Lightweight Embankment Research Articles

Applicability and chemical mechanism of lightweight cement composite containing fly ash and sand for sustainable embankment

Lightweight embankment is an effective method for soft foundation treatment, while decreasing its cement usage can protect environment, save resource and reduce cost. This study aims to develop a lightweight cement composite (LC) containing fly ash and sand to provide guidance for filling the sustainable embankment. The chemical mechanism, micro-morphology, mechanical strength and workability of lightweight cement composites were evaluated through macro-micro tests, as well as life cycle assessment was performed to analyze the sustainability, and determine the optimal mixing ratio. The results showed that the moderate amount of fly ash was beneficial to enhance the mechanical strength of LC, while adding sand further improved its ductility, toughness, workability and sustainability. When the replacement rate of fly ash and sand were 10 % and 20 %, the energy absorption and fluidity of LC increased by 57 % and 7 %, and its ductility index, carbon emission and construction cost decreased by 34 %, 46 % and 35 %, respectively. Fly ash reacted with calcium hydroxide produced by cement hydration to generate more calcium silicate gels, which reduced the large pore of LC and improved its internal structure, while sand played a certain skeleton role.

Analysis of Road Embankment Improvement on Soft Soil Using Foamed Mortar Lightweight Embankment

Analysis of Road Embankment Improvement on Soft Soil Using Foamed Mortar Lightweight Embankment

Numerical Investigation of Two Methods to Reduce the Settlement of a Light-Weight Highway Embankment on Soft Soils

The development of road and highway networks sometimes involves passing through compressible soils of poor quality. Given their mechanical properties as foundation soils, these soils are characterized by low short-term shear strength, expressed by undrained cohesion, which increases during soil consolidation, and are also characterized by significant compressibility, resulting in large-scale settlements when a load is applied to them. Nowadays, there are reinforcement methods that make it possible to execute these structures while limiting the risks of instability. This study consists of the numerical analysis of a light-weight embankment of a highway section built on soft soils. Two reinforcement methods are investigated to support the embankment layers and reduce settlement. Interest is given to the behavior of the soils in place before and after the installation of the adopted reinforcement. The analysis is carried out in such a way as to show the importance of the complete consolidation of the soils in place in the long term, which makes it possible to take into account the dissipation of the pore pressures.

Application of a cement–clay–air foam mixture as a lightweight embankment material for construction on soft clay

Lightweight air foam materials can be used in pavement structures, for example, as embankments and subbase and base layers. Soft clay can be mixed with cement and air foam to generate a lightweight material. However, most previous studies have presented only laboratory test results for these materials and have not shown real-world applicability. The current study aims to demonstrate the application of a cement–clay–air foam mixture as a lightweight embankment material to reduce the settlement of soft Bangkok clay foundations induced by embankment weight. An experimental investigation to determine unconfined compressive strength (qu) was initially conducted in the laboratory to establish the ideal quantities of soft clay, air foam, and ordinary Portland cement required for embankment construction using the clay mixture. A full-scale lightweight embankment of area 14 m × 14 m and height 2.5 m was constructed on an 11 m thick soft clay layer to observe embankment settlement behavior on the soft clay foundation. The qu values of the lightweight materials obtained from the site were 1.3–1.8 times higher than those in laboratory tests. The mixtures with wet field unit weights of 0.6, 0.8, and 1.0 kN/m3 exhibited qu values of 430–620 and 770–1000 kPa, respectively, higher than the standard requirements (> 100 kPa for 7 curing days and > 200 kPa for 28 curing days). Based on monitored data, the lightweight embankment reduced settlement by as much as 80 % compared with a traditional embankment. Therefore, lightweight clay materials are recommended for use in the construction of road embankments on soft clay.

Field experiment of vibration characteristics of lightweight embankments converted from bridges using rigid polyurethane foam-filling under traffic load

The method of filling the lower space of a bridge with rigid polyurethane foam (RPU foam) to reduce the traffic load along with seismic reinforcement has rarely been applied to extend the life of bridges in Japan. This study evaluates the reinforcement effect and change in the vibration characteristics of a bridge converted into a lightweight embankment by RPU foam filling. A truck was driven on the bridge before and after the RPU foam filling. The vibration and strain of the slab were found to have reduced at the span center. When a traffic load was applied, the predominant frequency inside the RPU foam was ∼5 Hz, and long-period vibrations relative to the slab were confirmed.

