Compaction Characteristics Research Articles

Effects of the application of anaerobically digested sewage sludge on the consistency limits and compaction characteristics of differently textured soils

Notwithstanding their beneficial characteristics, the agricultural utilization of organic wastes may have an adverse effect on soil properties if used improperly. To evaluate proper use, a laboratory study was conducted to investigate the effects of different sewage sludge application doses (0, 2, 4, and 8% weight/weight) on the consistency limits and the compaction characteristics of three differently textured soils. The application of sewage sludge significantly improved the consistency limits and reduced the compactibility. The efficacy depended on the amount applied. The rates of increase in liquid limit (LL) values at 8% sewage sludge were 58.7% for sandy loam, 43.4% for loam, and 16.2% for clay soil. As the application dose increased, the optimum moisture content (OMC) values increased and the maximum dry bulk density (MBD) values decreased. The highest application dose decreased the MBD by 9.5% in sandy loam, by 6.5% in loam, and by 13.7% in clay-textured soils. The rates of increase in OMC values were 73.4%, 53.8%, and 27.1%, for sandy loam, loam, and clay, respectively. The results presented in this study clearly indicated that the application of sewage sludge made the soils more resistant to mechanical forces, since the increase in the proportion of OMC over LL and PL implied that the soil was easier to till at higher moisture contents without any deformation, which also resulted in a higher workable range.

The Effect of Mineral Composition and Quantity of Fines on the Atterberg Limits and Compaction Characteristics of Soils

The Effect of Mineral Composition and Quantity of Fines on the Atterberg Limits and Compaction Characteristics of Soils

Enhancing image security and privacy with hybrid double random phase encoding, lorenz maps, and compressed sensing

The resilient and secure image encryption method presented in this research combines the benefits of Lorenz maps and double random phase encoding (DRPE) with compressed sensing. The suggested method attempts to maximize the use of storage resources while maintaining the security and integrity of sensitive image data during transmission and storage. Utilizing the energy compaction characteristics of the original image, compressed sensing with discrete cosine transform (DCT) is used in the encryption process to effectively represent and transmit the encrypted data. Lorenz maps are also used to create double random phase masks, adding high unpredictability and key sensitivity to strengthen the encryption scheme’s security. Utilizing a variety of performance indicators, including the PSNR, NPCR, MSE, and SSIM, experimental investigations demonstrate the usefulness of the suggested strategy.

Influence of discharge energy on electromagnetic compaction characteristics of copper powders with same compression amount

Electromagnetic powder compaction technology is an effective method for producing high density and strength parts. In this work, the influence of discharge energy on the electromagnetic compaction characteristics of copper powders with same compression amount was studied through experiment investigation and numerical simulation. The finite element simulation, micro morphology observation, and compressive strength testing were conducted. Results showed that the propagation direction of stress was 45° from top to bottom of compacts. At 7–9 kJ, there was a turning phenomenon in the direction of stress propagation at the upper edge position due to the restriction of shim. As the discharge energy increased, the pores on the upper end face shifted towards reduction and concentration, ultimately forming local defects with large pores. This method could be used to improve the compaction quality of the local position of compacts. The compressive strength of compacts also increased gradually and then almost linearly, and the maximum value was 164.07 MPa. The relationships between volume strain and compaction time were obtained, R-square exceeded 0.9997 under different discharge energies, indicating high reliability.

Influence of fibres on the resilient modulus and expansion of clayey subgrade soils

ABSTRACT Expansive clayey soils at the subgrade level of roads and highways in different cities can affect the performance and durability of pavements. This increases the need for maintenance and conservation work, leading to higher operating costs. Traditionally, clayey soils are stabilised by adding lime or cement. However, the handling and use of these materials are restricted in some Latin American countries due to illegal drug production, and obtaining high-quality materials from distant sources can be impractical. The goal of this study is to determine the effectiveness of incorporating fibres in improving the performance of expansive clayey subgrade soils. To achieve this goal, resilient modulus tests and measurements of compacted soil expansion were performed. Two types of fibres were selected for this study: natural Ichu fibre, which is common in the Peruvian Andes, and polypropylene fibre. The soil used was a high-plasticity clay from the city of Pucallpa, to which varying percentages of fibres were incorporated (0.25%, 0.5% and 1%). The samples were prepared with a gyratory compactor to achieve their maximum dry density as obtained with the standard compaction effort. The results indicated that the incorporation of fibres improved the value of the resilient modulus while significantly reducing soil swelling.

