Sustainable Construction Resources in Geotechnical Engineering

The Yellow River silt (YRS) is commonly used as construction material to address lack of sand resource. However, the YRS has the shortcoming of poor mechanical characteristic. Hence, in current study, enzyme-induced calcite precipitation (EICP) and microbial-induced calcite precipitation (MICP) techniques were adopted as the reinforce measures for the purpose of promoting the engineering properties of YRS. Among various factors that may influence the solidification effect, concentration of cement solution C and the number of grouting times N were selected for emphatical inspecting. Technical measures including unconfined compressive strength (UCS) test, the CaCO3 content test, and scanning electron microscope (SEM) were utilized to assess the solidification effect with different biotreatment technology. The results show that the YRS samples solidified with EICP technology can reach higher UCS and CaCO3 content. Compared to MICP technology, EICP technology is more capable of enhancing the geotechnical properties of YRS. The findings of this study can make contribution to the resource utilization of YRS.

The area of seaweed beds along Japanese coasts has decreased by approximately 40% in the last 40 years due to climate change and human activity. In addition, there are similar concerns regarding coastlines worldwide. Thus, it is critical to recover seaweed communities quickly to maintain marine plants and environments. On the other hand, the treatment of disaster waste like decomposed granite and Shirasu in Kyushu region is getting a big problem when a disaster due to heavy rain has occurred. Large amounts of waste material such as scrap ceramics and gypsum are discharged from the ceramics industry in the Saga and Nagasaki Prefectures of Kyushu, Japan. The effective use of disaster and industrial wastes (problematic soils, scrap ceramics and gypsum) represents an important problem that must be solved in the Kyushu region of Japan. The objective of this study is to develop environmentally oriented base materials for seaweed beds with a low environmental load using several recycled materials from disaster and industrial wastes. The developed base materials were placed into the actual sea area in September 2021, and monitoring began. A discussion of the results of long-term monitoring over 1 year is presented.

Microbial-induced calcium carbonate precipitation (MICP) is a promising approach to improve the geotechnical engineering properties of granular soils. MICP has advantages of environment friendliness, low disturbance, low cost, etc. Calcareous sand is a special type of granular soil, and its particles are highly irregular and angular. In this paper. a series of experimental tests were undertaken to investigate the influence of soil particle morphology on the efficiency of the MICP process in calcareous sand. Effects of the concentration of bacteria solution and grouting method were quantified and compared in terms of calcium carbonate (CaCO3) content and unconfined compressive strength (UCS). The results show that fractal dimension of the calcareous sand particle ranges from 1.08 to 1.21. Period of 10–35 h after activation is the logarithmic growth stage of the bacteria. Single-phase grouting is better than two-phase grouting method. The UCS of the MICP-treated calcareous sand specimens is about 300–700 kPa and it has an exponential distribution with the CaCO3 content.

As a temporary construction method that contributes to SDGs, it is a construction method that makes it possible to pull-out steel earth-retaining piles such as steel sheet piles while suppressing the subsidence of the surrounding ground. There are about 50 achievements in. It can be safely pulled out in close construction of railways, buildings in urban areas, etc., and it is possible to recycle steel materials, reduce costs, make effective use of underground space, and prevent the spread of soil contamination.

In order to transport high-moisture sludge dredged in the sea area to a waste disposal site, it is essential to reduce the moisture content ratio of dredged sludge. Therefore, we devised a volume reduction system for high-moisture sludge and applied it at Dokai Bay located in Kitakyushu City. The volume reduction system consisted of a two-step process, a dewatering process and a cement reforming process. The moisture content ratio (wn) of the dredged sludge was more than 200%, and the moisture content ratio (wn) of the dehydrated cake discharged from the screw decanter centrifuge was about 100%. As a result of adding an appropriate amount of cement-based solidifying agent according to the moisture content ratio of the dehydrated cake, it was possible to transport the treated soil in a dump on the day after dehydration. The reforming dredged sludge cured in the temporary storage yard satisfied the required quality (cone index qc ≧ 400 kN/m2). The actual dredging amount was 17,157 m3 and the reformed soil volume after the addition of the cement-based solidifying agent was 6072 m3. By applying a volume reduction system, the volume reduction rate of dredged sludge was achieved at 35.4%.

Since soil material produced at construction sites is soft, it is mixed with a stabilizer (e.g., cement, lime) as a way to use it more effectively if it cannot be used for earthworks as such. By mixing soft soil with a stabilizer that enhances strength, this method improves the soft soil. However, as solidification continues to progress after construction, the material may become stronger than is necessary, complicating re-excavation. If constructed on soft ground, it may also cause cracking of an earth structure because it cannot follow ground subsidence. Therefore, the authors focused on crushed solidified soil as a material with low strength development even when mixed with a solidifier and conducted studies on its use as a civil engineering material. Crushed solidified soil is prepared by mixing the target soil with a solidifier and crushing it after a certain period of time to make it compactable. If an embankment is constructed using crushed solidified soil, it is considered appropriate to use a quality management method based on the degree of compaction as with construction using ordinary soil. Therefore, we conducted a compaction test on crushed solidified soils prepared using several different soil materials as well as different conditions. As a result, it was found that the compaction curve of crushed solidified soil was influenced by the original soil, solidifier, time mixing with a solidifier to crushing and time from crushing to the compaction test.

The reinforced soil is a very cost-effective technique to improve the stability and control the deformation by inserting tensile elements in the soil. When load acts on the composite soil reinforcement system, soil generates tensile loads in the reinforcements. These loads restrict the soil movements and impart the additional shear strength. Geogrid is one of the geosynthetic materials used to reinforce soils. Handling and disposal problems of flyash can be reduced by using flyash as a construction material in geotechnical engineering applications. ADTA (automated dynamic testing apparatus) is a computer-controlled device runs on a Movicon software and is used in the present investigation to apply the cyclic load on the footing. Both unreinforced and reinforced flyash beds are prepared by manual compaction at its MDD and OMC. The flyash beds having reinforcement at a spacing of 0.3 times width of footing perform better than the reinforcement at a spacing of 0.4 times width of footing for all loading conditions for footing. Footing embedded at a depth of two times of the width of footing performs better by taking more number of loading cycles and undergoing less settlement when compared to footing embedded at a depth of one times the width of square footing.

