2031 research outputs found
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Shearing Behavior at the Interface of Sand-Structured Surfaces Subjected to Monotonic Axial Loading
Get PDFEnhancing the interface shear strength is crucial in the capacity and design of several geotechnical structures when subjected to static loading. The efficiency of these structures can be enhanced by utilizing innovative designs that allow the mobilization of higher interface shear resistance with bio-inspired-engineered or structured (rough) surfaces when compared to conventional smooth or random rough surfaces of the same geometry (i.e., soil-foundation contact area). Bio-inspired-engineered surfaces used in this study are developed after surfaces with snakeskin-inspired and engineered rough designs that maximize the interface shear resistance in cohesionless and cohesive soils. The frictional behavior and resistance of the bio-inspired-engineered surfaces were experimentally evaluated utilizing a modified interface direct shear apparatus on three locally available sand specimens. Results from tests on smooth surfaces against three different sands mobilized almost the same resistance and soil contraction. The results indicate a behavior significantly influenced by the shape and arrangement of the surface features, accompanied by larger resistance and volume dilation. A parametric study on the characteristics of the structured elements on three sands revealed the isolated impact of elements arrangement, shape, and roughness on the maximum attainable interface strength. The surface element characteristic ratio is found to control the load-transfer mechanism between sand and bio-inspired-engineered structured surfaces. Doi: 10.28991/CEJ-2024-010-10-06 Full Text: PD
Role of Slag Replacement on Strength Enhancement of One-Part High-Calcium Fly Ash Geopolymer
Get PDFThis paper reports the effect of slag (SL) replacement and water-to-binder (w/b) ratio on properties of one-part geopolymer derived from high-calcium fly ash (FA) and sodium silicate powder (NP). The FA was replaced by SL at the rates of 20% and 40%, respectively. This study focused on conducting experimental tests to evaluate the relative slump, setting time, compressive strength, and flexural strength of one-part FA-based geopolymer. The relationship between compressive and flexural strengths of one-part geopolymer mortar was expressed using the simplified linear regression model, whereas the normalization of compressive and flexural strengths with SL replacement by the strength of one-part geopolymer mortar without SL as the divisor was also evaluated. Experimental results showed that the increase of SL replacement and w/b ratio significantly affected the workability and strength development of one-part geopolymer mortar. Higher SL replacement exhibited a positive effect on their compressive and flexural strengths; however, a reduction in its setting time was obtained. The enhancement in strength development of one-part geopolymer was primarily due to the increased calcium content of SL. Similarly, reducing the w/b ratio in the production of one-part geopolymer resulted in a decrease in setting time and an increase in strength development. Based on the relationship between compressive and flexural strengths, the prediction coefficient value (R2) obtained from the curve fitting procedure was 0.835, indicating a good level of reliability and acceptability for engineering applications. Doi: 10.28991/CEJ-SP2024-010-013 Full Text: PD
Analysis of Tetrachiral Sandwich Structures at High-Velocity Impact: Influence of the Applied Material and Projectile Core Geometry
Get PDFThis research involved ballistic impact analysis on a tetrachiral sandwich structure in which the shapes of the circular nodes in the tetrachiral core are modified into polygonal shapes, namely a square, hexagon, and octagon. The objectives of this study were to observe the effect of a modified sandwich tetrachiral structure core, investigate the effect of the projectile geometry, and calculate the material performance of the structure. This research was conducted using numerical analysis utilizing the finite element method. The simulation methodology was validated through a benchmarking study, the results of which showed an error below 6%. The findings show that the material with the best performance was Armox 500T, at 5033 J. The most difficult projectile to withstand was conical, followed by ogive, hemispherical, and blunt. The results of the core modification on the tetrachiral sandwich structure show that the octagonal core had better energy absorption, by 2.8%, compared to the circular core. Modifying the node geometry in the tetrachiral core and then analyzing it with stress and strain contours are the novel aspects of this research. Doi: 10.28991/CEJ-2024-010-10-017 Full Text: PD
Experimental Study of the Principal Characteristics of Sustainable Micropile Grout Containing Alternative Sands