Enhancing the Compaction Characteristics of Peat Soil through Ground Granulated Blast Furnace Slag (GGBS) Stabilisation

Peat soil is renowned for its compressibility problem that can give rise to issues such as ground settlement, particularly within the spectrum of construction endeavours. Conversely, the implementation of chemical stabilisation, involving the incorporation of suitable additives, is contemplated prior to commencing construction activities. Ground Granulated Blast Furnace Slag (GGBS), which is a byproduct of the iron and steel industry, stands out as a prominent additive that can augment the engineering attributes of peat soil. This investigation focuses on the compaction characteristics of peat soil treated with varying proportions of GGBS, as evaluated through the Modified Proctor test. It involved examining the impact of diverse GGBS additions on the liquid limit of peat soil. The findings showed that the introduction of GGBS yielded a substantial reduction in the liquid limit of peat soil, signifying an elevated susceptibility to moisture and an increase in plasticity. Moreover, the incorporation of GGBS into peat soil prompted an increase in its Maximum Dry Density (MDD) and a reduction in its Optimum Moisture Content (OMC). Notably, the peak MDD, registering at 1000 kg/m³, was achieved at a GGBS content of 50%, marking the highest value observed in this study. The OMC values further indicated the lowest moisture content, standing at 29%, with the addition of 25% GGBS to the peat soil. These outcomes convincingly advocate that the utilisation of GGBS in treating peat soil engenders positive enhancement in its compaction characteristics, specifically pertaining to MDD and OMC. Such enhancement in engineering properties holds promising implications for potential stability.

Evaluating the Potential of Multi-Walled Carbon Nanotube-Modified Clay as a Landfill Liner Material.

In this paper, the feasibility of multi-walled carbon nanotube (MWCNT)-modified clay as a landfill liner material is investigated. Experiments were conducted on the modified clay with 0.5%, 1%, and 2% MWCNTs. The effects of the MWCNTs on the compaction characteristics, permeability coefficient, stress-strain curve, peak deviation stress, shear strength parameters (internal friction angle and cohesion), microstructures, and adsorption performance of the clay were analyzed. The results showed that the optimum moisture content (OMC) increased from 16.15% to 18.89%, and the maximum dry density (MDD) decreased from 1.79 g/cm3 to 1.72 g/cm3 with the increase in MWCNTs. The permeability coefficients firstly fell and then gradually rose as the MWCNTs increased; the minimum permeability coefficient was 8.62 × 10-9 cm/s. The MWCNTs can also effectively increase the peak deviation stress of the clay, and at the maximum level, the peak deviation stress was increased by 286%. SEM images were processed using the Pore and Crack Analysis System (PCAS), and the results showed that the appropriate amount of MWCNTs could fill the pores and strengthen the clay structure. The effect of the MWCNT-modified clay on the adsorption performance of common heavy metal ions Cd2+, Mn2+ and Cu2+ in landfill leachate was analyzed by batch adsorption tests. The maximum adsorption capacities (Qmax) of Cu2+, Cd2+ and Mn2+ in the 2% MWCNT-modified clay were, respectively, 41.67 mg/g, 18.69 mg/g, and 4.97 mg/g. Compared with the clay samples without MWCNTs, the adsorption properties of Cu2+, Cd2+, and Mn2+ were increased by 228%, 124%, and 202%, respectively. Overall, the results suggest that MWCNT-modified clays have the potential to be suitable barrier materials for the construction of landfills.

