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Sewage sludge incinerated ash is discharged as waste. Those are increasing with progress of a sewage enterprise every year. However, the reservation of the last disposal place for reclaiming the generated incineration ash is becoming quickly difficult. In this situation of sewage sludge processing, it is very important to promote more reducing and development of new reusing method. Recently, in the construction industry, reusing technology that was used sewage sludge incinerated ash as aggregate for concrete products is developed. But there are many unknown points in the performance and durability of concrete.

In this study, sewage sludge incinerated ash is used instead of natural aggregate for concrete. It is investigated about fresh characteristics, chloride content, strength, resistance to frost damage and drying shrinkage of concrete using sewage sludge incinerated ash. As the results of this research, the compressive strength increases with ratio of sewage sludge incinerated ash. And the relationship between the compressive strength and the dynamic modulus of elasticity can be comparatively expressed as the linear relationship. If this concrete includes proper air content, the resistance to frost damage is enough. The drying shrinkage is become larger with increase of substitute rate of sewage sludge incinerated ash.

The fractional quantitative computed tomography (fQCT) to determine both quantity and distribution of bone mineral was evaluated based on the mechanical properties of trabecular bone. Using quantitative computed tomography (QCT), bone mineral density was measured at 46 areas from 5 bovine tibias. Subsequently, fQCT was measured by the proportion of pixels showing a bone mineral density greater than 290 mg/ml. Based on the mechanical properties of the bone specimens, the QCT and the fQCT were compared. The fQCT showed a significant correlation with the compressive strength with superiority to the QCT.

The thickness of corroded concrete layer and the compressive strength of prisms under the action of sulfate and chloride salt were investigated by ultrasonic test and compression test, respectively. The results show that under the single action of sulfate, the strength of concrete experienced two stages: a slow growth stage and a rapid descent stage. Correspondingly, under the combined action of sulfate and chloride, the concrete strength experienced another two stages: a slow growth stage and a slow degradation stage. The existence of chloride inhibited the corrosion damage of concrete in a certain extent. It was found that higher concentration of chlorine salt would lead to a stronger inhibition effect. A good consistency was observed among corrosion layer thickness, compressive strength and X-ray diffraction results. The inhabitation of chloride to the sulfate corrosion of concrete was proved.

To meet the needs of underground anti-seepage projects such as landfills better, the anti-seepage slurry modified by sodium carboxymethyl cellulose (CMC-Na) was prepared through laboratory experiments on the basis of the preliminary study of PBFC anti-seepage slurry. The main material of the slurry is bentonite modified by sodium carboxymethyl cellulose, cement, fly ash and auxiliary materials such as sodium carbonate and polycarboxylate superplasticizer. The optimal ratio of the basic components of the anti-seepage slurry was optimized by the orthogonal test method. The permeability coefficient of the slurry was tested by the self-made constant head permeameter, and the age-resistant compressive strength was tested by the electronic press. The optimal mass ratio of each component of 1 liter slurry is: 20–22% bentonite, 20–22% cement, 16% fly ash, 0.15–0.2% sodium carbonate, 0.15–0.2% sodium carboxymethyl cellulose, 0.3% polycarboxylate superplasticizer. The permeability coefficient of the slurry consolidation body for 28 days is less than $1\times 10^{-8}$cm/s, and the unconfined compressive strength is 0.5–2.0 MPa. The performance indexes of the slurry are higher than those of the existing anti-seepage slurry, which can better meet the anti-seepage standard of urban landfill in China.

Poly-lactic Acid (PLA) is an environmentally friendly material with better stability in heat shrinkage than Acrylonitrile Butadiene Styrene (ABS), such as warping in 3D printing. This study focused on the enhancement of the mechanical properties of PLA filament for 3D printers through different heat treatment temperature and heat exposure time of PLA samples. The results showed that the highest flexural strength was recorded in the PLA sample that went through heat treatment at $130^{\circ }\mathrm{\text{C}}$ and heat exposure time of 300 s. And it tended to decrease with temperature and time after this point. But it has higher flexural strength than neat PLA. The compressive strength showed the highest compressive strength through heat treatment at $140^{\circ }\mathrm{\text{C}}$ for 600 s. Because compressive strength has no threshold limit temperature in experimental temperature, compressive strength showed a tendency to increase with increasing heat exposure time and high temperature at same condition. This result showed that the heat treatment process affects the flexural strength and compressive strength and can be improved upon using appropriate heat treatment conditions.