Get PDFThe paper discloses a laboratory investigation on employing manufactured sand cement as grout in micropiling works. In practice, to prepare micropile grouts, Portland cement is commonly used. The grout usually consists of natural sand to obtain the strength parameters and value international standards require for micropile construction. It is common knowledge that using concrete and natural sand leaves its environmental footprint. Although there have been numerous attempts to use more environmentally friendly materials, utilizing manufactured sands, particularly for micropile grouting, is a scientific challenge that researchers are still trying to address. The present study investigates the performance of micropile grout mixtures containing manufactured (M) sands, including limestone (L-M) and granite (G-M) rock as replacements for natural sand. For this purpose, laboratory tests, including unconfined compression strength (UCS) and workability tests, were conducted on samples with varying compositions and ratios of L-M and G-M materials. The complementary microstructure and chemical composition analyses were performed using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analysis. The laboratory results indicate that the UCS at 28 days of hardening for all M-sand cement mixtures exceeds the minimum standards required values, falling in a range of 40-50.2 MPa. It's noteworthy that the strength of cement grout containing L-M sand was found to be higher than that of G-M sand. The SEM results show the G-M sand grain is rougher than L-M, and the L-M sand grain size is finer than the G-M samples, which causes a decrease in porosity at the interfacial transition zone. Grout workability tests demonstrated that higher water-cement ratios (W/C) led to increased fluidity across all mixtures, with G-M sand resulting in lower flowability than L-M samples. Overall, the results suggest that the proposed mixtures could serve as sustainable alternatives for micropiling, reducing cement content and utilizing alternative, reused materials in grouting mixtures more effectively and sustainably. Doi: 10.28991/CEJ-2024-010-10-019 Full Text: PD
Experimental Study on the Effect of Flow Velocity and Slope on Stream Bank Stability (Part II)
Get PDFErosion significantly contributes to the instability of riverbanks. The current study considers the issues of instability and erosion that plague the banks of the Al-Muwahada channel. It was a large irrigation channel located west of Baghdad, Iraq. A laboratory flume was constructed to gain a comprehensive understanding of the erosion process on riverbanks. This flume serves as a scaled-down replica of the Almowahada channel. The main structure of the flume consists of a 3-meter steel construction with dimensions of 1 meter in width and 0.6 meters in height. In order to reduce the high flow velocity, it was periodically linked to quieting tanks with dimensions of 1 meter in width, 1.5 meters in height, and 0.4 meters in thickness. The flume's sidewalls are constructed with plexiglass that is 4 mm in thickness. Furthermore, a water reservoir with a capacity of 1800 liters was introduced into the flume. A riverbank was constructed with two slope angles, one at 45º and the other at 60º. The bank was then subjected to five different velocities. The experimental results indicate the velocity of flow and slope angle of the riverbank are the primary factors that influence the stability of the riverbank. The tipping point between erosion and deposition rises increasingly as the flow velocity increases. The majority of the sediment at the bottom, particularly on the near side of the bank, is the result of bank erosion. As the slope angle of the riverbank approaches 37°, it becomes more stable. The erosion-induced deformation in the riverbank with a slope angle of 45º is greater than that in the riverbank with a slope angle of 60º. The investigation demonstrated that the 45° angle is more susceptible to erosion caused by the flow velocity than the 60° angle. Doi: 10.28991/CEJ-2024-010-10-012 Full Text: PD
Influence of Integral Crystalline Waterproofing on Concrete Properties: Dosage Impact and Microstructural Analysis
Get PDFThe present research study aims to investigate the properties and performance of concrete containing an integral crystalline waterproofing (ICW) admixture, added at an optimal dosage to resist water without compromising structural integrity. To achieve this, an experimental program was conducted on specimens with ICW dosage variations ranging from 0 to 4.8 kg/m2. The impact on water absorption, pulse velocity, and microstructural characteristics was tested and analyzed using XRF and EDS techniques. The findings reveal that increasing the dosage decreases water absorption by approximately 43% at maximum dosage compared with the control. A 41% increase in pulse velocity indicates a denser concrete matrix. The principle of optimization is highlighted, as an overdose of ICW generates a non-structural crystalline gel at the bottom of the specimens. The optimum dosage range for ICW to improve water resistance without adverse effects on structural performance was determined to be 3.2 to 4.0 kg/m2. This research introduces a novel approach by evaluating the comprehensive performance of concrete in relation to ICW dosage, providing valuable insights into the practical application of ICW admixture to enhance concrete quality and durability. Doi: 10.28991/CEJ-2024-010-10-02 Full Text: PD
Analysis of Climate Change Scenarios Using the LARS-WG 8 Model Based on Precipitation and Temperature Trends
