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This study evaluates the applicability of using a robust, novel, data-driven method in proposing surrogate models to predict the maximum dry unit weight, optimum moisture content, and California be...

The monitoring of water movement and transfer into the ground is very important for assessing mechanisms such as settlements, ground contamination, road collapse or landslides, to name a few. Soil moisture can be indirectly measured with different techniques. In this paper, a three-phase mixed α model of the soil dielectric constant is considered and the parameters are calculated considering a large database (experimental and from literature). Then, the physical meaning and interpretation of those parameters are described from the viewpoints of the soil index properties (i.e. soil type, dry density ρ d and clay content).

As it is commonly known, the estimation of physical and mechanical characteristics of rocks is very important issue in various geotechnical projects. The characteristics are mainly influenced by the microfabric-texture features of rocks. In this research, dry unit weight, effective porosity, point load index, Schmidt rebound hardness, uniaxial compressive strength, and texture coefficient were measured with the aim of correlating the physical and mechanical properties to the texture coefficient. For this purpose, a comprehensive laboratory testing program was conducted after collecting twenty sedimentary block samples including nine limestones and eleven mudstones, taken from Kalidromo (central Greece) in accordance with ASTM and ISRM standards. Also, mineralogical and petrographic properties, textural characteristics as well as X-ray diffractions were studied and the obtained results were statistically described and analysed. The maximum and minimum values of the texture coefficient were 0.13 and 0.50, respectively. The highest value was obtained for the rocks with a large amount of grains. Regression analyses were used to investigate the relationships between the texture coefficient and the engineering properties. Thus, empirical equations were developed and because of the good determination coefficients, they showed that all of the engineering properties were well correlated to the texture coefficient.

Soil stratum in Khon Kaen province, located in Northeast of Thailand, is well-known as a wind-deposited fine-grained soil (i.e. silty sand and silty clay). It is normally called “Loess or Khon Kaen Loess”. This soil in disturbed stage is usually extracted from the borrow pit and subsequently compacted for infrastructure applications. The compaction resulted in silty sand or silty clay aggregation with unpredictable properties. Although required for infrastructure design, studies on Khon Kaen Loess are limited. Thus, this research examines the compaction behavior and predicts soil parameters at various clay contents under a series of compaction energy on Khon Kaen Loess. The results showed that the maximum dry unit weights of samples could be related to the dry unit weight at plastic limit (PL), while the optimum water content (OWC) was correlated linearly with the PL. The samples with higher PL presented the higher OWC. In addition, the maximum dry unit weight and OWC of samples could be estimated using the developed equations validated with the other research results.

The current study aims to investigate the influence of the addition of fine materials on the engineering properties of silty sand soil. An intensive laboratory study of saturated and unsaturated silty sand soil treated with different percentages of fine materials of clayey soil (passing sieve #40 and ranging of 5, 10, 20, 40 and 80%) was investigated by conducting Oedometer and permeability tests. Unsaturated permeability and soil–water characteristics curve (SWCC) were also examined. Test results show that soil plasticity increases as the fine materials increase. The maximum dry unit weight (γdmax) increased up to 10% of fine materials then decreased, while the optimum moisture content (OMC) increased along with the increase of fine materials. One dimensional compression test results show that the fine materials influence the compression characteristics and the compression index of the soil samples increased with the increase of fine materials. In contrast, the saturated permeability sharply decreased as fine materials were increased. For higher percentages of fine content, the reduction in soil permeability becomes less significant. In addition, the unsaturated permeability decreases with fine materials and suction pressure increases. The effects of fine materials are more evident at lower suction pressures. Furthermore, the water holding capacity and air entry value increased with the addition of fine materials.

The compaction characteristics between reduced modified Proctor and modified Proctor tests have been compared. The results show that maximum dry unit weight values are comparable for both the tests but optimum moisture content values differ slightly more. For both the tests: optimum moisture content was found to correlate best with liquid limit, and the relationship for maximum dry unit weight with optimum moisture content was found to be almost the same. Since reduced modified Proctor requires less time and 40% less compaction energy as compared to modified Proctor test, it can be considered as a suitable alternative to the modified Proctor test.