Computer vision-aided DEM study on the compaction characteristics of graded subgrade filler considering realistic coarse particle shapes

The compaction quality of subgrade filler strongly affects subgrade settlement. The main objective of this research is to analyze the macro- and micro-mechanical compaction characteristics of subgrade filler based on the real shape of coarse particles. First, an improved Viola–Jones algorithm is employed to establish a digitalized 2D particle database for coarse particle shape evaluation and discrete modeling purposes of subgrade filler. Shape indexes of 2D subgrade filler are then computed and statistically analyzed. Finally, numerical simulations are performed to quantitatively investigate the effects of the aspect ratio (AR) and interparticle friction coefficient (μ) on the macro- and micro-mechanical compaction characteristics of subgrade filler based on the discrete element method (DEM). The results show that with the increasing AR, the coarse particles are narrower, leading to the increasing movement of fine particles during compaction, which indicates that it is difficult for slender coarse particles to inhibit the migration of fine particles. Moreover, the average displacement of particles is strongly influenced by the AR, indicating that their occlusion under power relies on particle shapes. The displacement and velocity of fine particles are much greater than those of the coarse particles, which shows that compaction is primarily a migration of fine particles. Under the cyclic load, the interparticle friction coefficient μ has little effect on the internal structure of the sample; under the quasi-static loads, however, the increase in μ will lead to a significant increase in the porosity of the sample. This study could not only provide a novel approach to investigate the compaction mechanism but also establish a new theoretical basis for the evaluation of intelligent subgrade compaction.

Characterization of black cotton soil by using granulated blast furnace slags

Soil stabilization is the best way to enhance the characteristics of low-quality soil. The properties may include, permeability, compressibility, strength, durability, etc. It is required when there is a need for construction on the poor sub-soils that are not suitable for that particular construction. Black cotton soil (BC) has a high clay content and is also considered as compressible soil with shrinkage and swelling characteristics and a constrained bearing capacity. It expands during the rainy season due to water absorption and contracts during the summer, which gives rise to serious structural deterioration. This study targets to stabilize this black cotton soil using ground granulated blast furnace slags (GGBS). It is a by-product of iron found in the blast furnace. It is extremely cementitious and contains a large amount of calcium silicate hydrates that increase its durability, strength, and appearance. In this study, GGBS is used at different percentages such as 5 %, 10 %, 15 %, 20 % and 25 %. Sodium hydroxide is also added in various dosages from 0.5 M, 1 M, 2 M, 4 M and 6 M. The major goal of this study is to investigate how GGBS affects the engineering parameters such as Atterberg’s limit, differential free swell (DFS), Compaction characteristics (i.e., maximum dry density (MDD) and optimum moisture content (OMC)) and unconfined compressive strength (UCS). The durability characteristics of soil-GGBS mixtures are also studied. Results show that as compared to virgin soil, adding 25 % of GGBS to BC soil resulted in an increase in MDD of around 16.5 % and a decrease in OMC of about 29 %. Further, it is also found that compared to (Soil + 20 % GGBS), the UCS value of the (Soil + 20 % GGBS + 4 M NaOH) mixture increased by roughly 36.5 %. Finally, the optimum concentration of GGBS content is found as 20 % while treated with 4 M NaOH solution.

A neural network filter based high-sensitive MIR CO2 sensor

A low-power consumption, small-size and high measurement sensitivity mid-infrared (MIR) carbon dioxide (CO2) sensor was developed based on wavelength modulation spectroscopy (WMS) technology, utilizing a mid-infrared distributed feedback interband cascade laser (DFB-ICL) operating around 2682 nm. The sensor incorporated two key components, a home-made multi-pass gas cell with base length of 10 cm achieving 1.5 m optical path and a highly integrated FPGA board, which were used to reduce the size of the sensor. A novel second harmonic-neural network filter (SH-NNF) was also proposed and implemented in this sensor. The sensor’s performance was evaluated through a 20 mins continuous experiment using calibrated gas with 500 ppm concentration. The results, before and after SH-NNF, demonstrated an improvement in sensitivity and detection precision from 1.68 ppm (1 σ) to 1.17 ppm and from 2.14 ppm to 1.45 ppm, respectively. The optimum limit of detection of 0.392 ppm with integration time of 218 s was obtained. The ppm detection and compact characteristics of the developed MIR sensor show its potential for detecting CO2 in the ambient air.

