Cylindrical Specimens Research Articles

The investigation of wear properties of nanoparticle-reinforced epoxy composite material surfaces

This study added nano-sized Al2O3, Boron, and TiO2 powders to the epoxy polymer at 0.5% and 1% ratios. Abrasive wear resistance properties of nanoparticle-reinforced epoxy polymers were investigated. First cylindrical specimens with and without additives were prepared for realizing the experimental research. Pin-on discs were used for the wear test of epoxy samples. The mass losses were measured via a precision scale. According to the results, the boron nanoparticles have increased the epoxy specimens’ resistance. As a result of the experimental studies, it was observed that the wear resistance of the epoxy composite increased with each nano-sized powder added to the epoxy. SEM and optical profilometry investigated the composites’ friction coefficient and surface morphology. As a result of friction coefficient and wear weight loss tests, the highest wear resistance was obtained in 1% boron powder nano-reinforced epoxy composites. It was observed that the epoxy friction coefficient was in the range of 0.4–0.6, which decreased to the range of 0.2–0.4 with the addition of nano boron. The surface roughness value after epoxy wear was measured as 1.4 μm. With the addition of nano boron, this value was measured as 0.32 μm. Optical profilometry and SEM imaging results also support these values.

A Study on the Abrasion Resistance of Hydraulic Structures with Different Repair Mortars

One of the main problems with hydraulic structures is that floating silt, gravel, ice sand, boulders, and other materials circulating over a concrete surface have an abrasive effect that causes hydraulic structures to abrade. Abrasion causes concrete to degrade, which could eventually expose the reinforcing to corrosion. In addition to section loss, reinforced concrete hydraulic structures’ endurance may also be a problem. Repair mortars are used to restore surfaces that have been abraded. The suitability of various repair materials for use as a repair layer on concrete surfaces is examined in this study. In order to apply different repair mortars to concrete specimens and subject them to abrasive forces, this work employs an experimental methodology. The ASTM C 1138 standard was followed for testing the abrasion resistance of the samples repaired using repair mortars underwater. Both silica fume mortar and polymer-modified mortar were employed in the study as forms of repair mortar. For each type of repair mortar, three cylindrical concrete specimens were cast, along with control specimens. Hence, nine cylindrical concrete samples in total were employed in this study. In order to quantify the effect of abrasion and, consequently, to assess the efficacy of various repair materials, abrasion volume loss was measured. Important findings about each type of repair material’s resistance to underwater abrasion are included in the study. The findings show that in terms of abrasion resistance underwater, the polymer-modified mortar performs better than the silica fume mortar.

Experimental investigation of the performance of normal and high-strength concrete confined by UHPFRC jacketing

This paper performed compressive tests on 24 cylindrical specimens strengthened by an ultra-high performance fiber-reinforced concrete (UHPFRC) jacket. In order to investigate the influence of the concrete strength on the confinement effectiveness, the tests were made with 3 different concrete grades, C25, C40, and C60, using jackets with 25 mm and 35 mm thickness. The results showed that the UHPFRC jacket might significantly increase the confined concrete strength for the 3 different concrete classes. The circumferential strain analysis showed that the relation between the concrete strength and the jacket thickness impacts the jacket's effectiveness. This influence seems essential in comprehending the UHPFRC jacket with undersized or oversized dimensions. Some concrete confinement models were tested to predict the confined concrete strength. A suggestion of an equation to predict the concrete strength was proposed based on the influence of the behavior of the oversized and undersized UHPFRC jacket thickness.

Measurement of three-dimensional shrinkage deformations and volumes of stabilised soft clay during drying with Structure from Motion photogrammetry

The paper applies the Structure from Motion photogrammetry technique to measure three-dimensional shrinkage deformations of a cylindrical specimen during drying. A clay–binder mixture was statically compacted, and its shrinkage behaviour was observed for four weeks with a newly established photogrammetric system. The complete surface information including XYZ coordinates and RGB values was then reconstructed and formed into dense point cloud data, with which the volume change and shrinkage deformations are computed. In volume change determination, the reconstructed dense point cloud achieves a fine reproduction of the specimen surface, leading to satisfactory accuracy. The computed volume deviation was within 495.3 mm3 (0.24%) and 4170 mm3 (1.83%) for the dummy cylinder and clay specimen, respectively. Both values are significantly smaller than the volume deviations computed with a classical approach that involves artificially creating markers on the specimen surface. In the computation of shrinkage deformations, the paper proposes a novel method that detects the fast point feature histogram of the point clouds and then matches the detected descriptors, leading to an improvement in three-dimensional deformation determination. The compacted sample shrinks, and the computed axial deformations increase quasi-linearly with height. However, due to the noticeable tilt that occurred during drying, the calculated radial deformations are scattered at the same height and appear misleading. Circumferential deformations and strains are therefore adopted to represent the true material behaviour.

