Cylindrical Specimens Research Articles

Determination of the Strength Characteristics of Sporosarcinal -PasteuriiConcrete

The strength characteristics ofSporosarcinal Pasteuriiconcrete (S. Pasteurii concrete)was investigated.To achieve this aim, the suitability of the materials used for concrete specimens weretested before the compressive, tensile and flexural strength of the S.Pasteurii concrete was investigated.Bacteria concentration of 0, 0.5, 2, 4 and 6OD was mix with the concrete. The water cement ratio adapted was 0.5.For the compressive strength, three cubes of size 150 x 150 x150mm was crushed for each curing day of 1, 3, 7,14, 28 and 56 days. The average compressive strength was obtained as the compressive strength of the concrete at eachcuring age. For the split tensile strength, three cylindrical specimen of size 100mm x 200mm was used at each day to obtain the strength at 7, 14, 21 and 28 days. The average tensile strength was obtained and for the flexural strength, three beam samples of 100 x 100 x 450mm was used at each curing day of 7, 14, 21 and 28days to obtain the average flexural strength.All the properties of the materials used for the concrete production met the standard requirement of the relevant code of practice. The compressive, tensile and flexural strength of S. Pasteurii concrete was improved in comparison with the control concrete. The percentage increase of the compressive strength at 28days are 17.76%, 19.72%, 25% and 4.04% for 0.5OD, 2OD, 4OD and 6OD respectively.The highest tensile strength was increased by 16.24% and obtained when 0.5OD bacteria concentration was used and cured for 14days. The flexural strength of S. Pasteurii concrete was improved by 44.44%, 8.89%,47.40% and 8.52% for 0.5OD, 2OD,4OD and 6OD respectively at 28 day of curing.

Nopal extract and aloe vera to improve structural concrete exposed to saline environments

The objective of this study was to examine the impact of Nopal (N) and Aloe Vera (AV) on the physical and mechanical properties of structural concrete in saline environments. Concrete with a compressive strength of 245 kg/cm² was used, adding N and AV extracted from natural plants in the study region. A total of 130 cylindrical specimens, 40 prismatic specimens, and 10 fresh mix samples were analyzed. Percentages of Nopal (2%, 6%, and 10%), Aloe Vera (0.5%, 1.5%, and 3%), and mixed (2%N + 0.5%AV, 6%N + 1.5%AV, 10%N + 3%AV) were added based on the weight of the cement. The control group contained no additives. The best results were obtained with the 2%N + 0.5%AV samples, with the highest compressive strength of 443.4 kg/cm² at 28 days and 445.4 kg/cm² at 56 days, a tensile strength of 41.4 kg/cm² at 28 days, a flexural strength of 66.4 kg/cm² at 56 days and 70.9 kg/cm² at 90 days of curing. The corrosion resistance decreased by a maximum of 0.22 mm/year. The physical and mechanical properties were optimized with the proportion of 2%N + 0.5%AV, indicating that the mixing matrix becomes more compact, and the carbonation rate is reduced, resulting in greater strength and durability.

Flexural strength of beam concrete with PET plastic addition and 30% copper slag

The development of renewable concrete materials has long been carried out by researchers about concrete to find alternative materials that allow it to be used as a substitute material for the use of concrete. Alternative materials can be obtained from waste materials or wasted materials from industrial products and how the manufacture of concrete is said to be environmentally friendly concrete. Copper slag is the result of copper processing waste in the form of sandy material and plastic with various types of PET, that can be found in household waste. Therefore, the objective of this study is to calculate the technical strength of the concrete beam with additional material in the form of 30% copper slag and variations of the addition of PET plastic. This research was conducted experimentally with compressive strength testing with cylindrical specimens 10 cm in diameter and 20 cm in height and beam testing with a size of 15 cm x 15 cm and a length of 53 cm according to bending beam testing standards without reinforcement. Variations of PET plastic used in concrete mixtures with 30% copper slag are 0.3%, 0.6%, and 0.9%. The results of this study show that the compressive strength value of concrete with copper-slag of 30% and PET plastic of 0.6% gives a maximum compressive strength value of 27.5 MPa, and the value of flexural strength obtained is 5.03 MPa. The optimum deflection after adding PET plastic occurs in a mixture of 0.6% PET plastic which is 0.45.