Effects of geogrid reinforcement on the seismic performance of lightweight embankments

Highway embankments have experienced earthquake induced damages from minor to catastrophic scales during the past few decades despite the fact that highways are considered as major lifelines that should be in continuous operation under any circumstances. Recent advances in highway engineering suggest that geosynthetic reinforcement can be considered as a novel approach to mitigate the earthquake hazards on highway embankments successfully. The use EPS geofoam inclusions is one of the prominent improvement methods available to increase the seismic performance of lightweight embankments. It’s a well-known method to reduce the magnitude of earthquake-induced dynamic forces. The aim of this numerical study is to determine the effects of using geogrid reinforcement on the seismic performance of lightweight embankments. Non-linear dynamic analyses were performed using the PLAXIS software using real earthquake records. Evaluation of the results reveal that inclusion of geogrid reinforcement layer beneath the lightweight embankment model successfully decreases earthquake-induced dynamic forces and increases the seismic performance of the embankment model in comparison of the nominally identical structure with no geogrid reinforcement. Numerical results obtained from this novel technique suggest that the implementation of a geogrid layer beneath such lightweight embankments can successfully and effectively increase the seismic performance of such structures.

A Practical Design Method to Determine the Replacement Time of Light Embankment

If the settlement of bridgehead transition section of expressway is too large, it often causes frequent vehicle jumping at bridgehead and endangers passenger safety. The engineering practice has proved that the lightweight embankment replacement technology can reduce the postconstruction settlement effectively, thus reducing the occurrence of bridgehead jump. The key of filling technology of lightweight embankment is the design of filling thickness and the selection of filling time. This paper deduced how to determine the replacement time of lightweight embankment in practical engineering. In order to apply to engineering practice more conveniently, this paper made the following assumptions: (1) For normally consolidated soil, the elastoplastic deformation at any point of soil under external load can be equivalent to the sum of instantaneous elastic deformation and creep based on equivalent time. The corresponding pore ratio change also has corresponding equivalent relation. (2) The increase of equivalent time is ignored during unloading, filling, and paving process. Based on the above two assumptions, according to 1D EVP model and the conception of equivalent time, the unloading time and filling time of light embankment for layered soil foundation are deduced. It is applied to the design and calculation of the supporting project.

Experimental study on the dynamic properties of rigid polyurethane foam in stress-controlled cyclic uniaxial tests

Frequent major earthquakes in Japan necessitate earthquake-resistant infrastructure. The dynamic deformation characteristics of rigid polyurethane foam, used as a lightweight embankment material, is examined in this study. The effect of the initial static stress on the shear modulus of single-layer samples was small, while the shear modulus of two-layer samples increased with increasing initial static stress. The damping ratio of single-layer samples converged to 4–5%, but decreased with increasing initial static stress up to 30 kPa in two-layer samples before increasing above 40 kPa. Results from cyclic uniaxial and triaxial tests were compared. The dynamic properties depended on restriction conditions and the deformation direction.

Experimental study on earth pressure reduction of waste tyre bales used as a backfill for rigid retaining structures

Abstract Waste tyre-derived products, including whole tyres, tyre bales, shreds, chips and crumb rubber, have been widely used in geotechnical applications. In particular, tyre bales have considerable potential for use in the construction of a lightweight embankment or road foundation over soft ground, slope stabilisation or landslide repairs and the backfilling for retaining structures. Proper design of tyre bale structures requires a reliable strength analysis to ensure an adequate factor of safety. The analysis should utilise the properties of the tyre bales and the baled structures, which must be properly determined. A laboratory test programme was developed to determine the key strength parameters of a backfill made of tyre bales supplemented with a lightweight aggregate. Full-scale direct shear tests were conducted to define the interface shear strength between the tyre bales and the filling material. Earth pressure reduction analysis based on the experimental results was performed as well to assess the effectiveness of waste tyre bales used as a backfill for rigid retaining structures.

Stability and Settlement Analysis of a Lightweight Embankment Filled with Waste Tyre Bales over Soft Ground

The waste tyre-derived products, including whole tyres, tyre bales, shreds, chips, and crumb rubber, have begun to be used in various geotechnical applications. In particular, the use of tyre bales in the construction of a lightweight embankment on the soft ground has the potential to satisfy the demand for low-cost materials exhibiting such beneficial properties. This paper presents the comparison between the common medium sand-filled embankment and two tyre-baled structures with various granular interlayers: medium sand and rubber aggregate. To assess the efficiency of tyre bale application in soft ground conditions, two subsoils were considered in the study: sandy clay and silty clay. The stability and settlement analysis of embankments, as well as subsoil bearing capacity checking, were performed for all structural cases. Bishop’s limit equilibrium slicing method and the finite element method were used in the embankment and subsoil analysis. The comprehensive testing of tyre bales and filling materials was also carried out to obtain the set of parameters used in both analyses. The comparison allowed qualitatively assessing the effectiveness of using waste tyre bales as a filling of road embankment when founded on soft ground. The analysis revealed that the application of tyre bales generally enhanced the embankment stability, effectively reduced the embankment settlement, and reduced the normal stress in the subsoil. In the tyre-baled embankments, the slip surface is located mostly within the embankment slope, showing good rotational stability, independent of subsoil conditions.