This paper reports the strength and compressibility properties of sedimented ash beds treated with chemical columns. Sedimented model ash beds were prepared by simulating the natural sedimentation process in a laboratory environment and allowing them to undergo consolidation under the self-weight for a period of 30 days. Then, the ash beds were treated with three different configured chemical columns of sodium hydroxide (NaOH) with a concentration of 18 M for 60 days. After the 60 days of treatment, the in-situ dry unit weight, moisture content, bearing resistance, collapse potential, compressibility properties, and pore structure at different locations of the treated ash beds were examined. The contours of the bearing resistance were found to be bell-shaped with larger spreading towards the bottom end of the columns. The magnitude of the strength development was found to diminish rapidly with an increase in the radial distance from the column surface. After 60 days, the void ratio and collapse potential values in the column’s peripheral region of the ash beds treated with full, ½, and 1/4 columns were found to be 0.89, 0.93, and 0.95 and 0.75%, 0.89%, and 0.97%, respectively, compared to 1.64 and 7.46% of an untreated ash bed. These changes were attributed to the development and distribution of reaction products, which are functions of the column configuration and sampling location. The void ratio gradually increased with an increase in the radial distance from the chemical column. The decrease in void ratio was attributed to the blockage of the capillary pores by the reaction products. Primarily sodium- and calcium-based reaction products were observed along with hybrid compounds of sodium-calcium-based alumino-silicates. These reaction products encapsulated the ash particles within the matrix structure, thus modifying the bearing resistance, collapse potential, and compressibility properties of the sedimented ash beds. The morphology of the stabilized ash specimens showed a mixture of partially reacted ash particles, semi-crystalline structures, and reacted gel phase as the geopolymerization products.

A compacted claystone–bentonite mixture is proposed for use as a clay barrier. This research, in turn, focuses on the effects of bentonite mix on the permeability and shear strength of compacted claystone‒bentonite mixtures. The claystone used was obtained from the Banjarbakula landfill project, approximately 10 km from Banjarbaru, the South Kalimantan Government's Administrative Center, Indonesia. The bentonite used is commercially sold in Indonesia. The claystone was mixed with bentonite at a percentage of 5%, 10%, 15%, and 20% bentonite by dry-weight bases. The mixtures were compacted at a moisture content of 10%, 15%, and 20% to reach the dry unit weight of 16kN/m3‒19kN/m3. Permeability and unconfined compressive strength tests were performed in this study. The result showed that the permeability of mixtures decreases with increasing bentonite content. The addition of up to 20% bentonite to the mixture reduced the permeability by 4.5 times, as compared to the sample without bentonite. Moreover, the mixtures’ shear strength indicated by compressive strength and cohesion increased by increasing the bentonite content to 15%. The maximum shear strength obtained was three times higher than without bentonite. The mixtures’ permeability and shear strength were also significantly affected by the sample's density and moisture content. A percentage of 20% bentonite is recommended, considering the wide range of acceptability based on two criteria (i.e., permeability and shear strength).

The research presented aims to quantify the influence of the curing period (t), dry unit weight (γd), lime amount (L), and the addition of sodium chloride (NaCl) on the short- and long-term behaviors of coal fly ash – carbide lime blends. Strength and wet–dry durability tests were carried out for differing values of porosity (η), L, and curing time (t) on mixtures that either contained small amounts of NaCl or contained none. Addition of NaCl to the mixtures resulted in significant increase in early strength gain when compared to specimens without NaCl, which demand longer curing periods to reach similar strength values. The addition of NaCl to coal fly ash – carbide lime blends reduced the accumulated loss of mass (ALM) after 12 wet–dry brushing cycles for specimens at early stages of curing (about 50% for 7 days). Equivalence in the unconfined compressive strength (qu) and ALM(after 12 wet–dry cycles) between the specimens with and without NaCl is achieved in the long term. Finally, a variance analysis performed regarding qu and ALM results yielded that the order of importance of the controllable factors changed from t, NaCl addition, γd, and L for strength to γd, t, NaCl addition, and L for ALM(after 12 wet–dry cycles).