Rutting performance of asphalt mixtures containing treated RCA and reinforced by carbon fibers

This study examined the rutting performance of hot asphalt mixtures containing treated RCA and reinforced by carbon fibers. The methodology involved substituting RCA instead of coarse virgin aggregates in the several percentages (20, 40, 60, 80, and 100%) that were treated by being submerged for 24 hours in an acetic acid solution with a concentration of 0.1M. Carbon fibers were added in several percentages of 0.15, 0.25, and 0.35% by the entire weight of the mix to produce cylindrical specimens (4×2.5 inches) for evaluating the Marshall and volumetric properties, and rectangular slabs (30×40×5 cm) for evaluating rutting resistance. The study finds, that incorporating RCA and carbon fibers did not substantially affect the volumetric characteristics of asphalt mixtures, but Marshall's stability increased. The combination containing 60% RCA and 0.35% carbon fibers showed the greatest increase in Marshall stability, which was 35.81% over the control mixture. The addition of RCA led to a reduction in the rutting performance, whereas the addition of carbon fibers increased it, as seen by a decrease in rutting depth. The combination incorporating 40% RCA and 0.35% carbon fibers exhibited a minimum rutting depth of 40.64% lower than the control mixture. The combination incorporating 20% RCA and 0.35% carbon fibers exhibited the maximum level of dynamic stability, which was 1.64 times greater than the control mixture.

Assessing Fatigue in Materials with Small Defects: A New Multiaxial Model Based on Principal Stress Amplitudes

A new multiaxial fatigue model for materials containing small defects proposed by the authors is presented, which one can be considered as a modification of the SWT model. This new model relates the fatigue limit of the material obtained from the √area parameter with values associated with the principal stresses. These values are the amplitude of the principal stresses and the maximum principal stress observed. The amplitude value associated with the principal stresses is defined by using the Maximum Variance Method. This amplitude only can be easily obtained under uniaxial loading conditions, but its calculation for torsion, proportional and non-proportional multiaxial loadings is not trivial. Therefore, the calculation of the principal stress amplitude posed a challenge not yet addressed by other authors. The multiaxial fatigue model was evaluated with experimental data from AISI 4140 steel, with several different loading conditions, including uniaxial loading, combined loads in in-phase and out-of-phase configurations. In addition, two types of specimens were used: smooth cylindrical specimens and specimens with a surface micro hole. Comparing the experimental data with the prediction of the new model it was observed that the predictions are slightly conservative with average error not exceeding 6%.

Effects of Different Surface Treatments on Flexural Strength of Zirconium Oxide Cores

Objective: The aim of this study was to investigate the effect of different surface treatments on the biaxial flexural strength of zirconia and to determine phase transformation before and after sintering. Materials and Methods: 150 cylindrical specimens with the dimensions 15 mm diameter and 1,3 mm height were obtained from semi-sintered Y-TZP blocks. These specimens were randomly separated into subgroups; sandblasting, Er:YAG laser, Nd:YAG laser, Er:YAG laser+sandblasting, Nd:YAG laser+sandblasting, fine grain bur, coarse grain bur. Half of the semi-sintered Y-TZP samples were treated before sintering and the others were treated after the sintering procedures. No treatment was performed in control group. Biaxial flexural strength test was performed to all samples. X-ray diffraction analysis (XRD) were performed to identify transformed monoclinic phase. The data were analyzed by Kruskal-Wallis, Man Whitney U test and Wilcoxon test (p<0,05). Results: Specimens that were treated before sintering had lower biaxial flexural strength. The highest biaxial flexural strength values in all groups were seen in sandblasting groups and the lowest in grinding groups. According to the XRD analysis the highest phase transforme was determined in sandblasting groups. Sandblasting, Er-YAG laser+sandblasting and Nd-YAG laser+sandblasting were greatly increased the biaxial flexural strength of all the surface treatments after sintering. All the sandblasting treatments were found more monoclinic phase was found than other groups. Conclusions: Surface treatments were found to affect both the mechanical properties and phase changes of zirconia.

Abrasive resistance and microhardness of self-adhesive (Surefil one) and conventional bulk fill composites: An- in vitro study.