An approach of repairing concrete vertical cracks using microbially induced carbonate precipitation driven by ion diffusion

Microbially induced carbonate precipitation (MICP) is an eco-friendly method of repairing cracks in concrete. However, for vertical cracks appeared in concrete components, the microbial mineralization solution injected into cracks tends to flow out due to gravity, resulting in incomplete crack repair. To address this obstacle, this study presents a novel approach in repairing vertical cracks using MICP with the ingression of calcium and urea driven by ion diffusion. For this purpose, a combined injection and diffusion method (CIDM) is proposed, in which the bacterial solution (ureolytic bacterium Sporosarcina Pasteurii) was first injected into crack and then the crack surface was adhered with a sponge containing the saturated cementation solution (urea and calcium acetate) for continuous ion diffusion. In comparison, the traditional injection method (TIM) is also conducted on the test cylindrical specimens. In addition to the pre-cracked concrete cylinders, four transversely load-induced cracked concrete beams were also utilized in this study and their vertical cracks were treated with CIDM under both loading and unloading conditions. The crack repair effects are evaluated by means of surface observations, microanalysis, water absorption tests and chloride penetration tests. Test results indicate that the proposed CIDM, whereby the calcium and urea are supplied through an ion diffusion approach, is a more effective method to repair vertical cracks than TIM. The generated white precipitations in cracks are confirmed to be calcium carbonate crystals existed in form of vaterite through energy dispersive spectrum (EDS) and X-ray diffraction (XRD) examinations, which also indicate that the CIDM method tends to produce a denser calcium carbonate cluster structure. After crack repairing with CIDM, the improvement coefficients of waterproof performance for the pre-cracked cylinders with widths of 0.1, 0.2 and 0.4 mm are 84.2%, 81.2% and 73.6%, respectively, which is 6%–12% higher than those got from TIM method. Furthermore, the average improvement coefficients of resistance to chloride penetration for vertical cracks with widths from 0.085 mm to 0.162 mm are about 76.9% and 88.5% for the sustain-loaded beams and unloaded beams, respectively.

Study on the Utilization of Waste Thermoset Glass Fiber-Reinforced Polymer in Normal Strength Concrete and Controlled Low Strength Material.

Thermoset glass fiber-reinforced polymers (GFRP) have been widely used in manufacturing and construction for nearly half a century, but the large amount of waste produced by this material is difficult to dispose of. In an effort to address this issue, this research investigates the reuse of thermoset GFRP waste in normal strength concrete (NSC) and controlled low-strength materials (CLSM). The mechanical performance and workability of the resulting concrete were also evaluated. To prepare the concrete specimens, the thermoset GFRP waste was first pulverized into granular pieces, which were then mixed with cement, fly ash, and water to form cylindrical concrete specimens. The results showed that when the proportion of thermoset GFRP waste aggregate in the concrete increased, the compressive strengths of NSC and CLSM would decrease. However, when incorporating 5% GFRP waste into CLSM, the compressive strength was 7% higher than concrete without GFRP. However, the workability of CLSM could be improved to meet engineering standards by adding an appropriate amount of superplasticizer. This finding suggests that the use of various combinations of proportions in the mixture during production could allow for the production of CLSM with different compressive strength needs. In addition, the use of recycled thermoset GFRP waste as a new aggregate replacement for traditional aggregates in CLSM was found to be a more sustainable alternative to the current CLSM combinations used in the market.