The present study is based on municipal solid waste incineration (MSWI) bottom ash stabilization when amended with cement and fiber. To simulate the effect of inclusion of cement and fibers on the behavior of MSWI bottom ash, numerous experiments were performed. The CBR test was considered as a basic parameter during the study. For CBR, a comparison was made among different test specimens under soaked and unsoaked conditions, with and without cement and fibers. The maximum dry unit weight of the bottom ash reduces, and moisture content rises due to the inclusion of cement and fiber. The results revealed that the relatively better combination was found to be highest gain of CBR value in case of 8% cement and 1% fiber. The study results also demonstrated that addition of fiber used to stabilize MSWI bottom ash reduces the stiffness as well as changes the behavior from brittle to ductile. Due to the free availability, such material can be used in compacted fills, embankments and road construction in very liberal manner. A multiple linear regression analysis of test results was carried out in order to develop a mathematical relationship to understand the intensity of different factors, i.e., MSWI bottom ash, cement content, fiber content, fiber length and curing period. The simulated model agreed reasonably with the experimental results.

In the present work, an experimental investigation was carried out to evaluate the radiation shielding performance of heavy-weight concrete mixtures prepared using different high-density coarse aggregates that included steel slag, steel shot, and iron ore. Normal-weight limestone aggregate was also used in control mixture as well as for partial replacement of the high-density aggregates in some of the heavy-weight concrete mixtures. Considering different combinations of the normal and high-density coarse aggregates and keeping cement content and water/cement ratio constant, a total of nineteen heavy-weight concrete mixtures were prepared and tested for their dry-density, compressive strength, and nuclear radiation response through gamma-ray intensity measurement. Except the control mixture containing normal-weight limestone aggregate, all eighteen heavy-weight concrete mixtures achieved 28-day dry unit weight in the acceptable range of 2600–3563 kg/m 3 . The compressive strength of the mixtures varied in the range of 26–45 MPa, all satisfying the requirements of a structural concrete. Radiation shielding performance was influenced by the unit weight of the concrete mixtures regardless of the type of coarse aggregates and the strength class of the concrete mixture. Based on the experimental data, correlations between indicator of the radiation shielding performance and unit-weight of concrete was obtained with a high degree of fit.

Quality control of road materials is important in road construction. Various methods have been developed based on the material dry unit weight or density. As a simple alternative method, this resea...

This paper presents the elaboration of equations controlling the unconfined compression strength (qu) of a silty soil treated with three types of cement. The equations were created under influence ...

Nanoparticles have been recently used in various applications due to their availability and justified costs. Thus, the effects of such materials on physical, chemical and mechanical properties of soils are of great interest to investigate. In this research, the effects of freeze-thaw cycles on specimens stabilized by nanoparticles are investigated. For this purpose, nano-SiO2 is used as an additive to fine-grained soils subjected up to nine freeze-thaw cycles. Laboratory tests including standard Proctor, Atterberg limits and unconfined compression tests (UCTs) have been conducted on a clayey soil mixed with nano-SiO2. The samples were also cured for up to 42 days. The results show that when the clayey soil is stabilized with nano-SiO2, the optimum moisture content, liquid limit (LL) and plastic limit (PL) increase, while the maximum dry unit weight and PI decrease. An increase of nano-SiO2 up to an optimal of 2% and curing time up to 42 days improves the unconfined compressive strength (UCS) by about 63%. In addition, the increase in nano-SiO2 leads to brittle behavior of the specimens. Moreover, the freeze-thaw cycle decreases the UCS of the specimens. However, a descending trend for strength is observed in nano-SiO2 stabilized specimens compared with untreated clay. After nine freeze-thaw cycles, the strength of untreated and treated soil with 2% nano-SiO2 decrease by about 64% and 42%, respectively. Also, with increasing the freeze-thaw cycles, stabilized specimens exhibit more ductility.

