Microstructural Characteristics of Interfacial Zone in Asphalt Mixture Considering the Influence of Aggregates Properties

The interfacial zone between aggregate particles and asphalt mortar presents a significant effect on the strength of an asphalt mixture. In this paper, basalt, limestone, and diabase were selected, and the influence of these aggregates on the mechanical characteristics and microstructures of the interfacial zone was investigated. Nanoindentation was employed to measure the change law of mechanical behavior in the region of the interfacial zone, and corresponding viscoelastic parameters were deduced; microstructural morphology was observed by scanning electron microscopy, and the effect of the mineralogical components on the interfacial zone was analyzed as well. Results show that the mechanical behavior of the interfacial transition zone is complicated. The modulus and hardness of asphalt mortar decrease with the increases in the aggregate surface distance, and then keep stable after the distance is greater than 40 μm. Both the relaxation time and dissipated energy ratio of the interfacial zone affected by the different aggregate types show a similar change law. These states indicate that aggregate types have little influence on the stress dissipation of asphalt mortar. However, creep compliances that quantify the ability of the deformation resistance show a significant difference; microstructure morphologies of the interfacial zone are affected by aggregates obviously, and micro pores present a different distribution and state in the interfacial zone.

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Evaluating Micro-Structure, Hydration and Thermal Expansions of Cement Containing Nano-Silica

GIS Business ◽

10.26643/gis.v15i1.18226 ◽

2020 ◽

Vol 15 (1) ◽

pp. 158-165 ◽

Cited By ~ 1

Author(s):

Dr. Sarvesh PS Rajput

Keyword(s):

Portland Cement ◽

Mechanical Characteristics ◽

Microstructural Properties ◽

Nano Silica ◽

Micro Structure ◽

Microstructural Characteristics ◽

Mechanical And Microstructural Properties

This study reported that the addition of nano-silica enhances the mechanical characteristics of concrete as its compressive, flexural and tensile split strengths are increased. As a comparison mixture to equate it along with nano-modified concrete, ordinary samples of Portland cement (OPC) have been utilized. Herein, upto 6.0 percent of OPC has been substituted by nanosilica. In fact, the introduction of nanosilica improves mechanical and microstructural characteristics of concrete by significantly (28 to 35%). The finding therefore, indicated that partly replacing OPC with up to 5 percent nanosilica increases the mechanical and microstructural properties cured up to ninety days as opposed to the standard OPC mix.

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Microstructural characteristics and mechanical behavior of microwave-assisted sintered ferromagnetic FeCoNi1.5CrCu HEAp/Al matrix composites

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2020.158439 ◽

2021 ◽

Vol 861 ◽

pp. 158439

Author(s):

Li Guirong ◽

Wen Haoran ◽

Wang Hongming ◽

Ren Wenxiang ◽

Yan Yuwei ◽

...

Keyword(s):

Mechanical Behavior ◽

Matrix Composites ◽

Microstructural Characteristics ◽

Microwave Assisted ◽

Al Matrix Composites ◽

Al Matrix

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Mechanical Behavior for some Cobalt Alloys

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1114.9 ◽

2015 ◽

Vol 1114 ◽

pp. 9-12

Author(s):

Alexandru Ghiban ◽

Brandusa Ghiban ◽

Cristina Maria Borţun ◽

Nicolae Serban ◽

Mihai Buzatu

Keyword(s):

Tensile Strength ◽

Chemical Composition ◽

Mechanical Behavior ◽

Mechanical Characteristics ◽

Fractographic Analysis ◽

Cobalt Alloys ◽

Dental Alloys ◽

Bending Tests ◽

Longitudinal Modulus

Four compositions of some usually commercial dental alloys were investigated in order to determine the mechanical characteristics and fractographic analysis of tensile and bending tests surfaces. A correlation between chemical composition (either molybdenum or molybdenum and chromium contents) and mechanical characteristics (longitudinal modulus, tensile strength and elongation) were finally done.