Disposal of scrap tires is of great concern across the globe. As scrap tires are durable in nature, their derivatives are recommended for various civil engineering applications. Filling materials in the embankments, drainage materials, etc., are few applications suggested by various recent studies. The present study investigates the effect of tire derivative particle size on the dynamic properties and liquefaction behavior of sand-tire derivative mixes. A series of strain-controlled cyclic triaxial tests were carried out considering strain amplitude, confining pressure, percentage of tire derivative and type of tire derivative as variables. A sample of 100 mm × 200 mm was considered in the study. All the samples were prepared at a density index of 60% by using dry pluviation method. The dynamic properties and liquefaction behavior, in terms of the excess pore pressure ratio, for all the mixes are detailed in the paper. A proper comparison of the behavior of different sized tire derivatives and their mixes are presented.

This research investigated the suitability of using recycled aluminum salt slag (RASS) and crushed concrete aggregate (RCA) as virgin quarry aggregates substitution in geotechnical applications. The RASS and RCA were characterized by conducting an extensive series of geotechnical and environmental engineering tests and microstructural analysis. 3% GP cement was used to stabilize RASS and RCA blends, and the strength performance of the stabilized mixtures was subsequently measured. The results showed that RASS and RCA conform to the requirements specified by the local road authority for usage in road work applications. A comparison of leachate test results with the specifications stipulated by the EPA Victoria and the US EPA implies that RASS and RCA have negligible effects on the environment throughout their service life in a project. In addition, the UCS of cement-stabilized RASS and RCA blends also met the minimum 7 days strength requirement recommended by the Texas Department of Transportation for Class L and Class M materials in road work applications.

Retaining walls are designed considering lateral pressure acting on the walls due to retained backfill, traffic and seismic loads, etc., and the reduction in the lateral pressure exerted on the wall would lead to a reduction in construction costs. The provision of a compressible inclusion between the wall and backfill changes the stress state in the retained wall, resulting in a significant reduction in lateral pressure on the wall. Expanded polystyrene (EPS) geofoam is a suitable inclusion material due to its lightweight, predictable stress–strain response, availability, and ease of installation. Though several studies were reported on the use of EPS geofoam to reduce earth pressures on retaining walls, most of the studies were based on small-scale model tests, and understanding the effect of EPS geofoam through full-scale instrumented studies is very essential. In the present study, fully instrumented field tests are conducted to check the suitability of EPS as an inclusion material to reduce the earth pressures on a rigid reinforced concrete cantilever retaining wall. A wall of 6 m in height and 8 m in length is constructed, divided into two sections of 4 m each. Each section is instrumented with earth pressure cells (EPC) for pressure measurement. A 250 mm thick EPS15 inclusion is used in one section, and in another section, no inclusion is placed. The response of EPC in both sections is continuously monitored during the backfilling process. The results clearly show significant differences in the response of EPC on sections with and without geofoam.

Rice Resin® is a biomass-sourced plastic material upcycled from discarded inedible rice, such as old rice and broken rice generated by rice factories. Rice resins are plant-based materials, essentially making them eco-friendly. They can reduce CO2 emissions by almost 30% compared to conventional petroleum-based plastic products. Therefore, the realization of the SDGs can be easily ensured with the utilization of this material. Rice resins are granular materials and therefore can be used as the drainage enhancing materials for soil improvement. The objective of this research is to clarify the physical and mechanical properties of rice resin, which has potential to use as liquefaction prevention (drainage effect) material. For this purpose, particle size distribution test, density test, minimum and maximum density test of rice resins were conducted. Furthermore, a medium-scale triaxial compression and permeability testing apparatus was used to conduct the consolidated-drained (CD) triaxial compression test and the constant head permeability test. The findings of this study are as follows: (1) The shear strength of rice resin is smaller than that of the gravel and larger than that of tire chips, which are currently used as a substitute material for gravel, (2) the volumetric strain of rice resin shows the same shrinkage and expansion as that of gravel, (3) the angle of rice resin is slightly smaller than that of gravel, (4) the permeability of rice resin is similar to that of gravel, making it an effective-drainage material in liquefaction prevention of ground.

In order to study accumulated deformation characteristic of Yellow River silt under long-term cyclic loading, a series of dynamic triaxial test was conducted. The effects of confining pressure, relative density, loading frequency and cyclic stress ratio on accumulated deformation behavior were studied. The results show that the accumulated strain increases as the confining pressure and cyclic stress ratio increase. The increment of relative density and loading frequency will restrain the increase of accumulated strain. Based on test results, accumulative strain prediction model that can reflect the effects of confining pressure, relative density, loading frequency and cyclic stress ratio was proposed. By comparing the measured curve and the predicted curve of accumulated strain, it can be concluded that the prediction model developed in this study is applicable for the Yellow River silt. These findings offers some insight into the deformation estimation and prediction of subgrade with Yellow River silt.

The pre-bored grouted planted (PGP) pile is a composite pile foundation consisting of a PHC pile and the cemented soil around the pile. In this research, the industrial solid waste such as fly-ash, slag, gypsum were adopted to manufacture stabilized soil. A series of unconfined compressive strength (UCS) tests and pile-stabilized soil interface shear tests were conducted to investigate the frictional capacity of pile-stabilized soil interface. The test results showed that the strength of stabilized soil with mass ratio of 5% cement, 15% slag and 2.5% gypsum was 1210 kPa after being cured for 3 days, which was 7.74 times the strength of cemented soil with 20% cement content. There was no direct relationship between the peak skin friction of pile-stabilized soil interface and the strength of stabilized soil. The peak skin friction of pile-stabilized soil interface was 31.2 kPa for the stabilized soil with 10% cement, 10% slag and 2.5% gypsum, which was 1.24 times the peak skin friction of pile-cemented soil interface.