Bauxite residue as a binary additive in lime treated soil composites

Industrial solid wastes have been valorized as binary and ternary admixtures in earth modification and treatment of problematic soft soils. In this investigation, an industrial waste from the aluminium industry, viz. Bauxite Residue was assessed to understand its efficacy as a binary addendum to lime in improving swelling soils. The novelty of this investigation is its focus on the combination of a scientifically established lime content viz. optimum lime content and low doses of Bauxite Residue, which seems to be virtually absent in published literature. The investigational trial explored the unconfined compression strength and stress–strain characteristics of the lime treated soil composites, treated using combinations of 7% lime and 0.25%, 0.5%, 1% and 2 % bauxite residue. The lime treated soil composites were moulded in to cylindrical specimens of 38 mm diameter and height of 76 mm, cured in air-tight polyethene covers for two hours, three, seven, fourteen and twenty-eight days and tested for their unconfined compression strength. The outcome of the investigation was also compared with some previous investigations from available literature. It was revealed that 2% bauxite residue blended lime treated soil composites was the most ideal out of all combinations studied for developing maximum strength of the lime treated soil composites. It was also noticed that bauxite residue blending of the lime treated soil composites did not affect the strength progression trends irrespective of the bauxite residue content and post peak stress–strain behaviour of the lime treated soil composites improved with increasing bauxite residue content.

Mechanical Properties of Deep Variable Dip Joint Rock Mass in Reservoir Area under Wet and Dry Conditions

The mechanical property of deep complex jointed rock mass is a hot topic in rock mechanics. In order to grasp the deformation and damage rules of through-going variable dip joint rock masses, the triaxial compression test and joint surface morphology scan test were conducted on cylindrical specimens in dry and wet conditions under 0, 5, 10, and 20 MPa water pressure. Through these tests, the deterioration law of rock samples under different pore water pressure in dry and wet conditions was studied. The effect of pore water pressure on the strength of saturated jointed rock sample is nonlinear. The imposed pore water pressure can significantly increase the axial deformation of rock samples, and higher pore water pressure can facilitate the deformation deterioration of samples. When the pore pressure is high, the rock samples show the characteristics of sliding shear failure. Under different pore pressure, the compressive strength of dry jointed rock is significantly higher than that of saturated jointed rock, and the saturated rock is more susceptible to sliding in the joint plane than dry rock. Dry jointed rock samples have stronger deformation ability than saturated jointed rock samples. The change rate of the morphologic parameters and the distribution of the failure cracks indicate that the stress concentration is evident in the middle of the joint plane.

Effects of process parameters and loading direction on the impact strength of additively manufactured 18%Ni-M350 maraging steel under dynamic impact loading

The microstructural and damage evolution of 18%Ni M350 maraging steel fabricated by laser-based directed energy deposition (DED) process under dynamic impact loading are investigated in this study. The influence of additive manufacturing (AM) processing parameters, including laser power, powder feed rate, and energy area density (EAD) are discussed. The mechanical testing of the additively manufactured alloy was done using the split Hopkinson pressure bar (SHPB) system. The dynamic impact test was conducted using strain rates ranging from 100 to 4000 s−1. The test was conducted on cylindrical specimens (7 mm diameter and 8 mm long) with axes parallel to the build direction (Z-axis) and perpendicular (X- and Y-axis) to the build direction to evaluate the effects of loading directions on mechanical responses and microstructural evolution in the alloy under the impact loading conditions. The test results revealed that the materials processed using the lowest EAD parameters exhibit the greatest impact strength under dynamic impact loading for all directions. Specimens impacted along the build direction (Z-axis) exhibit a continuous drop in peak flow stress once the strain rates exceeded 2300 s−1 indicating the greatest susceptibility to thermal softening at high strain rates. Strain localization leading to the formation of adiabatic shear bands (ASB) was observed in some specimens. Cracks developed along the ASBs, while some AM-process-related defects, such as the lack-of-fusion, interacted with adiabatic shear bands, promoting cracking inside the shear bands. Despite possessing the highest impact strength, the materials produced by the lowest EAD parameters are the most susceptible to the development of adiabatic shear bands leading to cracking and fracture.