DYNAMIC PROPERTIES OF RIGID POLYURETHANE FOAM IN CYCLIC TRIAXIAL TESTS

The aim of this study is to clarify the dynamic properties of rigid polyurethane foam. A method for renovating a deteriorated bridge as a lightweight embankment was proposed. The space underneath a bridge is filled with polyurethane to support the upper structure. In this case, the upper structure of the bridge is considerably heavier than the polyurethane. Therefore, it is important to examine the seismic behavior of this new lightweight embankment. However, the dynamic deformation characteristics of polyurethane have not been clarified previously. In this study, stress-controlled cyclic triaxial tests based on JGS0542-2009 are used to evaluate the effect of the confining stress and the presence of a rigid layer on the dynamic properties of rigid polyurethane foam. As a result, the shear modulus of rigid polyurethane foam increases with increasing confining stress regardless of the absence of the rigid layer. The shear modulus of polyurethane with the rigid layer is lower than that of polyurethane without the rigid layer. The value of shear modulus of rigid polyurethane foam was measured in the range of approximately 1.6~3.2MPa. Moreover, the stiffness degradation and of rigid polyurethane foam are in good agreement with the Hardin-Drnevich model.

Karakteristik Mekanis Material Geokomposit Ringan Tanah – EPS Stabilisasi Fly Ash

This laboratory experiment intended to develop lightweight embankment material in using fly ash as a stabilized agent on soft soil and the addition of expanded polystyrenes (EPS). The fly ash derived from combustion of palm shells and tea in drinks manufacture process. In order to analyze the performance of this material, compressive strength test were applied to several composition and treatment on each sample. The samples were prepared with composition of binding agent between 3%, 5%, 10% and 15% based on samples weight, meanwhile the addition of EPS with composition 10% and 20% based on samples volume. The results presented that the highest compressive strength were founded at 5% of POFA, further it is noted that the inclusion of EPS as a soil subtitution decrease the compressive strength. While, the curing periods have a significance effect on the engineering properties of lightweight materials.

Stability analysis of an expansive soil-embankment slope with a soft interlayer

The soft interlayer in the foundation is one of the most important factors that induce landslide in the expansive soil-embankment slope. The existence of large soft layers significantly reduces the overall stability of the slope, and they have the tendency to further develop into a sliding surface. To investigate the influence of the soft interlayer on expansive soil slopes, taking the high-fill embankment slope with a soft interlayer in the Baoshan area of Yunnan Province as an example, the causes and strength effects of the soft interlayer are analyzed via landslide investigation, laboratory test, and numerical simulation, and the stability and instability mode of the slope are studied. Results indicate the following: ① The soft interlayer is located at the bottom of the weathering layer within the depth of the atmosphere. Its strength is less than that of the expansive soil on both sides. ② The overall stability of the slope and the shape of the sliding surface are controlled by weak interlayers, and its strength greatly impacts the damage scope of the slope. When the strength is high, it appears as a collapse of the fill area, and when the strength is extremely low, it appears as the overall sliding of the slope. Using the residual strength as the calculation parameter of the weak layer reflects well the actual stability and failure mode of the slope. ③ Results of soil layer parameter sensitivity analysis indicate that the internal friction angle of the soft interlayers has the most significant effect on slope stability. Using the lightweight embankment fill can effectively improve the stability factor of embankments.

Compressive strength of lightweight geocomposit soil-eps stabilized with palm oil-tea fly ash

This laboratory experiment intended to develop lightweight embankment material by using fly ash as a stabilizer agent on soft soil and the substitution of soil with expanded polystyrenes (EPS). The palm oil-tea fly ash (POTFA) derived from combustion of palm shells and tea in manufacture process. In order to analyse the performance of this geocomposite material, compressive strength test were applied to several composition and treatment on each sample. The samples were prepared with composition of binding agent for 5%,10%,15% and 20% based on dry weight of the soil, meanwhile the EPS composition are 10% and 20% based on sample’s volume. The results showed that the substitution of EPS will reduce the unit weight of geocomposite material until 30% compared to untreated soil. The compressive strength will decrease slightly with the augmentation of bonding agent content on the samples as well as the addition of EPS, however that results are still higher than normal soil.