The soft clay layers are widely distributed in Southeast China, and the soft clay is of very poor engineering property. The properties of soft clay needs to be improved in advance when the engineering construction projects are carried out. In this paper, mineral powder and fly ash were mixed with cement as the curing agent, and gypsum was used as the activator to stabilize the soft clay. A series of unconfined compressive strength tests and direct shear tests were conducted to investigate the strength of stabilized soil with different ratio. The test results showed that the increase of gypsum content could largely improve the strength of the stabilized soil, while the increase of mineral powder and fly ash did not have a large effect on the strength of stabilized soil. The increase of strength of stabilized soil with curing time was similar to that of cemented soil, and the deformation modulus was about 30.2–119.7 times of unconfined compressive strength. The strength of stabilized soil reached the peak value in this research when the ratio of cement clinker to mineral powder was 6:4, fly ash content was 7.5%, and gypsum content was 20%. The maximum strength of stabilized soil was 994 kPa after being cured for 28 days, which was 2.7 times the strength of cemented soil. There was an obvious linear relationship between unconfined compressive strength and cohesion of stabilized soil, which could be expressed as c = 0.21qu.

Nowadays, globally rapid increase in the production and demand of furfural oil due to its many viable properties and best alternative to petroproducts. Furfural-extracted corncob ash (FECA) is a residue generated from the furfural production industry. However, during the furfural extraction process, the bulk of corncob ash was developed, and dumping the residue poses an environmental threat. This paper presents the efficacy of the FCEA as a geomaterial in construction. A series of tests was conducted on FCEA blended clays to determine free swell index, compaction, and California bearing ratio (CBR) tests. Maximum dry densities and CBR values were significantly improved with an increase in FCEA content. The test results indicate that the FECA is a desirable material for construction activities. The paper also explores the potential selection of better geomaterial for construction. Because in most cases, the choice of additives predominantly relies on the engineering properties of the material. Such an exposition may cause an increased cost of the project due to the cost of the selected geomaterial.

Phosphogypsum (PG) is an industrial waste of the phosphoric acid industry and is mainly composed of calcium sulphate. PG has sufficient mechanical strength to be used for secondary road embankments and base material. However, due to the presence of toxic substances, the use of PG is limited in road construction and ground improvement projects. This paper presents geotechnical, microstructural, and leaching characteristics of raw PG obtained from the Odisha State of India. The microstructure and crystalline phases of raw PG were investigated by scanning microscope (SEM) and X-ray diffraction (XRD) analysis. The compaction characteristics were examined for both air-dried and oven-dried PG. The mechanical properties were investigated by performing unconfined compression strength (UCS) and California bearing ratio (CBR) tests. The water leach and toxicity characteristics leaching procedure (TCLP) tests were also performed to assess the environmental risks. The findings revealed that air-dried PG has a significantly lower maximum dry density than oven-dried PG. The air-dried UCS specimens were broken and damaged during demoulding, indicating poor strength, whereas oven-dried PG showed sufficient strength. The dry-cured UCS specimens showed significantly higher strength than water-cured UCS specimens. The leaching of primary trace metals was also found to be well within the permissible limits as per EU (Council decision 1993/31/EC) and USEPA 2003.

In this research, naturally occurring black cotton soil (BCS) was used as a landfill liner to prevent leachate from interacting with groundwater. However, BCS forms cracks when exposed to excessive drying conditions, which might reduce the efficiency of liner material. In general, the addition of fibre can reduce the cracking behaviour of liner material. Massive quantities of waste tire production led to major environmental consequences (water, soil, and air) and posed a hazard to human life. For this cause, this work uses recycled tire fibres at 5, 10, and 15% dry weight proportions as reinforcing materials in BCS to improve liner efficacy. However, it is also essential to consider the leachate effect on liner material, which alters the various parameters of the liner. In this research work, fibre-mixed BCS was tested with two pore fluids (Sodium chloride and Calcium chloride) at 0 (DI Water) and 0.1 N concentrations to represent the leachate impact. This research investigates the impact of recycled tire fibres on the swelling, hydraulic, and strength behaviour of fibre-mixed BCS under the salt environment for landfill application. Results exhibited a drop in swelling pressures, swelling potentials, hydraulic conductivity, and peak strength values with a rise in tire fibre level. Moreover, pore fluids further influence these values, and the variation in results is more prominent with divalent pore fluid than with monovalent pore fluid. In conclusion, based on strength and hydraulic conductivity values, including the effect of pore fluids, test findings indicated that the optimal fibre content is 10%.

Sabkha soils are generally characterized by low shear strength and high compressibility. The water dissolves the salts which are the primary cementing agents. Therefore, stabilization methods that provide sustainable cementing substances utilizing Ordinary Portland Cement (OPC) and Waste Marble Powder (WMP) by-product for improving the properties of sabkha soils using deep soil mixing techniques are employed. A laboratory-scaled deep soil mixing procedure was developed to treat the sabkha soil. A binder consisting of waste marble powder and cement was employed to treat the soil. The objective of this study is to select the most efficient binder mix design in terms of optimum marble powder/cement ratio compared to cement only binder. Unconfined compressive strength and ultrasonic velocity pulse tests were conducted on the treated soil. For explanation of the treatment efficacy, microstructure analysis of treated samples was examined. The findings indicate that the cost-effective and environmentally friendly binder mix consisted of 70% cement and 30% waste marble powder with water/binder ratio 1.3. This particular mix contributed a significant improvement soil strength and facilitated the integration of columns.

The paper presents the research of lime-softening sludge geotechnical properties when using it to construct landfill liners. The physical and mechanical properties of the lime-softening sludge test results are shown. The particle size analysis of the sludge, the specific density of solids of the particles and the specific surface area as well as the consistency limits and the sludge’s compactibility have been determined in laboratory conditions. The tests of mechanical properties such as shear strength, uniaxial compressive strength and tensile strength have been carried out. A particular impact has been put on the sludge hydraulic permeability affected by the sludge moisture content and compaction. The synthetic analysis of the results revealed that the lime-softening sludge, in some determined conditions of building in and maintenance, meets the requirements for the landfill liners of the waste disposal sites and could successfully replace the natural soils in waste-landfill liners. A chart for constructing landfill liners made of sludge has been proposed.