Contact fatigue studies on L-PBF processed IN718 alloy tested under no slip condition

This paper investigates the influence of heat treatment on rolling contact fatigue (RCF) performances of Laser Powder Bed Fusion (L-PBF) processed IN718 alloy. The cylindrical specimens (Ø9.5 mm) produced with optimised parameters are subjected to RCF testing under boundary lubrication conditions. RCF results show that improved performance about 40% after heat treatment is due to the restoration of strengthening precipitates. The improved bulk hardness by 27% resulted in RCF life enhancement by 2.5 folds. From sub-surface analysis, it was found that the L-PBF produced specimens seen to be more prone to trans/inter-track and interlayer crackings than conventional wrought IN718 alloy, which predominantly showed intergranular and transgranular cracks.

Green electrochemical polishing of EBM Ti6Al4V samples with preliminary fatigue results

Additive manufacturing technologies have several well-known advantages; however, the surface quality of the printed parts is poor, compromising the corrosion and mechanical properties. Thus, surface finishing treatments are necessary. The most post-processing treatments proposed in the literature are mechanical or chemical. The formers are contact techniques and cannot be suitable for complex geometry, while the latter use strong and dangerous reagents. This paper is aimed to investigate the effect of the electropolishing treatment, a contactless technique, using an eco-friendly electrolytic solution in reducing the roughness and improving the fatigue properties of Ti6Al4V specimens produced by electron beam melting technology. Several parameters affecting the effectiveness of the electropolishing treatment have been investigated, as interelectrode distance, stirring rate and duration time. An optimal combination of them allowed a uniform surface treatment and a significant roughness reduction (64% of Sa reduction for cylindrical specimens). Under sinusoidal loading conditions with a maximum stress of 378 MPa and a stress ratio equal to R = 0.1, the mean fatigue life of electropolished dog-bone specimens was 250% longer than that of as-built specimens.

Stiffness of cold-recycled mixtures under variable deformation conditions in the IT-CY test

Stiffness modulus belongs to the most important properties describing the cold-recycled mixtures (CRM) in terms of their usability in road pavement structures. Previous research proved that this property is strongly dependent on the scheme and conditions of the test (temperature and time of loading) and the time that has passed since the compaction of the specimen or pavement layer. It is a result of the influence of two different types of bonds – hydraulic bonds from cement and bituminous bonds from bituminous emulsion or foamed bitumen. Research presented in this paper showed that the target horizontal deformation values selected during the stiffness modulus test have a strong impact on the obtained results as well. In this paper the popular Indirect Tensile Stiffness Modulus (ITSM) test on cylindrical specimen (IT-CY scheme) was used to show the dependence of the stiffness modulus values on the selected target horizontal deformation level. Research was conducted on four different CRM mixtures and three reference materials. The research proved that even for a narrow deformation range the CRMs do not present linear viscoelastic behavior and display very high effort of material even for typical test conditions. In consequence, they are very prone to failure. Research also proved that CRM mixtures present different rheological behavior than cement concrete or asphalt concrete, and more attention should be given to establishing proper test conditions. Based on the research, it was determined that the recommended target horizontal deformation in IT-CY test of CRM should be reduced to 3 µm.

Sustainable Materials from Waste Paper: Thermal and Acoustical Characterization

A growing research interest currently exists in the use of paper as a building material. This work aims to present the results of a measurement campaign developed on innovative waste paper-based building components. The research was carried out in Southern Italy and used some local by-product aggregates. Three different mixture designs were developed in the laboratory by adding three kinds of biomass to a pulp paper blend: fava bean residues (FB), sawdust powder (SP) and coffee grains (CG) extracted from exhausted chaffs. A physical characterization was carried out measuring the bulk density and bulk porosity. Scanning Electron Microscopy (SEM) analysis of the single aggregates was followed by a microstructure analysis of the final components. Bulk density evaluation showed a range between 200 and 348 kg·m−3. Furthermore, thermal performances were measured; the thermal conductivity of the experimented samples ranged from 0.071 to 0.093 W·m−1·K−1, thus it is possible to classify the tested materials as thermal insulators. Moreover, the acoustic properties were evaluated and tested. The normal incidence sound absorption coefficient was measured by the impedance tube on cylindrical specimens. In general, a different behavior was observed between the upper and lower base of each specimen due to the manufacturing process and the shrinkage caused by the different interactions occurring between the aggregates and the pulp paper waste; for example, the presence of sawdust reduced shrinkage in the final specimens, with consequent smaller physical variations among the two faces. The correlation existing between the manufacturing process and the microstructural properties was also investigated by the estimation of the non-acoustical parameters using the inverse method and taking into account the JCA (Johnson, Champoux and Allard) model as a reference.