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Analysis of the Crack Fracture Morphology of the Asphalt Mixture under Tensile Stress Effects

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.250-253.3533 ◽

2011 ◽

Vol 250-253 ◽

pp. 3533-3537 ◽

Cited By ~ 1

Author(s):

Li Hua Zhao ◽

Jing Yun Chen ◽

Sheng Wu Wang

Keyword(s):

Brittle Fracture ◽

Fracture Surface ◽

Tensile Stress ◽

Mechanical Characteristics ◽

Asphalt Mixture ◽

Fracture Morphology ◽

Microscopic Mechanism ◽

Interface Zone ◽

Stress Effects ◽

Bending Fracture

Through studying the bending fracture and cleavage fracture of the asphalt mixture within the different temperature condition, confirming that the temperature influences the microscopic mechanism of mixture cracking: the fracture is relatively flat with low temperture, the destruction of the asphalt mixture is also mainly result of the brittle fracture; As the temperature rise, fracture surface becomes coarse, some part show large plastic elapse deformation. Adding fiber can reduce thickness of the asphalt membrane, improve the bonding strength of asphalt mastic, and greatly increase the ratio of the aggregate fracture and interface zone fracture, so as to enhance the asphalt mixture crack-resistance. The fracture morphology of asphalt mixture has a better reflection for its mechanical characteristics.

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COMPARISON OF RECENTLY USED PHACOEMULSIFICATION SYSTEMS USING A HEALTH TECHNOLOGY ASSESSMENT METHOD

International Journal of Technology Assessment in Health Care ◽

10.1017/s0266462317000472 ◽

2017 ◽

Vol 33 (2) ◽

pp. 232-238

Author(s):

Jiannan Huang ◽

Qi Wang ◽

Caimin Zhao ◽

Xiaohua Ying ◽

Haidong Zou

Keyword(s):

Health Technology Assessment ◽

Technology Assessment ◽

Vision System ◽

Health Technology ◽

Assessment Method ◽

Dissipated Energy ◽

Positive Trend ◽

Significant Difference ◽

Tertiary Hospitals ◽

Cataract Patients

Objectives: To compare the recently used phacoemulsification systems using a health technology assessment (HTA) model.Methods: A self-administered questionnaire, which included questions to gauge on the opinions of the recently used phacoemulsification systems, was distributed to the chief cataract surgeons in the departments of ophthalmology of eighteen tertiary hospitals in Shanghai, China. A series of senile cataract patients undergoing phacoemulsification surgery were enrolled in the study. The surgical results and the average costs related to their surgeries were all recorded and compared for the recently used phacoemulsification systems.Results: The four phacoemulsification systems currently used in Shanghai are the Infiniti Vision, Centurion Vision, WhiteStar Signature, and Stellaris Vision Enhancement systems. All of the doctors confirmed that the systems they used would help cataract patients recover vision. A total of 150 cataract patients who underwent phacoemulsification surgery were enrolled in the present study. A significant difference was found among the four groups in cumulative dissipated energy, with the lowest value found in the Centurion group. No serious complications were observed and a positive trend in visual acuity was found in all four groups after cataract surgery. The highest total cost of surgery was associated with procedures conducted using the Centurion Vision system, and significant differences between systems were mainly because of the cost of the consumables used in the different surgeries.Conclusions: This HTA comparison of four recently used phacoemulsification systems found that each of system offers a satisfactory vision recovery outcome, but differs in surgical efficacy and costs.

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Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures

Materials ◽

10.3390/ma14227060 ◽

2021 ◽

Vol 14 (22) ◽

pp. 7060

Author(s):

Mohammad Alharthai ◽

Qing Lu ◽

Ahmed Elnihum ◽

Asad Elmagarhe

Keyword(s):

Tensile Strength ◽

Asphalt Mixture ◽

Asphalt Mixtures ◽

Indirect Tensile Strength ◽

Laboratory Evaluation ◽

Void Content ◽

Coarse Aggregates ◽

Significant Difference ◽

Indirect Tensile ◽

Marshall Stability

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

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Efficiency of Bio-Sourced Composites in Confining Recycled Aggregates Concrete

10.4028/www.scientific.net/cta.1.505 ◽

2022 ◽

Author(s):

Elhem Ghorbel ◽

Mariem Limaiem

Keyword(s):