Expansive soil is primarily impervious and shows swelling and shrinkage behavior when exposed to moisture fluctuation, making it incompatible with geomechanical applications. Recently, waste materials and fibers have been used to improve sustainable solutions in designing new soil reinforcing and stabilizing materials. In many rice-producing countries, rice husk (RH) is one of the most extensively available agricultural wastes. This study shows a detailed microstructural investigation of black cotton soil (BCS) stabilized with 3–15% rice husk ash (RHA) containing a high amount of amorphous silica needed for employing pozzolanic action in weak soils. The reorganized soil structure due to the treatment is researched through a series of microstructural tests, including scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and X-ray fluorescence (XRF). The microstructural analyses revealed that with the increase in RHA content, new compounds containing functional groups such as silanol and siloxanes (Si–OH and Si–O–Si–OH) got introduced into the BCS + RHA mixture, leading to an improved hydrophobic nature of the clay mixture. The XRD tests unveiled the amorphous nature of RHA. The XRF tests revealed an increment of 76% in the elemental composition of Silica (SiO2). The FTIR and SEM analyses reveal RHA’s specific functional groups and surface characteristics.

The bearing capacity or resistance of structures built on the expansive soil determines the stability of the soil. The structure fails due to the insufficient bearing capacity of the soil. As a solution for this, granular pile was installed in soft clays to overcome the problems like load bearing capacity, settlements, and swelling of the expansive soils. The laboratory test was conducted on expansive clay by varying the diameter of the stone column. The results revealed that bearing capacity increases, swell pressure decreases, and settlement decreases (79.13%) with the increase in the diameter of the stone column. The proposed granular pile method appears to be a practical means of ground improvement based on the results of a field test on black cotton soil.

India boasts one of the world’s largest transportation networks. For these infrastructure developments, natural quarried aggregates serve as the primary construction material, but the availability of suitable quality aggregates is becoming scarce. Consequently, it is vital to look for alternative, sustainable materials. On the other hand, large quantities of C&D waste are being generated as solid waste by the construction industry. These wastes can be segregated and recycled and can be used as an alternative geomaterial. Recycle Concrete Aggregates (RCA) are alternate geomaterials that can be reused to replace natural construction materials. In this study, an attempt has been made to study the effectiveness of using RCA as the compacted fill geomaterials. RCA that can be used as alternative geomaterials must be assessed to determine their applicability in pavement foundations. To evaluate the optimum dosage of RCA, various physical, mechanical and performance characteristics like granulometry, Atterberg limits, standard proctor compaction, dry and bulk densities, specific gravity, Los Angeles abrasion, crushing, impact, shear strength, CBR, compressive strength, bearing capacity and Resilient modulus, fatigue characteristics are evaluated. Replacing RCA in the compacted fill of a road pavement not only improves the desired properties but also reduces the environmental impact by reducing the amount of quarrying required (natural material).

Selenium (Se) is a rare metal found mainly in volcanic sediments. As Japan has many sulfide deposits, selenium is naturally widely distributed at low concentrations. Selenium exists in soil as soluble seleno-oxyanions, such as selenate [Se (VI)] and selenite [Se (IV)], which are highly toxic. The Japanese government has standards for soluble selenium concentrations in soil that can be achieved by water shielding or the addition of insolubilization agents. However, as these treatments leave selenium in the soil, it cannot be reused because of a risk of selenium re-elution. To solve this problem, we attempted to rapidly insolubilize soluble seleno-oxyanions in the soil by adding a bacterium, Stutzerimonas stutzeri NT-I, which reduces selenate [Se (VI)] through selenite [Se (IV)] to insoluble elemental selenium [Se (0)] and then elemental selenium to volatile dimethyl diselenide (DMDSe). We attempted purification of selenate-contaminated soil using S. stutzeri NT-I. Under optimal culture conditions, 46% of the initial selenate concentration was removed from the selenate-contaminated soil reducing Se elution below the designated standards within 72 h. These results indicate that bioremediation using S. stutzeri NT-I is effective for selenate-contaminated soil.

The accumulation of construction and demolition (C&D) waste in landfills is deemed a worldwide concern which is exacerbated by the impact of rapid urbanization and increased construction activities. The massive amount of waste disposal and increased demand for non-renewable virgin quarry materials such as natural sand triggers the urgent need to adopt various kinds of recycled materials in geotechnical fields, such as washed recycled sand (RS). Washed RS reviewed in this study is derived from C&D waste at a local washing plant in Melbourne, Victoria. Two types of washed RS were used as the target materials in this research based on their ranges of particle size: coarse recycled sand (CRS) and fine recycled sand (FRS). CRS and FRS have precisely the same source materials, while FRS experiences an extra round of the washing process. Extensive geotechnical laboratory tests were performed on an unbound stage, and the results indicated that both CRS and FRS exhibited similar geotechnical behavior with natural sand when used as pavement subgrade materials. Further, the geoenvironmental test suggested that the application of washed RS would not adversely impact the surrounding environment or human health. In addition, RS stabilized with 4% Portland Cement was found to effectively fulfill the relative requirement regulated by the local road authority through the unconfined compressive strength (UCS) test. This study highlighted that CRS and FRS could successfully substitute the role of natural sand required for pavement construction.

The Sand Compaction Pile (SCP) method is a technique of constructing well-compacted sand piles in the ground by repeatedly penetrating casing pipe with infilling material, pulling them out, and re-driving them into the ground. Sand and gravel are usually used as the infilling material for this SCP method, but even for liquefaction countermeasures, materials with the fines content of 5–15% are generally used. However, in recent years, it has become difficult to secure good quality materials (especially natural sand materials) that satisfy these conditions, and the use of recycled materials (recycled crushed stone and slag) has increased. This paper describes the history and transition of the use of SCP infilling materials as recycled materials and introduces a model test (shaking table test) conducted using infilling materials with some amount of fines and an actual case study (field test) of using recycled materials, and discusses the results of the tests.

The utilization of Paper Sludge Ash-Based Stabilizer (PSAS) presents an innovative method for incorporating eco-friendly materials derived from industrial processes into construction ventures. PSAS is crafted by immobilizing heavy metals found in the initial ash particles of paper sludge (PS), a byproduct stemming from the incineration of PS in paper mills. This study was undertaken to explore the impact of primary curing conditions and subsequent crumbling on the physical attributes, compaction properties, and strength characteristics of soils treated with PSAS. To draw comparisons, a parallel investigation was conducted on soils treated with Blast Furnace Cement Type B (BFCB) and Quick Lime (QL). Following a secondary curing phase in a saturated environment, cone index tests were performed on samples treated with PSAS, BFCB, and QL. The findings revealed that the cone indexes of samples subjected to primary curing exhibited variations, either higher or lower, in contrast to those without primary curing. These discrepancies were contingent on the primary curing environment and the duration of the curing period. These divergent trends were attributed to the interplay of “strength reduction due to crumbling” and “strength augmentation attributed to reduced water content during compaction.” In cases of PSAS-treated soils demonstrating gradual strength development, pre-compaction adjustment of water content in treated soils through primary curing proved to be a viable strategy. Furthermore, to minimize disparities between on-site observations and laboratory findings, we recommend aligning the curing conditions in the laboratory mixture design with real-world field conditions.