Evaluation of gypsum waste for 3D decorative plate production

The concern with the amount of plasterboard waste produced during the process of construction and/or renovation, generates interest in studies that evaluate the reuse of this waste, avoiding the inappropriate disposal. In this way the present work has as its main objective to evaluate the use of gypsum waste in the production of 3D decorative plates. The gypsum was recycled through processes of cleaning, crushing, sieving and calcination at different temperatures. Cylindrical specimens and 3D decorative plates were developed with recycled gypsum without calcination and calcined recycled gypsum at temperatures of 150 ºC, 180 ºC and 200 ºC. These specimens were tested for compressive strength (cylindrical specimens) and flexural strength (3D decorative plates) 7 days after modeling. The results showed that there was no difference in compressive strength between recycled gypsum without calcination, recycled gypsum with calcination and natural gypsum. As for the flexural tensile strength, it was observed that the recycled gypsum without calcination had an average value 15% lower than the reference specimens.

Laboratory Wheel Tracking of Asphalt with Rubber Tires or Rubber Hoses

In recent years, wheel tracking of asphalt mixtures has gained considerable momentum, and the authors are evaluating the potential of standardizing a rubber-tire wheel tracking protocol which can enable direct decoupling of rutting and moisture damage by testing identical specimens in dry and wet conditions. Previous work has established the value of dry and wet comparisons; this paper specifically assesses the dry rutting component by comparing a rubber-tire wheel tracker known as the PURWheel-G2 with the asphalt pavement analyzer (APA), arguably the most well-known dry wheel tracking test. This paper has two main objectives: demonstrate that rubber-tire wheel tracking is capable of characterizing dry rutting in a manner comparable to the APA and recommend initial failure criteria for rubber-tire wheel tracking. The PURWheel-G2 was more variable than the APA with coefficients of variation nearly twice as large. Although there was variability, reasonable rut depth correlations were drawn between the PURWheel-G2 and APA, and an APA pass/fail criteria of 6 mm equated to 10 mm for conventional PURWheel-G2 testing using laboratory-compacted slabs. Using literature and available data, 6 mm was proposed as a rubber-tire pass/fail threshold when standardizing to typical APA compaction methods and boundary conditions (i.e., cylindrical specimens in confined molds). Ultimately, efforts are ongoing to improve limitations of the PURWheel-G2 prototype (e.g., variability) with modernized equipment, and the authors recommend agencies initially consider the same failure criteria already established for APA testing and be willing to adjust over time as data and experience dictate the need to do so.

An investigation on ultrasonic wave velocity of laminated sandstone under freeze-thaw and salt crystallization cycles: Insights from anisotropy effects

In this study, the anisotropy effects on the P (Vp) and S (Vs) wave velocities are investigated in laminated sandstone subjected to freeze-thaw (FT) and salt crystallization (SC) processes. For this purpose, cylindrical core specimens were prepared from sandstone at angles (β) of 0°, 30°, 45°, 60°, and 90° to the lamination direction. Next, FT and SC tests were performed up to 60 cycles. After every 10 cycles, the specimens’ Vp and Vs were determined at various β values. The decay constant (λ), half-life (N1/2), and rate of loss (RL) were used to investigate the anisotropy effects on the Vp and Vs of specimens under FT and SC and compare the effects of FT and SC on the Vp and Vs. The results indicated that anisotropy is an important factor in the durability of the specimens against FT and SC. In this respect, the specimens with β = 0° and β = 60° had the least and the highest changes in the Vp and Vs, respectively. Also, it was found that the anisotropic behavior of the specimens is different at various cycles of FT and SC such that it is intensified at higher cycles. Overall, it was concluded that SC had more significant effects on the Vp and Vs compared to FT. Considering the β values, the effect of a single cycle of the SC test in decreasing the Vp and Vs of the specimens corresponds to 1.34 to 1.94 and 1.28 to 1.70 cycles of the FT test, respectively.