LIFE CYCLE IMPACT ASSESSMENT OF NEW GROUND MATERIAL AND EMBANKMENT CONSTRUCTION METHODS CONSIDERING RECYCLING

In Japan, the conventional cut-and-fill method is often used in banking construction methods. However, this construction method is pointed out that it causes land subsidence and/or landslide in soft ground. For solving these problems, various new construction methods using the ground materials such as EPS (styrofoam), recycled foamed waste glass and expanded polystyrene beads have been developed as a new lightweight and workable composite geomaterials. These new construction methods are believed to be effective for construction on soft ground and landslide-prone areas. In existing researches of this field, they aimed to identify areas for improvement and the problems associated with the use of these new ground materials. However, there are few types of research that focused on negative impacts on land use, by exhausting air pollution and GHGs (Green House Gases) with recycling from the perspective of the environmental economics field. Thus, in this research, we compared conventional cut-and-fill method and some new ground materials such as the expanded polystyrol construction method using the new EPS geomaterial, the lightweight embankment construction method with EPS beads and the foamed waste glass construction method using embankment material with recycled waste by analyzing the negative impacts to land use considered ecosystem services and life cycle cost (LCC) including external cost by emissions of GHGs and air pollutants such as SOx and NOx using life cycle impact assessment analysis.

О проблеме проектирования и расчета конструкции облегченных насыпей из пенополистирольных блоков на слабых грунтах

О проблеме проектирования и расчета конструкции облегченных насыпей из пенополистирольных блоков на слабых грунтах

Material and Behavior Characteristics of Lightweight Embankment for Road Constructed on Soft Ground

Material and Behavior Characteristics of Lightweight Embankment for Road Constructed on Soft Ground

Geotechnical Engineering Properties of Fly Ash and Bottom Ash: Use as Civil Engineering Construction Material

Norochcholai coal power plant is the largest coal power plant in Sri Lanka and during the combustion of coalit annually generates about 250,000 metric tons of coal ash which consists of fly ash (FA) and bottom ash (BA). Almost all the generated ash is disposed into ash dumps except a small quantity of FA (30%) that is effectively utilized. Therefore, use of coal ash for construction purposes will offer a sustainable solution for reducing its by-products and overcoming the scarcity of raw materials required for construction work. The main aim of this research was therefore to determine the geotechnical engineering properties of FA and BA to find out the feasibility of using them as light weight embankment or backfill material. A series of laboratory experiments were conducted on FA, BA and FA-BA co-mixed samples to determine their particle size distribution, specific gravity, index properties, compaction characteristics, shear strength parameters and California bearing ratio (CBR). The experimental results reveal that the particle size of coal ash (FA and BA) is predominantly silt sized while containing some sand-sized fractions as well. This coal ash has a low maximum dry density (MDD) and a high optimum moisture content (OMC) compared to typical granular soils used in embankments. In addition, this ash has a higher friction angle and higher cohesion than most types of construction fills. Thus, both FA and BA can be used as light weight embankment or back fill material in civil engineering construction work.

Key Technology Research into Foam Concrete Lightweight Embankment with Cast-in-Situ Baffle instead of Conical Slope at Bridge-head

According to the features of foam concrete of low density, small load on foundation after filling to greatly reduce ground treatment intensity and no need for dynamic compaction or rolling after pouring so that pavement structure layer can be directly laid, in this paper, a construction method was, with inside step-slope on embankment, cast-in-situ concrete baffle structure on the outside of embankment and foam concrete to fill bridgehead subgrade, explored to solve the problem of earth pressure and conical slope setting at abutment as well as optimize abutment to be the structure without conical slope, so as to reduce the span which may be enlarged due to conical slope and greatly cut project cost. At the same time, using this method, settlement and uneven settlement decreased and post-construction settlement of abutment filling was eliminated so as to avoid bumping at bridge-head and reduce maintenance cost.

Key Technology Research into Foam Concrete Lightweight Embankment with Prefabricated Baffle Instead of Conical Slope at Bridge-Head

In order to solve the problems of bridgehead diseases and reduced space under bridge due to conical slope at bridge-head, in this paper, a construction method was explored to utilize inside step-slope on embankment, prefabricated baffle structure on the outside of embankment and foam concrete, with self-supporting after solidification, low elastic resistance, adjustable strength and durability, to prevent vehicle bumping and, without conical slope, to enlarge the space under bridge. It has excellent technical and economic benefits.