Beneficial reuse applications in geotechnical and geoenvironmental engineering have increased in recent decades due to performance benefits and improved sustainability in comparison to use of conventional virgin construction materials. Historically in the United States, large-scale beneficial reuse started with projects supported by the federal government. Availability of standards assists in identifying appropriate materials, appropriate procedures, and appropriate end uses overall providing consistency and confidence in reuse applications. The American Society for Testing and Materials (ASTM) International has a devoted subcommittee related to Geotechnics of Sustainable Construction that has supported development of several standards on recycling and reuse. Six different types of standards are supported by ASTM including terminology, classification, guide, specification, practice, and test method. Subcommittee D18.14 has developed and oversees a total of five active standards including a test method and four practices with additional standards in development. These standards provide the framework for effective and responsible construction practices and proper regulatory oversight for ensuring human and environmental health. Further development is needed for materials-specific and application-specific standards. Directions for strategic growth in the worldwide adoption of beneficial reuse for infrastructure construction applications include refining and expanding the extent of available standards to include life cycle and climate impacts analyses and improving international collaboration to develop best practices and standards.

Soil mixing method is a simple and economical operation in ground improvement. In recognizing carbon deduction during construction, it is important that the compressive strength, tensile strength, and bending moment can meet the requirement under working condition while reducing the amount of cement used. In this paper, we utilized Ottawa sand, Portland cement, and polypropylene (PP) fiber as the reinforced material to evaluate the mechanical behaviors of the material due to the addition of PP fibers. Specimen configurations include 5% cement addition by weight, water–cement ratios 1.0, PP fiber additions (0, 0.25%, 0.5%, and 1.0% by weight), and fiber length (6 and 12 mm). Unconfined compressive tests, Brazilian tests, and 3-point bending tests were performed to evaluate the effectiveness of fiber reinforcement through peak strength ratio, brittleness index, and toughness index. Test results indicated that at 28 curing days, the compressive strength, tensile strength, and bending moments capacity increased by 17%, 13%, and 28%, respectively. Furthermore, adding PP fibers increases the toughness so that the use of reinforcing steel can be reduced for diaphragm wall construction.

The functionality of pavement structure is significantly influenced by the subgrade properties. The saturation and desaturation of in-situ expansive subgrade contributes to pavement deteriorate through desiccation crack. To reduce these cracks, an expansive subgrade was polymerized and reinforced with sisal fibre, due to its promising prospect in pavement construction. This study investigated the cyclic crack restriction of polymerized expansive subgrade reinforced with 0.25%, 0.5%, 0.75%, and 1% of 30 mm sisal fibre. A series of zero swelling tests and resilient modulus tests were performed to explore the interactive effects of the polymer binder and sisal fibre on the expansive subgrade. The result revealed that the swelling stress of the expansive subgrade linearly decreases as the fibre content increases. Additionally, the resilient modulus of the treated subgrade increased as the fibre contents increases from 0% to 0.75% beyond which resilient strength decreased. The linear relationship between the increasing fibre content and the geopolymer binder mobilized the crack restrictions even at high cyclic stress and strain energy as the resilient modulus of the fabricated specimens increased. The test results confirmed that the polymer and clay minerals in the subgrade have a linear proportionality due to a complete polymerization reaction, as observed within the matrix of the fabricated specimens. The investigation confirmed that the coupling effects of geopolymer binder and sisal fibre significantly restricted cyclic cracks with an 88.1% decrease and 71.2% increase in swelling stress and resilient modulus, respectively. Whereas unreinforced polymerized subgrade failed to restrict the cracks at high cyclic stress and strain energy.

In Japan, the function of embankment bodies has been impaired in the aging of small earth dams because of the piping phenomenon of the small earth dams’ bodies caused by torrential rain and cracking caused by earthquakes. Therefore, countermeasures and repair works are being promoted at various places in Japan. Basically, natural impervious soil such as cohesive soil is used as a part of a small earth dam body. However, in recent years, the shortage of high-quality natural impervious soil and destruction of nature by excavation are becoming important issue. Therefore, this study focused on dehydrated cakes generated from the crushed stone manufacturing process as an alternative material to the impervious soil. The dehydrated cake is composed of fine particles and has low water permeability. Also, the dehydrated cake is required to be actively used in terms of effective utilization of waste material. Furthermore, this study added bentonite to dehydrated cakes to improve water impermeability and prevent piping, and it was investigated the effects of bentonite type and addition ratio on the swelling performance of dehydrated cake and hydraulic conductivity. As the results, the condition with 10% sodium-type bentonite added to the dehydrated cake had the highest swelling ratio and satisfied the required strength for construction machinery. Furthermore, the permeability required as an impervious material was confirmed, and the swelling of the bentonite reduced the size of the holes in the specimen.

Granite powder, a waste product of quarried granite rocks, is known for increasing the strength of cement-treated clay composites due to its pozzolanic reactivity. However, the durability of the established composites under seawater is unknown and needs to be assessed. Therefore, we investigated the durability under seawater exposure of cement-treated clay and slag-treated clay composites containing 0% and 30% granite powder and 8% cement or 30% steel slag to the dry mass of clay. The composites were exposed to seawater in the laboratory at 300C for 0, 28, and 63 days and tested their unconfined compressive strength (UCS) and chemical compositions using XRF. Consequently, after exposure, seawater samples were tested for their calcium and magnesium concentrations using a photometer. The UCS of cement-treated clay-granite powder and slag-treated clay-granite powder composites were higher than those of their respective control samples that did not contain granite powder for all the exposure days. The stress–strain curves show that the slag/cement-treated clay-stone power composites fail at higher stress and strain than their respective control samples. The cumulative Ca2+ elution was significantly higher in control samples than in the cement-treated clay-granite powder and slag-treated clay-granite powder composites. Conversely, the Mg2+ absorption was similar in the cement-treated clay-granite powder and slag-treated clay-granite powder composites and their respective control samples. The cement-treated clay-granite powder and slag-treated clay-granite powder composites were durable under seawater exposure and improved the UCS of cement-treated clay and slag-treated clay.