Aims and objectives: To evaluate abrasive resistance and microhardness of self-adhesive Surefil one and conventional bulkfill composites Beautifil bulk restorative and Filtek one bulk fill restorative. Materials and Methods: For the abrasive resistance test, thirty composite discs (4 mm hieght×8 mm width) in each group (n=10) were fabricated. GI: Beautifil bulk restorative, GII: Filtek One Bulk fill restorative and GIII: Surefil one self-adhesive. By placing the material in a mold in a single increment then curing. A custom-made toothbrush simulator was employed for wear testing. The samples weighted before and after the brushing to measure the weight loss. For the microhardness test, thirty cylindrical specimens (6 mm× 8 mm) (n= 10) were fabricated to assess the microhardness, top and bottom surfaces were tested using Vicker Hardness test. The results were analyized with a one-way ANOVA test, the post-hoc comparisons were examined in Tukey test. Results: Abrasive Resistance results, Surefil one (9.52gr) and Beautifil bulk (4.16gr) showed an increase in weight after brushing, while Filtek one bulkfill (-0.85gr) showed a decrease in weight.Microhardness test results, Beautifil bulk showed the highest number of VH (74.83) followed by Surefil one (70.61) and Filtek one bulkfill (62.95). Conclusion: Beautifil bulk was more resistant to abrasion in comparison to Surefil one self-adhesive and One bulk fill. The great weight loss was observed in One bulk fill. Great weight gain was observed in Surefil one self-adhesive. Beautifil bulk showed the highest VH number compare to Surefil one self-adhesive and One bulk fill. Filtek one bulk fill showed low resistance and low hardness number. Keywords: Bulk fill, Self-adhesive, Abrasive resistance, Microhardness Composite, Surefil one

VARIATION OF SUPERPLASTICIZER AMOUNT ON CONCRETE COMPRESSIVE STRENGTH

This study aims to determine the effect of the addition of superplasticizer in concrete mixtures on compressive strength. To achieve this goal, a laboratory study was conducted using 12 cylindrical specimens with a diameter of 150 mm and a height of 300 mm. There are three variations of superplastcizer addition and one variation of concrete without superplastcizer addition as control. The concrete cylinders were tested at 14 days. The coarse aggregate used is a combination of 2 types of aggregates, namely Banjarmasin Stone (50%) and Merak Stone (50%).From the test results, the average compressive strength of concrete without using superplasticizer was 27.10 MPa. The compressive strength of concrete using superplasticizer (mix design results) is 37.18 MPa. For concrete that uses less superplasticizer (reduced by 1% from the mix design results) results in a compressive strength of 34.06 MPa. While for concrete that uses more superplasticizer (increased by 1% from the results of the mix design) gives a compressive strength of 37.02 MPa. Concrete that uses superplasticizer has a greater compressive strength value than concrete without superplasticizer

Strain-dependent-deformation property of Gyeongju compacted bentonite buffer material for engineered barrier system

This study aims to investigate the strain-dependent-deformation property of Gyeongju bentonite buffer material. A series of unconfined compressive tests were performed with cylindrical specimens prepared at varying dry densities (ρd = 1.58 g/cm3 to 1.74 g/cm3) using cold isostatic pressing technique. It is found that as ρd increase, the unconfined compressive strength (qu), failure strain, and elastic modulus (E) of Gyeongju compacted bentonite (GCB) increases. Normalized elastic modulus (Esec/Emax) degradation curves of GCB specimens are fitted using Ramberg-Osgood model and the elastic threshold strain (εe,th) is determined through the fitted curves. The strain-dependency of E and Poisson's ratio (v) of GCB were observed. E and v were measured constant below εe,th of 0.14 %. Then, E decreases while v increases after exceeding the strain threshold. The Esec/Emax degradation curves of GCB in this study suggests wider linear range and higher linearity than those of sedimentary clay in previous study. On top of that, the influence of ρd is observed on Esec/Emax degradation curves of GCB, showing a slight increase in εe,th with increase in ρd. Furthermore, an empirical model of qu with ρd and a correlation model between qu and E are proposed for Gyeongju bentonite buffer materials.