We study experimentally the influence of mass fraction of L-20 hardener cold cure on mechanical properties of epoxy diane resin ED-20. We measure the hardness, tensile strength, bending strength and impact strength of resin at different values of the hardener mass fraction. It is found that the ratio hardener mass fraction of 1:0.9 leads to the highest values of the hardness, tensile strength, compressive strength and bending strength. The impact viscosity is maximum at the ratio hardener mass fraction of 1:0.8. The optimal ratio of a non-toxic safe hardener to the resin is derived based on obtained mechanical characteristics.

Foamed concrete possesses characteristics such as high strength-to-weight ratio and low density, and widely used to reduce dead loads on the structure and foundation, contributes to energy conservation, and lowers the labor cost during construction. In this paper, the objective is to propose prediction relation for the compressive strength of foamed concrete by fractal theory. A theoretical relation was derived for the compressive strength relating to porosity based on the fractal model for foamed concrete. The proposed relation stands out compared to empirical model since it employs easily measurable parameter, the fractal dimension of porous structure in foamed concrete. The fractal dimension of porous structure can be calculated from the scaling law of the compressive strength of foamed concrete. The fractal model for porous structure serves as a simple and effective tool for predicting the compressive strength of foamed concrete because of its ease in application. The prediction relation of the compressive strength developed in this paper is found to match well with the measured strength.

Although there is much discussion on the evaluation of the dissemination ability of sci-tech periodicals, there is no perfect evaluation method system in the existing studies, and especially the evaluation model is not operable. This paper converts the qualitative evaluation of the dissemination ability into a multi-criteria decision-making problem, and proposes a research method of sci-tech periodicals dissemination ability based on hesitant fuzzy linguistic. Firstly, this paper systematically combs the research progress of the evaluation of dissemination ability of sci-tech periodicals and multi-criteria decision-making under uncertainty. Then, a multi-criteria decision-making method based on hesitant fuzzy linguistic correlation is proposed, which fully considers the preferences of decision makers and effectively integrates the incomplete compensation hypothesis. Finally, the periodical topic planning, knowledge popularization recognition, publishing market operation ability and supporting discipline construction are selected as empirical conditions to verify the applicability and effectiveness of the model. At the same time, in order to make the empirical results more objective and scientific, the density clustering results of the questionnaire are used instead of the decision-maker membership score in the evaluation of dissemination ability. Theoretical analysis and empirical results show that the method proposed in this paper can be effectively applied to the evaluation of the dissemination ability of sci-tech periodicals.

Expanded flyash clay aggregate (EFCA) is a promising sustainable alternative to coarse aggregate in concrete. Concrete specimens with conventional natural aggregate and EFCA as coarse aggregates were prepared separately and exposed to elevated temperatures of range 200°C, 400°C, 600°C and 800°C, observed for surface changes like change in color and formation of visual cracks, tested for loss in mass, strength and water absorption, analyzed by XRD for mineralogical changes through variation in chemical composition. Specimens when exposed up to 400°C has not shown any notable changes in the above property, beyond which strength of both specimens started to decrease gradually, at higher temperature EFCA mix showed loss in mass of 4.5% compared with normal concrete, visual observation of specimen surface showed EFCA specimens sustained cracks till 600°C. EFCA mix also showed a constant rate of water absorption. Concrete with EFCA showed consistently higher compressive strength at higher temperature up to 400°C and found satisfactory in all aspects tested made EFCA as coarse aggregate in concrete as a sustainable alternative to natural aggregates.

In this work, the experimental investigation of the surface integrity and biomechanical properties of the superficial layer obtained by wire electrical discharge machining (W-EDM) of Ti-6Al-4V alloy for biomedical application has been carried out. The surface morphology and elemental composition of the superficial layer have been investigated by field-emission scanning electron microscope (FE-SEM) and energy dispersive X-ray spectroscopy (EDS) techniques. The micro-mechanical behavior in terms of compressive strength and surface hardness was studied using the micro-pillar and nano-indentation technique. The corrosion resistance and in vitro bioactivity have been investigated using electrochemical and immersion test. Morphological analysis showed that surface morphology and superficial layer thickness were affected by peak current, pulse-duration and pulse-interval. The niobium (Nb)-rich layer was developed in superficial layer zone. The low peak current (3–6A), low pulse-duration (5–10$\mu$s) and high pulse-interval ($>45\mu$s) have been recommended for better surface morphology and thin superficial layer (ranging from 4–6$\mu$m) free from surface defects. The micro-pillar and nano-indentation results showed that the superficial layer comprised of a brittle structure that improved the mechanical properties of the layer and the compressive strength was measured to be 1198 MPa. The corrosion resistance analysis revealed that the Nb-rich layer in the superficial layer improved the corrosion resistance and bioactivity. Excellent apatite growth has been found in the W-EDM-processed zone. The W-EDM can be used for the biomedical industry as a potential surface engineering technique.