Mechanical Behavior ◽

Analytical Modeling ◽

Mechanical Characteristics ◽

Epoxy Polymer ◽

Experimental Results ◽

Confined Concrete ◽

Recycled Aggregates ◽

Demolition Waste ◽

Traditional System ◽

Flax Fibers

This research investigates the efficiency of using Flax Fibers reinforced bio-sourced polymer by comparison to traditional system based on Carbone Fiber Reinforced Epoxy Polymer in order to confine recycled aggregates concrete. Four concrete formulations have been formulated by incorporating recycled aggregates from demolition waste (0%, 30%, 50% and 100%). An air-entraining agent was added to the formulations to achieve the level of 4% occluded air. The main objective is to discuss and to evaluate the effectiveness of confining them using bio-sourced composite by comparison to traditional ones. To hit this target, the developed approaches are both experimental and analytical. The first part is experimental and aimed to characterize the mechanical behavior of the materials: the composites used in the confining process the unconfined concrete (effect of incorporating recycled aggregates on the overall mechanical characteristics). We establish that bio-sourced composites are efficient in strengthening recycled aggregates concrete especially if they are air-entrained. The second part of this work is dedicated to analytical modeling of mechanical behavior of confined concrete with composite under compression based on Mander’s model. The input parameters of the model were modified to consider the rate of recycled aggregates incorporation. Comparison between experimental results and the modified Mandel’s Model is satisfactory.

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Viscoelastic Parameters of Asphalt Mixtures Identified in Static and Dynamic Tests

Materials ◽

10.3390/ma12132084 ◽

2019 ◽

Vol 12 (13) ◽

pp. 2084 ◽

Cited By ~ 1

Author(s):

Piotr Mackiewicz ◽

Antoni Szydło

Keyword(s):

Permanent Deformation ◽

Asphalt Mixture ◽

Dynamic Test ◽

Asphalt Mixtures ◽

Rheological Parameters ◽

Dynamic Tests ◽

Static Test ◽

Viscoelastic Parameters ◽

Static Creep ◽

Asphalt Content

We present two methods used in the identification of viscoelastic parameters of asphalt mixtures used in pavements. The static creep test and the dynamic test, with a frequency of 10 Hz, were carried out based on the four-point bending beam (4BP). In the method identifying viscoelastic parameters for the Brugers’ model, we included the course of a creeping curve (for static creep) and fatigue hysteresis (for dynamic test). It was shown that these parameters depend significantly on the load time, method used, and temperature and asphalt content. A similar variation of parameters depending on temperature was found for the two tests, but different absolute values were obtained. Additionally, the share of viscous deformations in relation to total deformations is presented, on the basis of back calculations and finite element methods. We obtained a significant contribution of viscous deformations (about 93% for the static test and 25% for the dynamic test) for the temperature 25 °C. The received rheological parameters from both methods appeared to be sensitive to a change in asphalt content, which means that these methods can be used to design an optimal asphalt mixture composition—e.g., due to the permanent deformation of pavement. We also found that the parameters should be determined using the creep curve for the static analyses with persistent load, whereas in the case of the dynamic studies, the hysteresis is more appropriate. The 4BP static creep and dynamic tests are sufficient methods for determining the rheological parameters for materials designed for flexible pavements. In the 4BP dynamic test, we determined relationships between damping and viscosity coefficients, showing material variability depending on the test temperature.

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Evaluation of Mechanical Behavior and Microstructural Characteristics of Photocatalytic Concretes to Be Used as Pavement Blocks

Journal of Engineering Materials and Technology ◽

10.1115/1.4033275 ◽

2016 ◽

Vol 138 (3) ◽

Author(s):

João Victor Staub de Melo ◽

Glicério Trichês

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Mechanical Behavior ◽

Tio2 Nanoparticles ◽

Modulus Of Elasticity ◽

Microstructural Characteristics ◽

State Tests ◽

Fresh State ◽

Hardened State ◽

Microstructural Behavior

This paper reports the results obtained in a study on the effect of the addition of TiO2 nanoparticles on the mechanical properties and microstructural characteristics of photocatalytic concretes. In the hardened state, tests to determine the compressive strength and modulus of elasticity were carried out. Also, microstructural aspects of the samples were investigated. In the fresh state, the influence of the addition of TiO2 on the concrete compaction and conduction calorimetry curves was evaluated. The results obtained indicated a better mechanical and microstructural behavior of concrete with addition of TiO2.

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