Effect of Granular Waste Compact Disc on Bond Strength between Steel Bars and Surrounding Concrete

In recent decades, researchers have tried to use waste materials as a partial or complete replacement of the gravel ingredients of concrete to reduce environmental impact. One of these materials is electronic waste. The problem of this disposal material, particularly outdated CDs and DVDs, has turned out to be serious. In this study, 36 pull-out cylindrical shape test specimens were used to conduct an ASTM C234-91A-compliant pull-out test to measure the bonding behavior and strength between three sizes of steel bars and concrete with different embedded lengths, including waste disc shreds (CD and DVD) as a partial substitute for fine aggregate. Four groups of modified concrete specimens with different percentages of disc shreds as partial replacements for sand were prepared. The ratio of cement:sand+disc:coarse aggregate:water was 1:2:2.5:0.4. The disc shreds were utilized to substitute partially for fine aggregate in four different weight percentages: 0%, 4%, 8%, and 12%; nevertheless, the cement-to-sand ratio was consistently 2. Results demonstrated that the bond strength is considerably influenced by the bar diameter and the disc shreds (CDs and DVDs) used as a partial replacement for fine aggregate. The bond strength behavior of the modified concrete with disc fibers is comparable with that of traditional concrete. The ACI-318 Code for the bond strength of ordinary Portland cement concrete was modified to calculate the bond strength of this new kind of disc concrete.

Detecting meso-damage and subsurface cracks in a hard rock using frequency-modulated thermal wave imaging (FMTWI)

Mines, tunnels, and hillside roadways that are subjected to high levels of stress are prone to massive and violent occurrences of rock failures. It results in a multitude of irreversible consequences, including the loss of human lives. Nevertheless, preceding rock failures, the development of micro and macrocracks, which are sometimes not discernible on the surface, takes place. Subsurface cracks indicate the degradation of rock and can be employed as a means to anticipate occurrences of rock failures and bursts. Therefore, the utilization of subsurface imaging techniques for rocks facilitates the estimation of the true strength of the rock mass. Nevertheless, in many instances, rock masses are not easily reachable, posing difficulties for standard techniques such as ground-penetrating radar or computed tomography (CT) scan imaging, to identify the cracks. Hence, this research endeavours to explore the feasibility of employing frequency-modulated thermal wave imaging (FMTWI) for identifying subsurface cracks and their coalescence in hard rocks through the utilization of numerical simulation and experimental methods. A model was constructed using the finite element method wherein artificial cracks were intentionally introduced into a cylindrical granite specimen based on the CT scan data acquired during the meso-damage analysis. The thermograms obtained were subjected to pre-processing and post-processing techniques, and afterwards compared with the CT scan images. The FMTWI tests were conducted in the laboratory to calibrate and validate the simulation results. The findings derived from the analyses of temperature profiles and thermograms indicate that this particular technology is a promising one and offers several advantages in comparison to alternative methods for detecting micro- or macrocracks in deep mines and tunnels.

Mechanical strength and Life Cycle Assessment (LCA) of soil-cement: comparison between mixtures of soil with ASTM type III cement, LC3, and the incorporation of by products and agroindustrial residues

Soil stabilization with binders is based on the binder action on soil particles, in turn causing an improvement in the mechanical behavior of the soil. Thus, this study aims to analyze the mechanical and environmental properties of soil-cement mixtures using Portland ASTM type III cement as binders and comparing to LC3 (Limestone Calcined Clay Cement), as well as incorporating extra raw materials such as silica fume, fly ash, sugarcane bagasse ash (Saccharum officinarum L) and açai seed ash (Euterpe precatoria Martius). The mixtures of soil, binder, extra raw materials were performed manually, and the cylindrical specimens (100 mm internal ø) were molded based on the AASHTO Normal Test. The results showed that the highest values of compressive strength ranged between 10 and 11 MPa, which were recorded for reference, soil-LC³ and soil-LC-açai seed ash mixtures. Life Cycle Assessment (LCA) was performed using the CML 2001 method with the aid of the OpenLCA software. Additionally, it was observed that the main emissions and consequences for the environment were from mixtures containing higher clinker contents.

