Effects of Newly Developed Cellulose Oil Palm Fiber in the Fatigue Failure of Stone Mastic Asphalt

Fatigue or tensile cracking along wheel paths of vehicles are predominant on Malaysian roads as compared with other forms of distress. This is primarily due to accelerated loading from trucks, which is causing the authorities millions of ringgit on road maintenance alone. This situation is further aggravated with the traditional use of soft 80-100 penetration binders, which are poor in shear strength. At the same time, the use of additives such as Ethylene Vinyl Acetate (EVA) has proved costly. With the rising cost of asphalt in Malaysia, construction and rehabilitation of asphalt road pavements are expected to constrain the road agencies’ budget in the coming years. The objectives of this study were to research the rheological properties of newly developed cellulose oil palm fibers and their potential in resisting fatigue failure of Stone Mastic Asphalt (SMA). The research was undertaken in two parts. The first part of the study was carried out at UPM on SMA with granite aggregates. The selection of aggregate and asphalt for the study were done based on typical SMA mix requirements. Utmost importance was given to the use of the newly developed cellulose oil palm fiber in SMA. Out of the six types of cellulose fibers obtained through various types of pulping procedures, the Chemical Refined(Chem-R) Cellulose Fiber gave the best performance in terms of drain-down and rheological properties such as complex shear modulus. As such Chem-R cellulose fiber was selected and used throughout the study in proportions of 0.0%, 0.2%, 0.4%, 0.6%,0.8%,1.0% in 100mm cylindrical SMA14 mix design and fatigue and IDT tests. SMA specimens, prepared with the above cellulose fiber proportions were tested to simulated loading and temperature conditions in accordance with the American Standard for Testing and Materials (ASTM) and Association of American State Highway and Transportation Officials (AASHTO) Standards. The various proportions of cellulose oil palm fiber tested in 100 mm cylindrical specimens showed remarkable improvement in terms of fatigue life, stiffness and modulus. All of the SMA14 specimen properties increased as the fatigue life increased to a maximum value that corresponds to about 0.6% fiber. Remarkably, at 0.6% optimum fiber content, the initial strain decreased while the stiffness modulus increased, as compared with SMA14 specimens without fibers. The diameteral fatigue, and beam flexure tests have become popular in the Super Pave and AASHTO Tests. Along with that, new approaches in the fatigue analysis such as Dissipated Energy Ratio(DER), and Stiffness have also become very useful in the analysis of asphalt beams. Tests carried out on SMA9.5 beam specimens with the same cellulose fiber proportions as in SMA14, displayed similar trends in the fatigue performance of cellulose fibers regardless of the aggregate and gradation types. Maximum performance curves for fatigue life, stiffness and DER for the SMA9.5 beams were established. The fatigue life of beam specimens showed a maximum value between 0.6 and 0.8% of fiber contents, and the trend was similar for other parameters such as stiffness and DER. The results indicated that use of cellulose oil palm fibers greatly reduced the stiffness of the SMA9.5 and increased the number of load cycles to failure. These special characteristics of the fibers are expected to extend the life span of SMA pavement in the field. In addition, DER value was found to be the lowest for 0.6% cellulose oil palm fibers indicating a decreased loss of energy through dissipation. The more energy is retained and stored the longer life of the SMA pavements. Another important aspect observed in this study was the resistance of cellulose oil palm fibers to fatigue failure of SMA mixes. Several 150mm IDT samples were tested to determine the maximum indirect tensile stress, crack initiation, and propagation. The specimens tested in accordance with AASHTO TP-9 standard showed an increase in indirect tensile stress at 0.6% fiber proportions before taking a down turn. This seems to be promising for more new research in the area since previous research by others showed that gap graded mixes such as SMA displayed poor tensile strength. Two new approaches were undertaken to study the resistance of cellulose fibers against fatigue life of SMA. The first crack tensile stress and the maximum tensile stress values were used to quantify the fatigue resistance of the newly developed cellulose oil palm fibers. The fiber fatigue resistance quantifying approach is termed as Sustenance Ratio (SR). SR in this newly developed approach is defined as the ability of cellulose fibers to carry the maximum applied load to the first crack load divided by the time taken or total number cycles to failure. The unit of measure can be kN/sec or kN/cycles. Using this newfound analogy, the SR of various fiber percentages in SMA9.5 cylindrical specimens were determined. It was observed that the SR decreased to the lowest point at 0.6% fiber content, indicating a higher fatigue resistance. It was observed that the lower the SR the higher the fatigue resistance of fibers. In summary, it has been shown that the addition of Cellulose Oil Palm Fiber (COPF) up to 0.6% provides the maximum fatigue resistance to SMA which can be measured in terms of SR for various temperatures and load configuration. Another concept that was developed in this study was the Crack Meander (ξ) concept analogous to that of a river meander. Theoretically the lower the resistance encountered along the path of crack propagation, the more linear the line of crack becomes. The crack initiation and propagation within the 40mm gauged stress zone, was captured using a SLR camera, and the crack pattern was digitized. It was observed that the crack started to meander as the fiber proportions in the mix increased. A maximum meander was observed at a fiber content of 0.6%. The crack propagation within the stress zone appeared to be pinned by fiber reinforcements thus causing the line of crack to meander and propagate through weaker matrix