Effect of design parameters on degree of blending and performance of recycled hot-mix asphalt incorporating fine reclaimed asphalt pavement particles

Due to the rich binder content and high economic benefits of fine reclaimed asphalt pavement (RAP) particle, more and more attention has been paid to the effective design of recycled hot-mix asphalt (HMA) incorporating this material. This research explored the effect of design parameters on degree of blending (DoB) and performance of recycled HMAs incorporating fine RAP particles. Six groups of mixes were designed, including one no blending group, four experimental groups, and one full blending group. The different parameters of preheating temperature, compaction effort, asphalt content (AC), and blending duration, were involved in this research. It can be found that the recycled HMAs incorporating fine RAP particles under the traditional design proved to the risks in water stability and low-temperature performance. By rising the preheating temperature, decreasing compaction effort and increasing AC, or extending the blending duration, more RAP binder would be activated and blended with the virgin binder, and the poor rheological performance of recycled HMAs can be restored. The different design parameters have different effects on the performance. Besides, the actual contribution of DoB to performance was quantified. With an increase in DoB by 10%, the tensile strength ratio, shear strength, fracture energy, fracture strength, and abrasion loss percentage of recycled mixes can improve by around 15%∼28%, 0.15–0.34 MPa, 180–1969 J·m2, 0.25–0.34 MPa, and 7–18%, respectively. In addition, design incorporating fine RAP particles generally can bring significant advantages in energy consumption and CO2 emission.

Qu-omics elucidates the formation and spatio-temporal differentiation mechanism underlying the microecology of high temperature Daqu

Even if fermented in the same qu-room, Daqu will form various microecologies. A gradual differentiation of microbial population niches was observed within different qu-layers, manifesting as variations in the abundance of dominant microorganisms including Bacillus, Saccharopolyspora, Weissella, Kroppenstedtia, Thermoascus, Thermomyces, Saccharomycopsis, and Rasamsonia. Moreover, distinctions were observed in the functional expression of microorganisms, including Aspergillus, Virgibacillus, Oceanobacillus, and Neurospora. The community in middle layer Daqu exhibited characteristics of high compactness and niche diversity, which facilitated efficient substrate utilization. During the initial phase, the upper Daqu community demonstrated heightened activity. However, in the middle and lower layers, fungi and bacteria respectively exhibited greater functional expression. The key environmental factors regulating the assembly of communities in the upper and middle layers were pH and temperature, respectively, and the lower was moisture and acidity. Notably, deterministic assembly exerted a stronger influence on fungi.

Analysis of alkali leaching mechanism on as-built cement concrete bridge deck pavement: View from the perspective of mesostructure characteristics

The emergence of a new distress mode, known as alkali leaching, has been increasingly reported in the cement concrete bridge deck pavement (CCBDP). The presence of defects in the pavement structure causes the accumulation and movement of alkaline solution. The examination of the internal pore features of deteriorated pavements is advantageous in order to comprehensively reveal the mechanism of alkali leaching on CCBDP. The present research focuses on analyzing the mesostructure of alkali leaching specimens obtained from distressed pavement. This analysis is conducted using X-Ray Computed Tomography (X-ray CT) and digital image processing (DIP) technologies. In order to assess the correlation between pore characteristics and alkali leaching, a parameter known as the critical pressure difference (CPD) is defined and calculated to quantify the leaching ability. The results show that alkali leaching cores (ALC) have a higher number of voids compared to Normal Cores (NC), particularly for voids of larger volume. Inadequate compaction effort induces vertical connectivity of voids in the alkali leaching pavements, thereby impeding the movement of alkaline solution. A sensitive porosity interval around 4.5 ∼ 5.5 % is found, the DGAC with larger porosity will easily occur leaching phenomenon in the certain CPD section. The correlation between the porosity and the CPD is also identified, indicating that the porosity is the main inherent factor in alkali leaching.

