For sustainable pavement construction, this research paper aims to investigate the feasibility of using Waste Cooking Oil (WCO) and Waste Engine Oil (WEO) as rejuvenators on the rheological properties of aged bitumen extracted from Reclaimed Asphalt Pavement (RAP). The aged bitumen was extracted from milled RAP recruited from an old pavement. The rheological characteristics of the rejuvenated bitumen were determined by penetration, softening point, Brookfield viscosity, Dynamic Shear Rheometer (DSR), and Bending Beam Rheometer (BBR) tests. In addition, the chemical composition of virgin (control), aged and rejuvenated bitumen by WCO, and WEO was investigated using Fourier Transform Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray (EDX). The quality of the rejuvenated bitumen was also evaluated by the Scanning Electron Microscopy (SEM) imaging technique. Based on penetration and softening point testing results, the optimum percentages of the waste oils were found to range from 3.5 to 4.0% for the WCO and from 5.5 to 6.0% for the WEO. The aged bitumen properties were significantly improved by rejuvenators as evidenced by the chemical analysis (FTIR and SEM/EDX) along with the ratio of asphaltenes to maltenes. Furthermore, the surface morphology was renovated as well as the fundamental physical properties of the rejuvenated aged bitumen. Additionally, the rejuvenated bitumen showed less tendency to short-term aging as confirmed by the DSR results. BBR results of rejuvenated aged bitumen samples exhibited comparable performance to those of the control samples at different low temperatures having a performance grade of PG 64-28. Moreover, rejuvenated 100% RAP mixes were found to cope with Egyptian requirements for heavy traffic as binder courses and medium traffic as wearing courses in terms of Marshall stability and flow. Finally, Indirect Tensile Strength (ITS) results were within the specification limits.

Introduction

Despite the limited resources, about 110 million tons of bitumen are used annually in the highway industry worldwide [1]. Bitumen is an organic hydrocarbon material with high thermal sensitivity. Exposure to elevated temperatures during mixing and placement of the Hot Mix Asphalt (HMA), and the environmental conditions throughout the pavement service life, lead to aging of the asphalt binder. The loss of volatiles and oxidation of bitumen (as bitumen is a hydrocarbon material) are the main causes of aging, which result in higher viscosity and stiffer bitumen [2]. Aged bitumen tends to lose its flexibility and turns into a brittle material that is prone to crack easily [3]. There has been an enormous increase in the use of Reclaimed Asphalt Pavement (RAP) worldwide as an economic and environmentally sound alternative for sustainable pavement construction [4–6]. However, some road authorities are hesitant in encouraging the use of RAP in pavement construction on a large scale due to some limitations. The barriers that limit the use of high RAP percentages (more than 15%) are the high variability in milling processes, mixing RAP from different sources, different properties of aged bitumen than required for virgin bitumen, in addition to one more additional material to care about during HMA manufacturing [6,7].

The influence of polymeric structure of polycarboxylate-ether (PCE) based superplasticizers on the intercalation behavior in sodium montmorillonite clay (Na-MNT) is investigated by performing in-situ X-ray diffraction (XRPD) on fresh, unaltered clay pastes. The use of this technique reveals the real influence of the PCE structure and of the PCE/clay dosage ratio on the expansion profile of the clay. This is not observed with the traditional XRPD methodology performed on dried clay pastes, which shows the same values of d-spacing despite using polymers of diverse structures. It is observed that PCE polymers with long side chains and high side chain density result in larger expansion. Additionally, polymers with a high anionic charge saturate the interlaminar space of montmorillonite at a lower dosage. The experimental results also indicate that clay exfoliation is critical in the intercalation process and the exfoliation tendency of the clay is influenced by the structure of PCE polymers.

Introduction

The dispersing capacity and water reduction efficiency of polycarboxylate-ether (PCE) based superplasticizers is severally affected by the presence of montmorillonite clays (MNT) in the sands used for concrete production. This type of clays has the ability to absorb large quantities of PCE polymers through an intercalation mechanism of the PEG/PEO (poly-ethylene glycol/polyethylene oxide) side chains of the polymer [1,2], which is responsible for the partial or total loss of their dispersing capacity. The absorption behaviour of PCE-based superplasticizers on MNT clay has already been investigated by different authors using XRPD analysis on centrifuged and dried clay pastes [1,2]. These studies show almost no influence on the d-spacing of MNT clay when different structures of PCE polymers are used since the maximum clay expansion value always remains in the range of 18–21 Å and, in all cases, the average differences of d001 values within PCE polymers of diverse structures does not exceed 3 Å (the distance equivalent to one water molecule arranged in the interlayer of MNT clays).