The strength of unidirectional composites is often lower in compression than in tension, making compressive strength an especially important design criterion. The compressive strength is sensitive to the presence of notches and stress gradients. Finite element analysis was used to determine the strain gradient at a shallow circular notch in one edge of a 0 degree carbon/epoxy composite specimen, and to predict failure due to a localized buckling instability. The specimen was first analyzed with a "global" model of the full specimen, and displacements along a curve near the notch were stored and used as boundary conditions for a more detailed "submodel" in the immediate vicinity of the notch. At the onset of instability, a displaced plot of the finite element model shows oscillations in the transverse direction along the arc of the notch, just off the centerline, which is essentially at the same location where failure initiated in the test specimens. Results are compared with experimental values for failure stress and notch strain concentration for a range of loading rates and test temperatures.

This paper presents the details of studies conducted on brick masonry units and wall panels. The investigation includes, compressive strength of brick unit, prisms, flexural strength evaluation, and testing of reinforced brick wall panels with and without opening. Nonlinear finite element analysis (FEA) of brick wall panels with and without opening has been carried out by simulating the actual test conditions. Constant vertical load is applied on the top of the wall panel and lateral load is applied in an incremental manner. The in-plane deformation is recorded under each incremental lateral load. Displacement ductility factors and response-reduction factors have been evaluated based on experimental results. From the experimental study, it is observed that fully reinforced wall panel without opening performed well compared to other types of wall panels in lateral load resistance and displacement ductility. In all the wall panels, shear cracks originated at loading point and moved toward the compression toe of the wall. The force-reduction factors of a wall panel with opening are much less when compared with fully reinforced wall panel with no opening. The displacement values obtained by nonlinear FEA were found to be in good agreement with the corresponding experimental values. The difference in the computed and experimental values is attributed to the influence of mortar joint which was not considered in FEA. The derived response-reduction factors will be useful for adopting elastoplastic design procedures for lateral forces generated due to earthquakes.

In recent years, significant research has been conducted to explore the use of 3D triply periodic minimal surface (TPMS) structures for their exceptional vibrational damping properties and their ability to provide a continuous, smooth surface. The emergence of 3D printing has enabled the application of TPMS structures in fields such as medicine and aviation. In civil engineering, the compressive capacity of structures is a fundamental parameter in structural design. To evaluate the potential of porous TPMS structures in civil engineering, we have designed and manufactured four types of Skeletal-TPMS units using Stereolithography (SLA) technology. Axially loaded tests and nonlinear finite element method (NFEM) simulations have been performed to investigate the compressive strength and stiffness of the units. Our findings indicate that compared to solid blocks, the compressive strength of Skeletal-TPMS units decreases by 71.3% to 82.6%, and the stiffness decreases by 64.9% to 79.2%. The Skeletal-SP units show better compressive resistance than Skeletal-IWP units. This study provides new valuable insights for structural design and applications using TPMS structures in civil engineering.

In order to investigate the structure and mechanical characteristics of cattle horns, the microstructures of the keratin shell and bone core were examined by scanning electron microscopy, and a series of mechanical tests were performed by the tension-compression test machine and pendulum impact test machine. Results showed that the keratin shell was a laminated structure stacked by keratin protein slices, and the bone core was a light-weight porous material with pores randomly distributed in the longitudinal direction. The ultimate tensile strength of the keratin shell diminished gradually from distal to middle to proximal parts with the values of 162, 125 and 85 MPa, respectively. The ultimate compressive strength of keratin shell and bone core in the longitudinal direction was higher than that in the transverse. The moisture could cut down significantly the mechanical characteristics of keratin shell and bone core. The shock toughness of the keratin shell was 4.9 J/cm², which was 7 times as large as that of the bone core. It can be concluded that cattle horn is a graded biological material with outstanding mechanical characteristics. The moisture, location and direction of the sampling have a significant effect on the mechanical characteristics of cattle horns. Compared with the bone core, the keratin shell has a better crashworthiness performance.