ANALYTICAL MODELING, TESTING, AND COMPARISON OF 1-D, 2-D, AND 3-D DEWATERING PROCESS

Geotextile tubes are used in dewatering applications over many decades for a variety of slurries, sediments, and wastes. With the increased use of geotextile tubes dewatering in recent years, the desire to maximize both the dewatering rate and retention lead to the use of chemical accelerant, which has become a standard practice in geotextile dewatering projects. A variety of small-scale, medium-scale, and pilot-scale test methods are used to assess geotextile tube dewatering performance, including Falling Head Test (FHT), Pressure Filtration Test (PFT), hanging bag test (HBT), Geotextile-tube Demonstration Test (GDT), and Pressure Gravity Dewatering Test (PGDT). However, a very few studies compare different types of dewatering tests and no proper correlations have been developed between test methods. The scope of this study is to (1) analyze dewatering process on radial and axial directions using a two-dimensional dewatering apparatus, which is basically a cylindrical geotextile tube, where the axial and radial flows are measured separately (2) analytical modelling of 1-D, 2-D, and 3-D dewatering process, and to (3) compare the results of analytical model and the experimental results of 1-D, 2-D, and 3-D dewatering test methods. In the process of comparing different test methods, the effect of multiple filling, final solids concentration, and turbidity of the effluent were considered. Three different tests (PFT, P2DT, and GDT), two different sediments under different solids concentrations and five different geotextiles, including woven, non-woven and geo-composites were used in this study. Relationship between radial filter cake height and flow ratio was (ratio between radial and axial flows of P2DT) observed. The dewatering parameters obtained using analytical modelling were compared between test methods. The analytical model proposed in this study can be used to predict the dewatering behavior under alternative conditions, including the changes in pumping rates, solids concentration of the slurry being pumped, geotextile tube sizes, number of dewatering cycles, dewatering duration, filling heights, final solids concentration of filter cake, and in cumulative volume of slurry. Analyzing the alternative dewatering scenarios using an analytical model prior to full-scale implementation, without conducting further dewatering performance tests, is a great benefit in terms of material time and money. This study lays out the framework to predict the dewatering behavior of full-scale tests using an analytical model generated from a lab tests, such as Pressurized 2-Dimensional Dewatering Test (P2DT). The limitations of this analytical model are that the analytical model does not account for the changes in the slurry properties other than the solids concentration and the changes in the overall pressure inside the geotextile tube. Alternative dewatering scenarios including changes in slurry and in pressure requires a performance test to be conducted to determine the dewatering parameters

Zolpidem, a clinical hypnotic that affects electronic transfer, alters synaptic activity through potential GABA receptors in the nervous system without significant free radical generation

Zolpidem (trade name Ambien) has attracted much interest as a sleep-inducing agent and also in research. Attention has been centered mainly on receptor binding and electrochemistry in the central nervous system which are briefly addressed herein. A novel integrated approach to mode of action is presented. The pathways to be discussed involve basicity, reduction potential, electrostatics, cell signaling, GABA receptor binding, electron transfer (ET), pharmacodynamics, structure activity relationships (SAR) and side effects. The highly conjugated pyridinium salt formed by protonation of the amidine moiety is proposed to be the active form acting as an ET agent. Extrapolation of reduction potentials for related compounds supports the premise that zolpidem may act as an ET species in vivo. From recent literature reports, electrostatics is believed to play a significant role in drug action

Novel, unifying mechanism for mescaline in the central nervous system: Electrochemistry, catechol redox metabolite, receptor, cell signaling and structure activity relationships

A unifying mechanism for abused drugs has been proposed previously from the standpoint of electron transfer. Mescaline can be accommodated within the theoretical framework based on redox cycling by the catechol metabolite with its quinone counterpart. Electron transfer may play a role in electrical effects involving the nervous system in the brain. This approach is in accord with structure activity relationships involving mescaline, abused drugs, catecholamines and etoposide. Inefficient demethylation is in keeping with the various drug properties, such as requirement for high dosage and slow acting

From Internet of Things to Internet of Data Apps

We introduce the Internet of Data Apps (IoDA), representing the next natural progression of the Internet, Big Data, AI, and the Internet of Things. Despite advancements in these fields, the full potential of universal data access - the capability to seamlessly consume and contribute data via data applications - remains stifled by organizational and technological silos. To address these constraints, we propose the designs of an IoDA layer borrowing inspirations from the standard Internet protocols. This layer facilitates the interconnection of data applications across different devices and domains. This short paper serves as an invitation to dialogue over this proposal.Comment: 5 pages, 2 figure

quantification of coarse aggregate angularity by a newly developed auto grader machine

The physical properties of aggregates have a direct correlation to the performance of a pavement. Stiffness, fatigue response, shear resistance and permanent deformation are some of the distresses for which aggregate form, texture and angularity have an influence. Angularity is an important property of aggregate shape, more angular are the particles there will be better interlocking, inter friction and greater mechanical stability, hence better pavement distress resistance. A debate has a risen over several methods to capture this physical property either directly or indirectly such as aggregate imaging system (AIMS), Un compacted void content of coarse aggregate (AASHTO T326), University of Illinois Aggregate Image Analyzer (UIAIA) and Indian manual coarse aggregate angularity test. Some are costly some are laborious and time consuming; hence there is a need for better methods that are cost effective, accurate, rapid in measuring aggregate angularity. The research conducted in this study introduces cost effective Aggregate Auto-grader and evaluates the effective set of time and speed for this automated machine to obtain minimum percentage air voids between aggregates (estimation of perfect interlocking) by shaking sample of coarse aggregates in orbital motion. In addition to measure accuracy of automate Aggregate Auto-grader test results are compared to other manual coarse aggregate angularity test. The trend followed by results of aggregate Auto-grader is as same as the manual test, hence based on results a new equation is proposed for obtaining coarse aggregate angularity by Aggregate Auto-grade machine which has more accuracy, reputability and reproducibility compare to the manual test