Assessing the success of sensor-based sorting in the raw materials industry currently requires timeconsuming and expensive empirical test work. In this contribution we illustrate the prospects of successful sensor selection based on data acquired by scanning electron microscopy-based image analysis. Quantitative mineralogical and textural data from more than 100 thin sections were taken to capture mineralogical and textural variability of two different ore types from the H€ ammerlein SneIneZn deposit, Germany. Parameters such as mineral grain sizes distribution, modal mineralogy, mineral area and mineral density distribution were used to simulate the prospects of sensor-based sorting using different sensors. The results illustrate that the abundance of rock-forming chlorite and/or density anomalies may well be used as proxies for the abundance of cassiterite, the main ore mineral. This suggests that sorting of the Hammerlein ore may well be achieved by either using a short-wavelength infrared detector € d to quantify the abundance of chlorite d or a dual-energy X-ray transmission detector to determine the abundance of cassiterite. Empirical tests conducted using commercially available short-wave infrared and dual-energy X-ray transmission sensor systems are in excellent agreement with simulation-based predictions and confirm the potential of the novel approach introduced here.

Introduction

Sensor-based sorting is a technology applied by the mining industry to reject coarse barren particles (in a size range between 10 and 100 mm) of a heterogeneous ore at an early stage of a beneficiation process (Knapp et al., 2014; Wills and Finch, 2016; Wotruba and Harbeck, 2010). The sorting process can be subdivided into four basic steps, as illustrated in Fig. 1 by the example of a chute sorter (Nienhaus et al., 2014). Before sensor-based sorting can be implemented into a flow sheet it must be the first objective to identify the sensor, which is able to detect d or even quantify d a suitable property that allows classifying the particles of the investigated ore type into concentrate and waste. Most commonly, direct identification of the mineral of interest is not possible because suitable sensors are not available. In such cases, a measureable property that correlates well with the mineral/element of interest d a so-called proxy d can be selected for sensor-based sorting. Examples of commonly-detected properties/proxies are atomic density with a (dual-energy) X-ray transmission sensor, (DE-)XRT for short (e.g. Neubert and Wotruba (2016); Robben et al. (2013); Walker (2017)), color, fluorescence, or transparency (optical sensor), shortwavelength infrared or near-infrared radiation (SWIR/NIR; e.g. Dalm et al. (2017); Phiri et al. (2018); Iyakwari et al. (2013)), or X-ray fluorescence (XRF; e.g. Nadolski et al. (2018)).

In this paper sound absorption characteristics of silica aerogel/polyester (PET) blankets are investigated. PET fibers were made on an industrial scale compact melt spinning line and then processed on a laboratory scale needling line to produce nonwoven fabrics. The silica aerogel blankets were prepared by in situ synthesis of silica aerogel on the nonwoven fabrics via a two-step sol-gel process of tetraethoxysilane which was followed by drying at ambient pressure. In order to achieve aerogel particles with different pore structure and properties, various synthesis conditions were used. The nonwoven samples were characterized in terms of thickness, fiber diameter, porosity and pore size by X-ray micro-computed tomography and scanning electron microscopy. Moreover, nitrogen adsorption analysis was carried out to determine the specific surface area and pore structure of aerogel particles. The effect of pore structure, physical properties and hydrophobicity of aerogel particles on sound absorption coefficient (SAC) of blankets was investigated using two-microphone transfer function method. Also, the effect of sol volume and nonwoven thickness was investigated. The results indicated that at all frequency levels, silica aerogel/PET blankets enjoy higher SAC than their untreated counterparts. It was found that, SAC is strongly affected by the pore structure of aerogel particles. Silica aerogels with lower bulk densities, larger pore size and higher porosities exhibited better sound absorption performance. The results also indicated that hydrophobic aerogel blankets exhibit higher SAC as compared with hydrophilic blankets. The results also showed that the thickness of nonwoven fabric strongly affects the SAC of aerogel blankets.

Introduction

In recent decade, noise pollution has become the most widespread and least controlled environmental issue. Noise pollution causes or contributes to not only psychological disorders, but also cardiovascular disease, loss of hearing, high blood pressure and tinnitus hearing impairment. Thus technological control of acoustical behavior of industrial products is a fact that has to be scientifically faced by researchers [1]. This control can be achieved using either sound insulating or sound absorbing materials. Conventional various sound absorbers such as foam-like materials or nonwoven fabrics as low-density porous materials can prevent reflection of the incident sound waves and hence increase sound absorption. The use of nonwovens, as widely accepted porous sound absorbing materials, has been extensively researched [2–6]. Since more than a decade, acoustic engineers have been looking for lightweight sound absorbing materials in buildings. The challenge primarily stemmed from inability of conventional bulky nonwoven fabrics and foams to absorb sound waves, specifically sound waves of low frequency bands that impair speech comprehension [7,8].