A Low-Cost Microfluidic and Optically Transparent Water Antenna with Frequency-Tuning Characteristics.

In this study, a novel microfluidic frequency reconfigurable and optically transparent water antenna is designed using three-dimensional (3D) printing technology. The proposed antenna consists of three distinct parts, including a circularly shaped distilled water ground, a sea water-based circular segmented radiator, and a circularly shaped distilled water-based load, all ingeniously constructed from transparent resin material. The presented antenna is excited by a disk-loaded probe. The frequency of the antenna can be easily tuned by filling and emptying/evacuating sea water from the multisegmented radiator. The radiator consists of three segments with different radii, and each segment has a different resonant frequency. When the radiator is filled, the antenna resonates at the frequency of the segment that is filled. When all the radiator segments are filled, the antenna operates at the resonant frequency of 2.4 GHz and possesses an impedance bandwidth of 1.05 GHz (40%) in the range of 2.10-3.15 GHz. By filling different radiator segments, the frequency could be tuned from 2.4 to 2.6 GHz. In addition to the frequency-switching characteristics, the proposed antenna exhibits high simulated radiation efficiency (with a peak performance reaching 95%) and attains a maximum realized gain of 3.8 dBi at 2.9 GHz. The proposed antenna integrates water as its predominant constituent, which is easily available, thereby achieving cost-effectiveness, compactness, and transparency characteristics; it also has the potential to be utilized in future applications, involving transparent and flexible electronics.

Analysis of the difference of test methods for laboratory compaction characteristics of soil

For earthworks (house foundation, road, ....), the degree of compaction is the basic quality factor to ensure long-term stability and economic efficiency of the project. The higher the degree of compaction, the greater the building load capacity. However, the degree of compaction of the structure depends not only on the material, but also on equipment and compaction energy. For each type of material, the degree of compaction is expressed as the ratio of the actual applied dry volumetric mass achieved to the maximum dry volumetric mass of the same soil determined by the standard compaction test. standard in the laboratory. Therefore, laboratory tests to determine the standard compaction value must be studied to suit the compaction construction technology. Standard soil compaction in the laboratory is determined based on two main compaction devices: the standard Proctor device and the improved Proctor device.

Evaluation of mortar film thickness of dry process crumb rubber modified warm mix asphalt concrete utilizing 2-dimensional images

Asphalt mortar film thickness and its distribution are accepted to be strong parameters that affect the durability and performance of asphalt mixtures. This study focuses on the effects of the Warm Mix Asphalt (WMA) additive, production temperatures, and compaction effort on the distribution of mortar film thickness in dry process crumb rubber modified mixtures. Utilizing image analysis, not only mortar film thickness distribution but also its distribution for each aggregate size fraction was analyzed. It is revealed that the difference in mixture preparation procedures and aggregate size fractions significantly affects the distribution and variation of mortar film thickness. Moreover, to relate between cracking and the mortar film thickness, indirect tensile strength tests are performed at three different temperatures. A good correlation was only built between cracking resistance and average mortar film thickness at −10 °C. Therefore, it can be concluded that the mortar film thickness cannot be solely used as an indicator of performance. However, it can be still generalized that thicker and variable mortar film thickness weakens the aggregate interlock and low-temperature cracking resistance.

Spatial modeling of geotechnical soil parameters: Integrating ground-based data, RS technique, spatial statistics and GWR model