Prevention of liquefaction in sandy soils can be done by increasing the bearing capacity or density through the installation of micro-piles into the soil. Utilizing micro-pile on the liquefaction prone area is quite popular to increase the soil bearing capacity. So testing the use of eucalyptus pellita timber pile as an innovation in soil repair and strengthening engineering with the liquefaction potential is expected to increase the soil bearing capacity. In this research, eucalyptus pellita timber was used as micro-piles alternatives. This study aimed to determine the effect of increasing the bearing capacity of sandy soil due to the use of timber piles. The test method used was a laboratory test by conducting a percutaneous model test on a liquefied loose sandy soil with a seismic load for 37 s, with an acceleration of PGA = 0.3 g and frequency 0.78 Hz. The test results show that the eucalyptus pellita timber pile reinforcement given to loose sandy soil can provide additional bearing capacity, as shown from the test results of the timber pile reinforcement model being able to reduce settlements that occur due to seismic loads when compared to unreinforced soil, which is equal to 68%. The results verified the effectiveness of using timber piles as a strengthening material for loose sandy soils when compared to the unreinforced model test because the presence of timberen piles functions as a shear reinforcement of liquefied soil due to seismic loads, which in turn will lead to reduced settlements.

The waste materials from the manufacturing process were employed for the purpose of enhancing the strength of lateritic soil grade E, which exhibited the least suitable mechanical properties. The present study focused on the investigation of waste materials from the steel manufacturing process, namely electric arc furnace (EAF) slag and ladle furnace (LF) slag, as well as waste material from asphalt concrete plants, specifically asphalt waste dust (AWD). These waste materials were examined in relation to their potential utilization in combination with lateritic soil. The mixing ratio employed in this investigation was 10% by weight (wt%). A mixture of 5 wt% ordinary Portland cement was mixed with 90 wt% lateritic soil and 10 wt% asphalt waste dust to enhance the efficiency of lateritic soil stabilization. The efficiency of waste materials was evaluated by the California bearing ratio (CBR) test. The integration of EAF slag and LF slag, byproducts of the steel manufacturing process, significantly improved the CBR more than 5 times and 7 times, respectively, for EAF and LF mixes compared to natural lateritic soil. Furthermore, the CBR of lateritic soil blended with asphalt waste dust and Portland cement exhibited approximately 20 times higher than that of natural lateritic soil and cement-stabilized lateritic soil.

Soil with low bearing capacity is not able to support the construction on it so that a soil improvement method is needed to improve the soil structure. Soft soil stabilization has been carried out with various stabilizers, namely lime, cement, a combination of cement and fly ash, asphalt, and others, but this stabilizing agent is not environmentally friendly. Currently alternative environmentally friendly bio-stabilization is growing with the use of microorganisms (bacteria). The purpose of this study was to obtain the characteristics of the soft soil stabilized with bacteria by testing unconfined compression strength (UCS) and the direct shear test experimentally. The bacteria used were 3 days cultured bacillus subtilis bacteria with a composition of 4, 6, and 8% at optimum density conditions. The curing time was carried out for 7, 14, and 28 days after the preparation of the test object. The test results showed that the optimum bacteria content for stabilizing soft soil based on the test was obtained at 6%. At the curing time of 28 days, the unconfined compression strength value was 1073.83 kPa, and the elastic modulus was 368.88 kPa or an increase of 527% when compared to soil without bacteria stabilization. The soil shear stress was obtained at 194.66 kPa, an increase of 400% when compared to soil without bacteria stabilization.

Slag-clay mixtures, a mixture of steel slag and dredged clay generated from port improvement projects, have self-hardening properties. Therefore, the strength properties of slag-clay mixtures are evaluated in terms of unconfined compression strength, even at sites where confining pressure is applied. In this study, the consolidated and undrained triaxial compression tests were conducted on several slag-clay mixtures with different slag addition rates and cured them for 28 days, in order to investigate the relationship between the unconfined compression strength of the solidified slag-clay mixtures and the consolidated and undrained triaxial compression strength. The following findings were obtained from this experiment and discussion. The failure points obtained from the consolidated and undrained triaxial compression tests of the solidified slag-clay mixtures after 28 days of curing with unconfined compression strengths between 50 and 2000 kPa, when normalized by their consolidation yield stresses or unconfined compression strengths, were located into a narrow range, respectively. These relations are presented by two lines, and these are separated by the consolidation stress over consolidation yield stress and unconfined compression strength, respectively.

Use of mechanically stabilized earth (MSE) is known to improve the static and seismic performance of highway retaining walls, bridge abutments, dams, and levees. The stabilization of the earth is generally done by placing reinforcing elements such as metal strips, geosynthetic layers, or micro-piles in different layers of the backfill soil. The general convention is to prefer granular soils over cohesive soils as backfills due to their better drainage and lower shrinkage-swelling potentials. Nowadays, as an economic alternative, utilization of coal ash as a backfill material in MSE walls is being widely explored. Coal ash being a lightweight material with better drainage characteristics than cohesive soil poses several potential benefits in terms of static earth pressure, swelling issues, and dynamic inertia. However, the response of this coal-ash-filled MSE walls when subjected to dynamic loads is a topic that demands further investigation. The primary challenge is to select a constitutive model and define its parameters in a manner, by the virtue of which nonlinear and cyclic behavior of coal ash can be simulated. Moreover, since studies emphasizing the modeling of interaction between ash fill and reinforcing material are limited, there is scope for exploration in this direction. In this context, the present study focuses on developing a robust and reliable numerical model using discrete finite element approach which addresses these two issues for static and dynamic loading case. The model has been validated with results in existing literature. The performance of the wall has been assessed in terms of important response parameters such as lateral displacement, acceleration response, and the strain levels in the reinforcement layers at the end of the construction and during a seismic event.