The Flue Gas Desulfurization Gypsum Applications in Production of Eco-Friendly Cementitious Matrices

Portland cement is one of the most manufactured materials in the world. The worldwide cement industry accounts for at least 5-8% of the anthropogenic CO2 emissions and therefore is an important sector for CO2-emission mitigation strategies to limit global warming. One of the strategies for reducing the carbon footprint of the cement industry is replace traditional Portland cement with other solid wastes. In the present study, the influence of the application of flue gas desulfurization gypsum (FGD gypsum) generated from coal-fired power plant in construction mortar was investigated. Cylindrical specimens were molded with Portland cement type CPII-F 32, sand and 0%, 25%, 50% and 75% amounts of FGD gypsum. After curing time of 1, 3, 7, 28 and 91 days, the cementitious materials were characterized mechanically by axial compressive strength, setting time and slump. The pastes in the age of 28 days were further characterized by X-ray diffraction with Rietveld analysis. Results showed that FGD gypsum can be used as a substitute for cement as a setting retarder in an amount of up to 25%, and as an accelerator in an amount of 75%, being necessary dosage of the specific traces of the materials depending on the purpose of its use.

Shear bond strength of the ceramic veneer to additively manufactured titanium.

The objective of this in vitro study was to evaluate the shear bond strength between the ceramic veneer and additively manufactured titanium with different surface treatments, and to compare with milled titanium. Also, to characterize the surface and the presence of an α-case layer of additively manufactured and milled titanium. Sixty additively manufactured titanium grade 23, and 20 milled titanium grade 4 cylindrical specimens were divided into four groups based on surface treatments, air-particle abrasion and grinding. After ceramic veneering half of each group were thermocycled. The bond strength was analyzed using a shear bond strength test. The surfaces were analyzed using interferometry and scanning electron microscopy. The grinding procedure and air-particle abrading pressure had no significant effect on the shear bond strength (p = .264 and p = .344). Thermocycling showed a tendency towards an effect but not significant (p = .052). The group with the highest air-abrading pressure showed the highest surface roughness. No presence of an α-case layer was detected in any of the groups. Additively manufactured titanium grade 23 may be veneered with ceramics without prior grinding of the surfaces.

Comparative analysis of three different types of self-healing concrete via permeability testing and a quasi-steady-state chloride migration test

Concrete is the most used construction material in the world and with the growing world population, the demand for housing and infrastructure keeps increasing. Due to its low tensile strength, concrete cracks easily and these cracks have a negative effect on the durability. Different studies have already been conducted on the development of self-healing concrete, which has the ability to heal its own cracks. Unfortunately, due to a lack of standardized test methods, the boundary conditions in these studies are often different, making it difficult to do an accurate comparison. In this research, three different healing agents are tested using the same test methods under the same boundary conditions: a powder of organic/inorganic composite material (WM), solidified calcium sulfoaluminate capsules (SMU) and bacterial pellets (KU). The healing efficiency of the agents is tested with (1) a low-head water flow test on prismatic specimens cracked in a three-point bending test with subsequent active crack width control, (2) a Korean water permeability test on cylindrical specimens cracked by a Brazilian splitting test, (3) a chloride diffusion test and (4) a quasi-steady-state chloride migration test. The results showed that WM performed superior with respect to the reference mix and the other healing agents in the two water permeability tests and the quasi-steady-state chloride migration. The performance of SMU and KU was depending on the healing condition. When fully saturated during healing, the KU specimens had a good behaviour and SMU performed poorly. For the cylindrical specimens, with the specimen partly immersed in water, SMU and KU had a similar performance which was better in comparison to the reference.

Comparison of tensile properties and porcelain bond strength in metal frameworks fabricated by selective laser melting using three different Co-Cr alloy powders