Get PDFGlobal food production and water distribution are at risk due to increasing temperatures and changing precipitation trends. The main objective of the study was to analyze the climate trend and future projections in seven stations in southern Iraq. The period (1981–2020) was designated as a base period. The periods (2021-2040) and (2041-2060) were defined as the future two periods. The Mann-Kendall trend test was employed to assess trends utilizing XLSTAT. The study employed the most recent version of the LARS-WG 8 model to forecast climate change by using three GCMs (ACCES-ESM1-5, HadGEM3-GC31-LL, and MRI-ESM2-0). These simulations are based on two scenarios (SSP-245 and SSP-585). The statistical indicators provided support for the outcomes of model calibration and validation, demonstrating its competence and reliability. The results of this analysis indicate that there is a non-significant increase in precipitation and a considerable increase in both maximum and minimum temperatures during the period (1981-2060). The downscaled result reveals an increase in monsoon precipitation in the range of 2.233-2.831 mm under SSP-245 and SSP-585, respectively, compared with the base periods 1981-2020 during the Near Future and 1.988-2.543 mm during the mid-future. Also, annual maximum/minimum temperature increases in the range of (1.156-1.549 °C) and (1.486-1.770 °C) during the Near Future. (2.095-2.892 °C) and (1.486-1.770 °C) during the mid-future, respectively, for SSP-245 and SSP-585. These outcomes can enhance understanding to develop strategies for mitigating and adapting to these impacts. Doi: 10.28991/CEJ-2024-010-12-014 Full Text: PD
Novel Ni/ZnO Nanocomposites for the Effective Photocatalytic Degradation of Malachite Green Dye
Get PDFWater scarcity threatens human civilization because of rapid industrialization's damage to freshwater sources. Pollutants like dyes, which are frequently found in the paper, leather, food, plastics, textile, and cosmetics industries, must be removed to preserve water. In the present study, Zinc oxide nanocomposites impregnated with nickel (Ni/ZnO) were prepared using a wet impregnation technique. These novel materials were investigated for their ability to photocatalytically degrade malachite green (MG) under the irradiation of visible. The synthesized nanocomposite catalyst was characterized by various analytical techniques, including SEM, EDX, XRD, and BET methods of surface analysis, and revealed a high surface area of 192.88 m2g-1 with an average size range from 88-354 nm. EDX results showed efficient doping of Ni (28.9%). The composites were then used under the influence of a visible light source to degrade MG dye. The investigation also assessed the degradation of MG using a photo-Fenton reagent. Factors such as catalyst dosage, H2O2 levels, pH, and duration were optimized to understand their impact in both degradation studies. The synthesized catalyst showed stunning photocatalytic activities, as 99.4% of the 60 µg.ml-1of MG was degraded in 40 min with 100 mg of Ni/ZnO at pH 8. Ni/ZnO had a good application prospect for MG degrading and can be used as a potential photocatalyst. Doi: 10.28991/CEJ-2024-010-08-011 Full Text: PD
Utilization of Sand Cushion for Stabilization of Peat Layer Considering Dynamic Response of Compaction
Get PDFSoft peat soils are located in many zones and at a given depth all over the world and are characterized by their low shear strength and high settlement. It can also cause progressive failure of roads, embankments, and foundations. Sand cushioning is the most beneficial technique used to relieve the stress transmitted to the peat layer to mitigate any deformation and shear failure. In this research, a field study of a road with a soft peat layer located at a depth 4m below the ground surface is carried out. The plate load test is conducted on three cases over the peat layer using sand cushions with and without reinforcement. The results were compared with plate footing on the surface of the road without stabilization. The field tests of the improved technique were verified and deeply analyzed using the numerical program Plaxis. The finite element analysis mainly sheds light on the simulation of the dynamic response that represents the compaction of the sand cushion over the peat layer. A series of numerical models has been done considering the effect of repeated load compaction on the adopted sand cushions with and without reinforcement. The numerical analysis is directed to show the effect of repeated loads of compaction equipment that were used on decreasing the stress over the peat layer. The results showed that the composite compacted cushion with both a higher number of cycles and stress has a great effect on relieving the stresses transmitted to the face of the peat. As a result, the footing capacity is increased with less deformation. Doi: 10.28991/CEJ-2024-010-04-011 Full Text: PD
Asphalt Mix Compressive Stress-Strain Behavior: An Analytical and Experimental Study of Variable Influence
Get PDFTo address the excessive depletion of natural resources in Indonesia's civil construction sector, there's a rising trend in utilizing plastic waste from packaging, such as beverage bottles and plastic bags, alongside renewable energy sources like Modified Buton Asphalt (MBA). MBA serves as a partial substitute for both fine and coarse natural aggregates and non-renewable energy sources like petroleum bitumen. This study aimed to investigate the effects of incorporating polyethylene terephthalate (PET) and polypropylene (PP) waste as partial substitutes for coarse and fine aggregates through experiments and t-tests. The objective was to determine how the stress-strain behavior of asphalt mixtures formed using MBA changed with the addition of this mixture. Additionally, compressive strength and elastic modulus were calculated under mixed compressive loads. PET and PP plastic waste replaced natural coarse and fine aggregates at three volume percentages: 1%, 2%, and 3%, with a PET:PP ratio of 50%. A manual grater was used to shred PET and PP plastic bottles into shredded plastic waste, which was retained in sieve no. 50 after sieving. The study found that adding PET, PP plastic, and MBA waste enhanced the asphalt mixture's mechanical strength and modified relevant variables, resulting in a more elastic and ductile behavior. Doi: 10.28991/CEJ-2024-010-05-011 Full Text: PD