Dredged soil (DS) is commonly considered as environmental waste and has poor geotechnical properties. It is necessary to conduct progressive research for this material which can be utilized. Using natural pozzolans (NP) to improve the geotechnical properties of dredged soil is considered an excellent stage toward sustainable engineering. This research objective assesses the effects of adding natural pozzolan to dredged soil over its CBR value. DS material was taken from sediment deposits in the Bilibili reservoir. According to the USCS classification system, this soil is classified as ML. Visually, this soil is light brown and dominated with fine grain size. The NP stabilizing agent has been dried, crushed, and filtered through a #200 sieve. The proportion of utilized NP was 3, 6, 9, and 12% by dry weight. The California bearing ratio (CBR) test was conducted to measure bearing capability. The CBR was tested in both un-soaked and soaked conditions. The curing time was applied for 7, 14, and 28 days to determine the impact of the additives’ chemical bonding. The results showed that the un-soaked CBR of stabilized DS increased by 2.1–3.2 times, and the soaked CBR of stabilized DS increased by 1.5–3.8 times for all curing periods. Based on these results, the stabilized DS material is suitable for road pavement embankment material.

This study aims to experimentally research the effect of steam curing on the compressive strength of concrete. The test variables included the compressive strength of concrete, two presteaming period (1.5 and 3 h), three curing temperatures (room temperature, 50 and 70 °C), and three blast furnace slag replacement ratios (0, 30, and 60%). Test results showed that with increase of the replacement ratio of blast furnace slag, it needed to increase the superplasticizer to achieve the required workability of concrete. At room temperature curing, the strength of control concrete was higher than that of concrete containing blast furnace slag before 28 days. With the increase of slag content, the growth rate of compressive strength tended to be slower. For the steam curing, the strength at 3 days was higher than that of the room temperature curing, and the strength at 28 days is lower than that of the room temperature curing. Longer presteaming period (3 h) and higher steam-curing temperature (70 °C) were helpful to the strength development of concrete with blast furnace slag at various ages. The concrete containing 30% blast furnace slag had the highest strength at all ages after 3 h presteaming period and 70 °C steam curing.

Utilizing supplementary cementitious materials to reduce cement usage is a promising solution to mitigate carbon emissions in the cement industry. Generally, the powder generated during the recycling process of concrete (i.e., recycled concrete powder, RCP) has an unfavorable effect on the performance of cementitious mixtures due to its low activity, but it can be improved by dehydration at high temperatures. In this study, RCP obtained in the crushing process of repeatedly recycled coarse aggregate concrete was thermally activated at various temperatures (200–800 °C), and its effect on the properties of cementitious mixtures as a partial cement replacement was discussed. The results showed that the properties of cementitious mixtures containing RCP heated at 200 °C and 400 °C did not show significant differences with those containing unheated RCP, whereas RCP activated at 600 °C and 800 °C contributed to the improvement of mechanical strength, drying shrinkage, and water absorption of cementitious mixtures than non-heated RCP, proving that thermal activation of RCP at these temperatures is effective for the utilization of repeatedly recycled concrete powder.

Toyama Prefecture has a thriving fishing and forestry industry, which generates a large amount of waste biomass in the manufacturing process. The authors have considered if we could make effective use of these biomass instead of throwing it away. Specifically, the authors have considered if we could make effective use of snow crab shells and Moso bamboo as recycled materials. On the other hand, as large earthquakes often occur in Japan, it is necessary to investigate the dynamic behavior of the biomass-mixed soil under earthquake conditions before it can actually be used. Therefore, the authors carried out the cyclic undrained triaxial test on soil in this study using a mixture of 10 and 20% of these biomasses by mass in the soil as it was mixed. The results showed that adding bamboo and crab powder to the masa soil increased the liquefaction strength. However, the liquefaction strength decreased as the mixing ratio of biomass increased. The author also considered that the reason for the increase in liquefaction strength was due to the shape and skeleton of the biomass and made microscopic observations using a SEM. The results showed that the biomass contained a large number of large and small fibrous T-bamboos and crab shells with rough and sharp H-surfaces. This is thought to have increased the stickiness of the material and made it more difficult to liquefy.

Sieved mixed wastes can be effectively used as geomaterials after solidification/stabilization treatment of the wastes using steelmaking slag and blast furnace slag. However, there is a concern that wood chips in the sieved mixed wastes will have a significant impact on the mechanical properties of the treated waste. Thus, this study conducted consolidated-drained triaxial compression tests on mixtures of wood chips and composite of a granular type steelmaking slag and a fine powder type blast furnace slag to elucidate the influence of wood chips on the mechanical properties of mixed wastes amended with slags. Fibrous and granular wood chips were used in this study. Wood chips-to-composite slag ratios from 0 to 67 vol.% were used for the tests. The specimens were cured from 0 to 1008 days. It was found that when the wood chip ratio was less than 10 vol.%, the shear strength and rigidity increased until 84 days of curing, but there was no further improvement thereafter, regardless of the wood chips used. In the case of 33 vol.% fibrous wood chips and 67 vol.% granular wood chips, the shear strength and rigidity hardly changed during 0–1008 days.

In recent years, construction and demolition wastes (CDW) have been used to produce recycled fine and coarse aggregates. However, the non-sorted presence of large quantities of crushed old concrete results in discontinuous particle gradation along with the presence of brick, mud, and wood in a portion of the CDW, renders the recycled aggregates unsuitable for recycled mortar. An effective optimization method involves the use of fly ash to replace a portion of the cement in recycled mortar to reduce the water–cement ratio and the mortar and brick interface transfer zone thickness. In this paper, we report the results of a comprehensive study on the feasibility of CDW as a fine aggregate for stone masonry. The effects of the fly ash content and natural sand substitution rate on the mechanical properties of the recycled mortar were quantified. Based on the experimental results, with an increase in the fly ash substitution rate, the 28-day compressive strength of the recycled mortar first increased and then decreased. When the substitution rate of fly ash was 20%, the strength reached a maximum value of 20.8 MPa. The results suggest that the fly ash substitution rate used in recycled mortar should be maintained at 20%, and the natural sand substitution rate should be within 20–30%.