Statement of problemThe selective laser melting (SLM) manufacturing technique has been widely employed to produce Co-Cr dental metal frameworks. The selection of Co-Cr alloy powders has the potential to influence the microstructure and tensile properties, consequently impacting the bond strength of the metal-porcelain. However, limited information is available regarding the effect of Co-Cr alloy powder on these properties when all other factors remain consistent. PurposeThe purpose of this in vitro study was to assess how the choice of Co-Cr alloys during SLM manufacturing influences the microstructure, tensile properties, and bond strength of metal-ceramic combinations. Material and methodsThree different Co-Cr alloy powders, Co-Cr-Mo, Co-Cr-Mo-W, and Co-Cr-W were selected in this study. The powder characteristics and chemical compositions were analyzed using a scanning electron microscope (SEM) and energy dispersive X-ray (EDX) analysis, respectively. Subsequently, 12×12×15-mm cube specimens, cylindrical tensile test specimens, and 25×3×0.5-mm metal strips were fabricated using the SLM technique. Microstructural investigations of the cube specimens were conducted after metallographic preparation using SEM. The cylindrical tensile specimens (n=8) from each composition were subjected to tensile tests at a deformation rate of 0.5 mm/min. Following the application of ceramic to the metal specimens (n=10) in each group, the strength of the metal-ceramic bond was evaluated through a 3-point bend test conducted at a crosshead speed of 1 mm/min. Mechanical properties obtained from the tensile tests and bond strength values were statistically analyzed using a one-way ANOVA and Tukey post hoc comparison tests (α=.05). ResultsMelt pool boundaries, columnar and equiaxed grains, and precipitates were observed in the microstructures of 3 different alloys produced by SLM. The Co-Cr-Mo-W alloy had more uniformly dispersed and finely distributed precipitates compared with other alloy compositions. The Co-Cr-Mo-W alloy had exhibited the highest yield strength (1068.0 ±41.2 MPa) and ultimate tensile strength (1263.4 ±10.7 MPa) while showing the lowest ductility under the tensile tests (6.1 ±0.9%) among all 3 alloys. Significant differences in the tensile mechanical properties were observed in the alloys except between the yield strength of the Co-Cr-Mo and Co-Cr-W alloys. The highest elongation (8.9 ±1.2%) was seen in the Co-Cr-Mo alloy. However, no significant differences were detected regarding the bond strength of all 3 groups (P>.05). The mean bond strength values were approximately 42 MPa for all the alloys. ConclusionsThe results indicate that the selection of different Co-Cr alloy powders used in SLM production may influence both microstructure and tensile properties. However, the strength of the metal-ceramic bond of Co-Cr alloys remained unaffected by this selection.

DEFORMATION FEATURES OF EMBEDDED MATERIALS UNDER COMPRESSION CONDITIONS

Purpose. The purpose of the article is t o study the deformation characteristics of the backfill materials made of crushed rock of different granulometric composition under compression conditions to assess the stability of the side rocks in a coal massif with preparatory workings when selecting the parameters of protective structures. Methods. Compression tests were carried out in the laboratory to model the behaviour of crushed rock fill materials under load. Cylindrical specimens were subjected to axial static compression without the possibility of lateral expansion. The results. It has been experimentally established that the maximum value of the compaction coefficient of the crushed rock kс=1.57 is achieved under conditions of compression, when the relative change in the volume of the source material is 35-36% and the relative void is 5-6%. Under such conditions, the ultimate compressibility of the deformable body is achieved at its relative deformation λ = 0.36 and the presence of particles of different sizes (diameters) in the total volume of the rock layer (before compression). At the minimum value of the compaction coefficient kс=1.14, which corresponds to the small fraction of the crushed rock, the relative change of the void is 1.5%. For a large fraction of crushed rock at kс=1.43, the relative change in voids is 6.2%. This situation is associated with the destruction of rock particles and the reduction of voids between them. Compliance with certain requirements for backfill materials made of crushed rock, taking into account its particle size distribution, increases the efficiency of using the backfill of the excavated space. It is advisable to evaluate the bearing capacity of backfill materials by the value of the compaction coefficient of crushed rock. Scientific novelty. A functional relationship between the change in the specific potential strain energy and the relative deformation of the rock layer has been established, which allows us to estimate the degree of compaction of crushed rock under compression. Practical significance. To ensure maximum compaction of the crushed rock when using partial or complete backfilling of the worked-out space used for the protection of mine workings, it is advisable to use a heterogeneous (in terms of particle size) source material. Keywords: crushed rock, backfill material, stiffness, particle size distribution, compaction, deformation, compression.

Influence of Different Factors on Permanent Deformation of Hot Asphalt Concrete Mixtures

Abstract The performance of flexible pavements is significantly impacted by the permanent deformation (rutting) of asphalt pavements. The research aims was to evaluate the permanent deformation of asphalt mixtures under different conditions. To achieve this aim, 108 cylindrical specimens have been prepared and tested under repeated loading in uniaxial compression mode. Five factors were considered in this research. They include testing temperature, loading conditions (stress level and duration), and mixture properties (bitumen type and content). The permanent deformation is evaluated in term of the following parameters, permanent micro strain εp, resilient micro strain εr, initial permanent strain (intercept, a), accumulation rate of permanent deformation (slope, b), rate of decrease in permanent deformation α and constant of proportionality between permanent and elastic strains Mu. The test results showed that the εp and a are increased as the testing temperature increased. In addition, the εp value for load duration of 0.4 s is 1.64 times the value for 0.1 s. Finally, the findings showed that the resilient response of the material is comparatively more sensitive to bitumen content than the plastic response. Furthermore, the rutting resistance is highly affected by the variables considered in this research.