Ensuring the availability of a cost-effective method to predict soil behavior is imperative for newly developed construction sites. This research aims to create a model that can estimate the spatial distribution of soil properties and compaction characteristics using the Inverse Distance Weighting (IDW) and Geographic Weighted Regression (GWR) methods within the study area, specifically in Koya city, situated in Erbil, Iraq. To determine these soil parameters, 27 soil samples were collected from the fields based on stratified random sampling, and then tested and analyzed in the laboratory. The IDW spatial interpolation technique and GWR method were then used to create a spatial distribution map of soil properties and compaction characteristics. In the GWR model, the calculated soil properties and compaction characteristics served as the dependent variable, while the Modified Normalized Difference Water Index (MNDWI) derived from the Landsat8 satellite image was the independent variable. This process resulted in a spatial distribution map showing the soil properties and compaction characteristics. The results indicated a strong correlation between the MNDWI water indexes and various soil parameters, including water content, liquid limit, plastic limit, optimum moisture content, and maximum dry density, with respective coefficient of determination (R2) values of 0.91, 0.97, 0.98, 0.95, and 0.96. Additionally, the assessment of the precision in this correlation indicates that the results maintain a satisfactory level of accuracy, as demonstrated by the Root Mean Square Error (RMSE) values, which are 2.86 for water content, 5.4 for liquid limit, and 3.85 for plastic limit, 2.9 for optimum moisture, and 13.86 for maximum dry density. By integrating satellite-derived MNDWI water indexes with soil parameters, a fast, accurate, and cost-effective method for estimating soil parameters and modeling their spatial distribution in the study area can be developed. Additionally, the findings suggest that the IDW method, implemented using spatial analyst tools, performed exceptionally well for mapping the study area. In conclusion, the results of this research can be utilized by land use planners, municipalities, policymakers, and engineers to develop practical and effective plans.

High-frequency two-stage gas-bearing pulse tube cryocoolers at 20 K for space applications

Gas-bearing pulse tube cryocoolers (PTCs) are efficient and durable for the elimination of supporting and reciprocating parts of the compressor components. Compared with the leaf-spring-suspension compressors, the PTCs with the characteristics of high efficiency, lightweight, compactness, and considerable temperature regulation of PTCs have arousedwideconcern but were rarely investigated. Here, we report the regenerative packing sections of two-stage PTCs under harsh working conditions (i.e., the hot-end temperatures of the compressor and cold finger were 333 K and 313 K, respectively), and the dimensions of pulse tubes (1st and 2nd) were systematically explored. The heat functional (sub)structures and obtained compressor curves coupling with the cold fingers showed an excellent cooling capacity of 0.05 W@20 K at the heat rejection temperature of 293 K. The operating frequency is 52 Hz, which is far beyond the typical high-frequency 40 Hz; and the input electric power is 450 W. Gas-bearing PTCs can meet the requirements of space telescopes for 20 K temperature regions. This study makes a difference in promoting the application of gas-bearing PTCs in cryogenic cooling and remote sensing for aerospace applications, which also provides a feasible way to realize the lightweight of space cryocoolers with considerable efficiency, high reliability, and durable lifespan.

Effect of mineral fillers on epoxy-modified open-graded porous asphalt durability

ABSTRACT Epoxy-asphalt (EA) attracted the attention of road authorities in many countries as a solution for open-graded porous surface layers with enhanced durability and longevity. This research presents an experimental programme to assess the durability of epoxy-modified open-graded porous asphalt (EMOGPA) mixes, emphasising the effects of the reactivity of two mineral fillers on mixes containing various EA proportions. Results indicate that the EMOGPA mixes have shown a high sensitivity to the conditioning time before compaction (aka. preconditioning). The materials produced exclusively by EA are the most sensitive to preconditioning, reducing their water and ravelling resistance with increased preconditioning time lengths. The number of gyrations has also been proven as an efficient quantity of the compaction effort required to reach the target mix properties. Moreover, the proportional increase of EA in mixes led to substantially improved durability. Hydrated lime in epoxy-modified asphalt mixes also affected their mechanical response. The indirect tensile strength and toughness of EA mixes were higher than other mixes, while mixes with limestones were stronger and tougher than those with hydrated lime. This attribute reflects the positive contribution of apolar fillers to strengthen and toughen the EA mixes.

Mesoscopic Analysis of the Compaction Characteristics of Rockfill Materials Considering Gradation and Shape

Mesoscopic Analysis of the Compaction Characteristics of Rockfill Materials Considering Gradation and Shape