Laminated Jute and Glass FibreReinforced Composite forRepairing Concrete Through Wrapping Technique

Natural fiberreinforced composite in concrete structure material has attracted many researchers and engineers in recent decades due to its good agreement in mechanical properties, economics, and sustainability. An experimental investigation was conducted to investigate the jute and glass fiberlaminated composite for cylindricalconcrete repair.Jute and glass fiberwere used as reinforcement, and vinyl ester (VE) served as the matrix.The vacuum bagging technique was used to wrap the cylindrical concrete columns with a diameter of 50 mm and a height of 150 mm.Compression and Brazilian tests were performed on the specimen.It was discovered that the four (4) layers of jute fiberreinforced thermoset (JFRT) composite had the highest mechanical properties, with an improvement of 72.62%when compared to glass fibrereinforced thermoset (GFRT) composite. It can be concluded that both GFRT and JFRT had the potential to improve the mechanical properties performance of cylindrical concrete specimens with an increase of up to five (5) layers of woven fiber.The results presented here may facilitate improvements in the concrete specimen by using JFRT where it was suggested to have a higher improvement for the concrete specimen with the optimum layers applied.As a result, jute fiberhas been shown to perform better and can be used as an alternative to glass fiber.As a result, jute fiberhas been shown to perform better and can be used as an alternative to glass fiber.

Vinyl-ester-based polymer concrete incorporating high volume fly ash under tensile, compressive, and flexural loads

The utilization of innovative, lightweight, durable, and ecologically friendly polymer concrete is becoming more popular. Therefore, this research was conducted to investigate the mechanical performance of polymer concrete produced using Vinyl Ester (VE) resin and high-volume Fly Ash (FA) filler with a focus on compressive, tensile, and flexural strength of strong and weak axes using a three-point flexural test. It is important to note that the resin varied from 20 to 90%, FA from 10 to 20%, Mepoxe (MK) catalyst was 4.5%, and Cobalt (Co) was 1% of resin volume. Moreover, cube specimens were used to determine compressive strength and specific gravity at 3 days, cylindrical specimens were also used to determine compressive strength at the age of 1 and 2 days, and dog-bone-shaped specimens were used for tensile strength. This research also applied a three-point flexural test to both the strong and weak axes of the specimens. The result showed that the specimen with 30% VE and 70% FA (RUN-3) had the most effective compressive strength, specific gravity, price, and casting simplicity or workability as by the 66,2 MPa recorded for compressive strength and 1.88 gr/cm3 for specific gravity with two stages of elastic and plastic failures. The RUN-3 mixture was also used to produce cylindrical specimens and tensile strength was found to be 11.55 MPa while flexural strength in the transverse and lateral axis was 53.74 MPa, and 57.69 MPa respectively.

Smart construction material: Utilization of M−sand to mitigate environmental pollution and generalized mix design thereof

The insufficiency of conservative materials like cement, sand and aggregates becomes the main critical problem in civil engineering domain among the higher demand of best quality control infrastructure. This research paper is emphasized on fine aggregates (sand). Sand which is dredged from the river bank is unfavorable in favor of the environment due to the depletion of underground surface water table near the surface zone which included soil and rocks permanent saturation under the water. In this regard an experimental research has been conducted on M−Sand. The mix design procedure only with M−Sand has not been described in any design codes even for distinct value percentage of M−sand and grade of concrete. A generalized mix design procedure is developed here for 50% river sand and 50% M−sand to increase or decrease the quantity of M−sand in nearby future. A parametric study has been carried out for distinct value percentages of M−Sand. In this paper to show the impact of M−sand on river sand a mix design tests of M−25 grade concrete including river sand and replacement M−Sand as a fine aggregate in distinct values of i.e. 0.0%, 10%, 20%, 40%, 45%, 50%, 55%, 60%, 80% & 100% ratios have been conducted. It is observed that almost mechanical-chemical characteristics of river bank sand and crushed stone (manufactured) M−Sand are similar. Results are described here in graphical form to show the influence of M−sand and it is concluded that M−Sand can be utilized as a partial or completely replacement material in place of river sand with high compressive, tensile and flexural strengths of concrete cubes, cylindrical and beam specimens respectively. Results revels positive response to use M−sand to mitigate the environmental pollution.

Zonal disintegration phenomenon based on triaxial dynamic load test of hollow cylindrical sandstone specimens

Zonal disintegration phenomenon based on triaxial dynamic load test of hollow cylindrical sandstone specimens