Microarchitecture Alternations of Osteochondral Junction in Patients with Osteonecrosis of the Femoral Head.

The study was aimed to investigate microarchitecture of osteochondral junction in patients with osteonecrosis of the femoral head (ONFH). We hypothesis that there were microarchitecture alternations in osteochondral junction and regional differences between the necrotic region (NR) and adjacent non-necrotic region(ANR) in patients with ONFH. Femoral heads with ONFH or femoral neck fracture were included in ONFH group (n = 11) and control group (n = 11). Cylindrical specimens were drilled on the NR/ANR of femoral heads in ONFH group and matched positions in control group (CO.NR/ CO.ANR). Histology, micro-CT, and scanning electron microscope were used to investigate microarchitecture of osteochondral junction. Layered analysis of subchondral bone plate was underwent. Mankin scores on NR were higher than that on ANR or CO.NR, respectively (P < 0.001, P < 0.001). Calcified cartilage zone on the NR and ANR was thinner than that on the CO.NR and CO.ANR, respectively (P = 0.002, P = 0.002). Tidemark roughness on the NR was larger than that on the ANR (P = 0.002). Subchondral bone plate of NR and ANR was thicker than that on the CON.NR and CON.ANR, respectively (P = 0.002, P = 0.009). Bone volume fraction of subchondral bone plate on the NR was significantly decreasing compared to ANR and CON.NR, respectively (P = 0.015, P = 0.002). Subchondral bone plate on the NR had larger area percentages and more numbers of micropores than ANR and CON.NR (P = 0.002/0.002, P = 0.002/0.002). Layered analysis showed that bone mass loss and hypomineralization were mainly on the cartilage side of subchondral bone plate in ONFH. There were microarchitecture alternations of osteochondral junction in ONFH, including thinned calcified cartilage zone, thickened subchondral bone plate, decreased bone mass, altered micropores, and hypomineralization of subchondral bone plate. Regional differences in microarchitecture of osteochondral junction were found between necrotic regions and adjacent non-necrotic regions. Subchondral bone plate in ONFH had uneven distribution of bone volume fraction and bone mineral density, which might aggravate cartilage degeneration by affecting the transmission of mechanical stresses.

Pemanfaatan Limbah Keramik Sebagai Bahan Alternatif Campuran Agregat Kasar Pada Beton

In every construction and renovation project, there is often waste that is rarely reused. The utilization of ceramic waste as a coarse aggregate in concrete can be an interesting alternative because ceramic waste shares characteristics and properties similar to coarse aggregate materials, such as hardness, and has the potential to reduce negative environmental impacts and the depletion of raw materials. Therefore, this research adopts an experimental method at the laboratory of the National Education University in Denpasar by creating five different variations of cylindrical specimens, each with three samples. The ceramic waste variations used are 0%, 10%, 15%, 20%, and 40%. By using an FAS value of 0.6, the slump value was obtained, where the larger the ceramic waste mixture value, the smaller the slump value, as this occurs due to the water absorption value in the ceramic waste being 10.51%. However, despite this, the slump value still falls within the planned range of 5.0 cm to 12.0 cm, and for the planned compressive strength value, which is 175 kg/m2, the highest average concrete strength value is found in the 0% variation, which is 16.01 MPa or equivalent to 192.83 kg/cm2. The concrete with a 10% variation has a compressive strength of 15.21 MPa or 183.25 kg/cm2, the concrete with a 15% variation has a compressive strength of 15.01 MPa or 180.82 kg/cm2, the concrete with a 20% variation has a compressive strength of 13.64 MPa or 164.38 kg/cm2, and the concrete with a 40% variation has a compressive strength of 9.87 MPa or 118.96 kg/cm2. This research can be used as additional literature or as an evaluation material for further research.