Clinker ash in coal fly ash is known as a geomaterial superior to natural sand because of its light weight, high shear strength, and excellent permeability. However, the clinker ash content in coal fly ash is as low as 10%, and efficient utilization methods are needed. In this study, clinker ash is mixed with construction generated soil to expand its effective use, and physical tests, compaction tests, and triaxial compression tests are conducted to clarify its shear properties. The triaxial compression tests were conducted under both drained and undrained conditions. Construction generated soil, which is classified as organic clay, was used as the mixed soil. Since the construction generated soil did not contain soil particles larger than 19 mm in diameter, it was used in condition of original grain size distribution for a series of tests. The soil mixtures were made with dry mass ratios of 0:10, 3:7, 5:5, 7:3, and 10:0. The relationship between deviator stress and axial strain under undrained conditions shows that deviator stress moves upward as the clinker ash mixing ratio increases. The pore water pressure coefficient Af decreased as the clinker ash mixing ratio increased. This result depends on the dilatancy characteristics of clinker ash and construction generated soil mixtures. The maximum deviator stress also increased with increasing clinker ash mixing ratio, and the tendency of the increase depended on the drainage conditions even in the same clinker ash mixing ratio.

Over the last few years, the use of recycled waste materials in different construction activities has been increasing. The present study explores the suitability of steel slag, an industrial by-product, in geotechnical fill applications. Triaxial tests were conducted on specimens of 75 mm diameter and 150 mm height prepared at a relative density of 70% in dry and saturated conditions. The specimens were subjected to a strain rate of 1.25 mm/min during the testing. Test samples were reinforced with geogrid to enhance the strength of the material. The stress–strain behavior, effect of number of reinforcement layers, energy absorption capacity and particle breakage of the material were assessed. The findings indicated that steel slag has higher strength as compared to the commonly used geotechnical fill materials. The friction angle of slag in dry condition was found to be 50°, which reduced to 46° in saturated condition. Use of the geogrid improved the energy absorption capacity of steel slag. A maximum of 1.6 times improvement in the energy absorbing capacity was observed in the presence of geogrid. Moreover, a particle breakage factor of 0.058 was observed, which indicated negligible breakage of the particles.

The recycling of plastic waste has emerged as one of the most significant challenges impacting the environment. It is possible that their reuse as aggregates in the production of new construction materials will assist in the elimination of these plastic wastes, which would help to safeguard the environment and promote the attainment of sustainable development. Reusing non-biodegradable plastic waste materials can be an effective strategy for decreasing the use of natural resources for construction and lowering environmental hazards. This study, therefore, explores the feasibility of using recycled low-density polyethylene (LDPE) plastic as a partial replacement for fine aggregate in concrete. The purpose of this research is to evaluate LDPE concrete's mechanical and durability characteristics. It focuses mainly on compressive strength, split tensile strength (STS), flexural strength, and water absorption. Scanning electron microscope (SEM) analysis was used to investigate the microstructure of the specimens. The experimental work includes performance of M20 grade concrete and M50 grade concrete with varying percentage of LDPE aggregate as 0%, 5%, 10%, 15%, 20% and 0%, 1%, 2%, 3%, 4%, and 5% of the weight of fine aggregate, respectively. The replacement of sand with plastic waste showed a slight decrease in compressive strength when compared to the control normal mix. This type of concrete mix can be used in many applications such as highway medians, sub-bases for highway pavements, parking blocks, and various other structures where small strength reduction will not influence the performance a lot. It also helps reduce the self-weight of concrete in structures and helps conserve natural materials such as sand in good quantity.

Many geotechnical applications, such as landfill liners or covers, require an in-depth understanding of soil swelling and hydraulic conductivity. Bentonites and their amendments are often used for hydraulic barrier applications due to their distinctive properties. This research investigates the suitability of organically modified nanoclay as a bentonite amendment for hydraulic barrier applications. The performance of the nanoclay-bentonite mixture in the presence of different pollutants, such as heavy metals and organic contaminants, necessitates a thorough investigation. This work examines the effects of two heavy metals, lead and zinc, on the swelling properties and hydraulic conductivity of bentonite amended with nanoclay. Free swell test and oedometer tests were conducted on a number of bentonite and nanoclay-amended bentonite (10:90) samples under different concentrations, i.e. 0 ppm (DI water), 100 ppm, and 1000 ppm of lead and zinc. According to the findings, as heavy metal ion concentration rises, free swelling, swelling pressure, and swelling potential of both bentonite and organoclay-bentonite mixture drops. Even though the hydraulic conductivity rises for both the bentonite and nanoclay-amended bentonite, no samples exceeded the hydraulic conductivity criterion for landfill liners. Moreover, the addition of 10% nanoclay to bentonite minimizes the influence of heavy metals on the swelling and hydraulic properties of bentonite.

Sodium hydroxide-excited slag curing was used to stabilize phenol-contaminated soils with different contamination levels. Unconfined compressive strength and toxic leaching tests were carried out on solidified soil specimens of different time periods. In addition, X-ray diffraction (XRD) and scanning electron microscope (SEM) tests were performed on the contaminated soils solidified for 28 days. The test results showed that (1) The strength of the slag base polymer cured phenol-contaminated soil gradually increased with time and was influenced by the level of contamination. The higher the contamination level, the lower the strength of the cured soil. (2) After the contaminated soil was stabilized by alkali-excited slag geopolymer solidification, the leaching concentrations of phenol were significantly reduced. The leaching stabilization rates showed that the lower the contamination level, the higher the stabilization rate. (3) According to XRD and SEM–EDS, the mechanism of geopolymer curing stabilized composite contaminated soil was that geopolymer with a good cage structure adsorbed phenol.

Post-disaster materials and environmental management were investigated for a 500-year flood that occurred in Michigan, USA. The flooding was initiated by record-breaking rainfall over May 19–20, 2020, and was exacerbated by a succession of dam breaches and failures, resulting in catastrophic inundation of and damage to surrounding urban and rural areas. Analysis of debris generation and waste management practices indicated: (i) large quantities and varieties of debris generation; (ii) high uncertainties in model predictions and field estimation of debris quantity, composition, and spatial distribution; (iii) potential contamination of the floodwaters and debris from chemical manufacturing and wastewater treatment facilities; (iv) waste disposal facility access issues due to road and bridge closures; and (v) very limited public information regarding waste acceptance, capacity, and throughput for available landfills and reuse/recycling facilities. Improvements are required in pre-disaster preparedness; data collection, analysis, and modeling predictions; assessment of waste management infrastructure for post-disaster settings; and availability of sustainable alternatives for post-disaster waste management.