We investigated the compressive strength of PAN-based carbon fibers containing both amorphous and crystalline structures using molecular dynamics simulations. In addition, we investigated the buckling behavior of graphene and graphite crystals under compressive loading. The calculated buckling stresses of those crystals with different aspect ratios agree well with the results by the Euler's buckling theory. We finally found that the compressive strength of the PAN-based carbon fiber with a large amount of amorphous structures was 11 GPa. Moreover, a fracture of the PAN-based carbon fiber begins due to the buckling of carbon layers in crystallites, and propagates with the shear slipping in the crystallites. On the other hand, the compressive strength of the carbon fiber with a small amount of amorphous structures was only 2 GPa. Thus, it was found that the amorphous structure significantly affects the compressive strength of PAN-based carbon fibers.

The concrete strengthening additive based on the multi-walled carbon nanotubes was synthesized under mild conditions through a radical polymerization route by the reaction of oxidized nanotubes with maleic anhydride and $\alpha$-nonene monomers. The nanotubes used as the main reinforcing component of the additive were synthesized by catalytic chemical vapor deposition (CCVD) using Fe-Co/Al₂O₃ as the catalyst. The resulting nanocomposite was characterized by structural and surface morphological aspects via transmission electron microscopy (TEM), scanning electron microscopy (SEM), FTIR, XRD and Raman techniques. Investigation of mechanical properties revealed that the obtained nanostructure is an appropriate additive material for concrete strengthening purposes with about 51.3% strengthening potential.

The bearing capacity and ductility of confined concrete can be greatly increased by the confinement of confining material. To better study the mechanical behavior of confined concrete, this paper presents the yield criterion of confined concrete, based on the static equilibrium condition, the unified compressive strength model of confined concrete is established. The model captures the character of confined concrete, the effects of confinement effect ratio, the compressive strength of unconfined concrete, and the mechanical properties of confining material on the compressive strength of confined concrete were carefully analyzed.

The vertebral body cage has been widely used in anterior cervical discectomy and fusion to provide better stability and fusion rate. However, subsidence of a body cage into the vertebral body may cause severe problems. In this study, three-dimensional finite element models of C4-C6 were constructed and developed to simulate the situations of pre-subsidence and post-subsidence. The Taguchi method was used to obtain the optimal design parameters of the vertebral body cage to increase the subsidence resistance. The results showed that the optimum combination for a situation of pre-subsidence was gear ring, inner diameter of 4 mm, spike's height of 0.5 mm, twelve spikes, spike's oblique of 0⁰, spike's upper width of 0.3 mm, spike's upper length of 0.85 mm, and spike's lower area of 1.2 × 0.85 mm². For a situation of post-subsidence, the optimum combination was circular ring, inner diameter of 4 mm, spike's height of 2 mm, twelve spikes, spike's oblique of 0⁰, spike's upper width of 0.3 mm, spike's upper length of 0.85 mm and spike's lower area of 1.2 × 0.85 mm². Besides, subsidence is also affected by other variables including bone graft, bone mineral density, endplate preparation and implant material. Those variables were investigated and the results showed that the higher BMD, larger endplate preparation and less stiffness of implant material could reduce the risk of subsidence. The Taguchi method has an efficient reduction of time and cost of experiment and could determine the optimum combinations to enhance the ability to resist the subsidence.

A nonlinear rate dependent constitutive model for fiber-reinforced composites is presented. Through the use of a plastic potential function, effective stress and effective plastic strains are introduced, with which a single equation is established for the orthotropic and nonlinear rate dependent behavior of composites. This viscoplasticity constitutive model is employed together with a microbuckling model to predict compressive strength of composites for different strain rates. Results of qasi-static and high strain rate compression tests using off-axis composite specimens of S2/8552 glass/epoxy are reported and compared with model predictions. Excellent agreement between experimental data and predictions is found. From the experimental results as well as model predictions, it is noted that the longitudinal compressive strength of a composite is significantly influenced by the presence of shear stresses.

Experiments on the compressive strength and splitting tensile strength of desert sand high strength concrete with different fly ash dosage and desert sand replacement ratio were carried out. The regulation on the influence of fly ash dosage and desert sand replacement ratio on the compressive strength and splitting tensile strength of high strength desert sand concrete was analyzed. Experiment results show that with the increase of desert sand replacement ratio, the compressive strength and splitting tensile strength of high strength desert sand concrete increases first, followed by a decline. With the enhancement of fly ash dosage, the compressive strength and splitting tensile strength of high strength desert sand concrete also increases first, then declines, which provides guidance for the engineering application of desert sand.