Known challenges exist with maximum (γdmax) and minimum (γdmin) dry unit weight measurements; the respective dry unit weight results depend very much on the method or standard used. A laboratory testing programme was completed to systematically determine and compare γdmax and γdmin values derived for six different sand types by using different methods. The tested sands contained a wide variety of mineralogical and fines contents. The γdmax and γdmin determinations were performed according to the following methods: British Standards Institution (BS) standards; American Society for Testing and Materials (ASTM) standards; Deutsches Institut für Normung (DIN) standards; Dansk Geoteknisk Forening (DGF) guidelines; Norwegian Geotechnical Institute (NGI), Geolabs, and Fugro proprietary methods. Differences in testing procedures, material requirements for testing, and the effects of soil degradation during testing introduce challenges and large differences in γdmax and γdmin values for each of the six sand types were observed. Therefore, it is concluded that there is a need for the development of new standards for a robust determination of γdmax and γdmin values. Specifically, a standard for determining γdmax is required to consistently obtain results at the upper bound of dry unit weight values for the likely range of sands — without crushing the sand grains.

Although some discarded tires are reused in various applications, a considerable number end up in landfills, where they pose diverse environmental problems. Waste tires that are shredded to produce tire-derived aggregates (TDA) can be reused in geotechnical engineering applications. Many studies have already been conducted to examine the behavior of pure TDA and soil-TDA mixtures. However, few studies have investigated the behavior of larger TDA particles, 20 to 75 mm in size, mixed with various types of soil at percentages ranging from 0% to 100%. In this study, TDA was mixed with gravelly, sandy, and clayey soils to determine the optimum soil-TDA mixtures for each soil type. A large-scale direct shear box (305 mm × 305 mm × 220 mm) was used, and the mixtures were examined with a series of direct shear tests at confining pressures of 50.1, 98.8, and 196.4 kPa. The test results indicated that the addition of TDA to the considered soils significantly reduces the dry unit weight, making the mixtures attractive for applications requiring lightweight fill materials. It was found that adding TDA to gravel decreases the shear resistance for all considered TDA contents. On the contrary, adding up to 10% TDA by weight to the sandy or clayey soils was found to increase the shear resistance of the mixtures. Adding up to 10% TDA by weight to the clayey soil also sharply increased the angle of internal friction from 18.8° to 32.3°. Moreover, it was also found that the addition of 25% TDA by weight to the gravelly or sandy soils can reduce the lateral earth pressure on buried structures by up to 20%. In comparison, adding 10% TDA to clay resulted in a 36% reduction in the lateral earth pressure.

This paper presents the results of pressure settlement behavior of strip footing resting on poorly graded sand reinforced with tire strips in layers to improve the bearing capacity. The tire strips of length 3B, 4B and 5B (B = width of footing) and 70 mm width were used. The tire strips were placed at 0.4B, 0.6B, and 0.8B from the base of the footing. The tests were carried at 14, 14.2, and 14.3 kN/m3 dry unit weight of sand. From this investigation, it was observed that the bearing capacity of reinforced soil increases with the increase in length of reinforcement, depth of reinforcement, and dry unit weight of sand. With increase in the depth of reinforcement layer, length of reinforcement and number of layer significant reduction in the settlement of sand was observed. It was observed that the settlement reduction effect was higher at higher unit weights.

Constructing embankments or multi-story structures can induce lateral soil movement especially for cohesionless soil due to its weak structure. In case of having these constructions near an existing pile group, damage can occur to these piles due to the passive loads induced by the soil movement especially when these loads exceed the capacity of the piles. In the current study, the performance of the existing flexible (2 × 1) pile group installed in cohesionless soil has been investigated experimentally under the effect of lateral soil movement induced by a nearby embankment. To simulate the cohesionless soil, a sandy soil having a dry unit weight of 13.5 kN/m3 has been used in this study. While an aluminum pipe with an outer diameter of 10 mm and a length of 500 mm has been used to simulate the piles. An embedded length (Le) of 420 mm has been adopted in this study to ensure the flexible behavior for the piles. The embankment loads have been applied at distances of 2.5D, 5D, and 10D from the edge of the pile. The results show that the soil reaction has decreased with increasing the distance between the edge of the piles and the embankment due to the reduction of soil movement pressure. The maximum soil reaction has decreased by (25–33)% in the loaded pile group (LG) and by (50–60)% in the unloaded pile group (UG) with increasing the distance from 2.5D to 10D, respectively.