1. Introduction

2. Methods

3. Results and Discussion

4. Conclusions and Outlook

Acknowledgments

References

In casting, molding, or additive manufacturing processes, there are some typical issues that can change the geometry of a part and cause porosity or other defects. With the aid of X-ray computed tomography (CT), internal discontinuities and geometry deviations can be accurately detected and visualized. However, the question remains in how far a given defect affects mechanical failure. We aim at bridging this gap by structural mechanics simulations based on CT images. In this study, we describe a method to predict the tensile strength and the location of crack initiation from the simulated stress distributions on the basis of local stress concentrations. We validate the method for tensile rods and real-life aeronautic parts which were additively manufactured from an AlSi10Mg aluminum alloy. Thirty-six specimens were manufactured in total, where different porosity patterns were deliberately inserted. The specimens were CT-scanned in high resolution. Structural mechanics simulations were carried out on basis of the CT images. An immersed-boundary finite elements code is used. The generation of a conforming simulation mesh is not required, making the code suitable especially for complex geometries like porous objects. The same test specimens were subjected to destructive physical tensile tests. We show that there is a very good correlation between the predicted and measured tensile strengths, and that the location of the first crack occurrence can be forecasted accurately.

Introduction

Structural parts almost inevitably differ from their ideal geometry due to the manufacturing process. In casting and injection moulding, gas or shrinkage pores are common kinds of defects. In additive manufacturing by sintering or melting, heat variations can cause imperfect bonding of the material granules. Industrial X-ray computed tomography (CT) allows for the non-destructive detection and visualization of many kinds of superficial or internal defects. With today’s CT scanners reaching spatial resolutions down to the micrometer scale, a CT image constitutes an accurate three dimensional digital representation of the scanned part. The spatial distribution and the morphological features of the porosity can thus be assessed in detail [1, 2]. However, the mere presence of porosity does not necessarily render a part unusable. In fact even highly porous parts can still be good for a specific purpose. In order to minimize false rejections and thus production costs it is desirable to assess the “effect of the defect”, i.e., to what degree a geometric defect affects the mechanical function. Work has been done to relate the detected porosity to fatigue behavior in aluminum castings [3] and laser-melted parts [4], sometimes combining the pore geometry with heuristic modeling of the pore physics [5, 6] or with analyzing stress concentrations at individual pores using finite element analysis [7].

1- Introduction

2- Data and calculations

3- Results and conclusions

References

Abstract

The Spectrometer Telescope for Imaging X-rays (STIX) is one of the instruments installed onboard Solar Orbiter mission which will be launched in February 2020. After 1.5 years of cruise phase it will start to gather scientific data from the orbit with perihelion distance about 0.28 au. It means that STIX will operate also during the next solar minimum. In the paper we estimate flux measured by the instrument during periods of low solar activity. For this purpose we used solar observations which were recorded by the Solar Photometer in X-rays (SphinX) during the last minimum of solar activity. The estimation was obtained for instruments overlapping energy range from 4 to 15 keV. Presented results indicate that STIX instrument will provide efficient imaging the solar emission even during low level of solar activity (B1 GOES class).

Introduction

Solar Orbiter (Müller et al., 2013), a European Space Agency’s mission, will be launched with an Atlas V rocket from the Cape Canaveral in Florida in February 2020. Following launch, Solar Orbiter will begin its 1.5 year journey to the Sun. In order to reach its near-Sun orbit, the spacecraft with use a series of gravity assists from Venus and the Earth, in essence, using them to catapult itself towards the Sun. The Spectrometer/Telescope for Imaging X-rays (STIX: (Krucker et al., 2016)) is one of the 10 instruments that are part of the scientific payload for the Solar Orbiter mission. STIX will provide imaging spectroscopy of thermal and non-thermal solar X-ray emission from 4 to 150 keV. It applies a Fourier-imaging technique using a set of tungsten grids in front of 30 pixelated CdTe detectors. Although STIX instrument is design to observe flares events, we decided to estimate flux measured by the instrument during period of low solar activity. For this purpose we used solar observations which were recorded by the Solar Photometer in X-rays (SphinX: (Sylwester et al., 2008; Gburek et al., 2013; Gryciuk et al., 2017)), instrument designed to observe soft X-ray (SXR) solar emission in the energy range between 1 keV and 15 keV with the resolution better than 0.5 keV. The SphinX operated from February until November 2009 aboard CORONAS-Photon satellite, during the phase of exceptionally low minimum of solar activity.