanisms included in the design procedure. The completed research will consist of the following five primary research products: (a) a summary of the relevant engineering properties, (b) a comprehensive design guideline, (c) a material and construction standard, (d) economic data, and (e) a detailed numerical example. No formal design guidelines on the use of any type of lightweight fill for slope stabilization by reducing the driving forces are available. Therefore, the proposed interim design guideline for EPS block geofoam can serve as a blueprint for the use of other types of lightweight fills in slope stability applications. The NCHRP Project 24-11(01) and the Project 24-11(02) Phase I research confirmed that EPS block geofoam is a unique lightweight fill material and can provide a safe and economical solution for slope stabilization and repair.

A new method of shipping and handling tachnid parasites ofParopsini [Col.: Chrysomelidae

A method of holding tachinid puparia in individual gelatin capsules securely held in holes in an expanded polystyrene block, and the advantages in handling, shipping, and collection of emerging insects are described.