Instantaneous results for compaction control can be obtained using the nuclear gage. The Humboldt GeoGauge is a relatively new and promising instrument that is portable, that also provides instantaneous results and that does not require handling of radioactive materials. Unlike the nuclear gage, which yields the soil unit weight and water content, the GeoGauge yields soil stiffness corresponding to very low strains. For compacted partly saturated soils, the dry unit weight can be related to stiffness and water content. This relationship is derived herein. Using this relationship, measured values of stiffness and water content can then be used to predict the dry unit weight in the field. Predicted and measured values of dry unit weight are compared for a tropical soil in Hawaii. For the covering abstract see ITRD E118503.

Anisotropy of hydraulic conductivity is an important parameter controlling fluid movement in municipal solid waste (MSW) landfills, while measurements of anisotropy are rare. In this study, a laboratory-scale enhanced reactor was built to create MSW samples with different degrees of degradation. Vertical and horizontal hydraulic conductivities of these samples were measured in a self-designed permeameter to study the effects of compression and degradation on anisotropy of MSW. CT scanning was performed to observe the internal pore-structure of MSW under compression. A prediction model of anisotropy under compression was established. It was found that as degradation time increased from 0 month to 18 months, the dry mass percent of 0D particles increased from 12.3% to 38.8%, while 2D particles content decreased from 78.7% to 47.2%. As vertical stress increased from 50 kPa to 400 kPa, dry unit weight (γd) increased from 3.26 kN/m3 to 5.51 kN/m3, anisotropy (A) increased from 1.26 to 5.17. It was because that the size and continuity of pores decreased and the angle of pore arrangement tended to be horizontal as the vertical stress increased. The relation between anisotropy and vertical stress could be well fitted with the prediction model. When degradation time increased from 0 month to 18 months, A decreased linearly from 5.02 to 2.75 due to the decreasing content of 2D particles. Anisotropy also decreased with the decreasing C/L. Compression has much greater influence on waste anisotropy than that of degradation. Anisotropy of MSW at different depths of landfills could be determined based on the trend lines in this study.

This paper reports the experimental results of using two chemical additives to enhance the properties of marine clay collected from Vypin, Cochin area. Modifications in properties of marine clay by lime are investigated to compare the nano-silica particles’ effect in mechanical properties of clay. The engineering properties studied included Atterberg limits, maximum dry unit weight, optimum moisture content and unconfined compressive strength. Lime to soil ratios of 3, 4 and 5% were used. Nano-silica used for the study varied from 0.5, 0.8 and 1%. Atterberg limits variation and unconfined compressive strength variation were evaluated for the curing period of 3, 7, 14 and 28 days. Strength is enhanced three times for amended clay with nano-silica. Optimum lime content for lime stabilized clay was obtained as 4% and nano-silica as 0.8%. Plasticity characteristics are remarkably modified in the lime-amended clay compared to nano-silica additive. Unconfined compressive strength improvement shows similar variations for both nano-silica and lime.

The reuse of waste material is becoming an emerging thrust area in Civil Engineering. Crumb rubber produced in abundant worldwide is reused in concrete, pavements, sports field, etc. The influence of crumb rubber, when mixed with highly compressible and inorganic clay, shows significant influence in its compaction characteristics under light compaction. Various proportions of crumb rubber were added namely 10,15,20,30,40 and 50% by weight and tested to understand its compaction characteristics. The behaviour of wet and dry of optimum side of modified soil with various percentages of crumb rubber was discussed. A model is generated to calculate the maximum dry density of the modified clay.