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

Experimental study of high temperature properties and rheological behavior of ceramic modified asphalt

Industry and by-product waste materials are commonly used in road construction. Ceramic is a class of inorganic, nonmetallic materials produced by the action of heat and subsequent cooling. This product is used widely around the world. The main objective of this study was intended to successfully implement crushed Ceramic Waste Dust (CWD) as a modifier to 80/100 penetration grade asphalt binder to investigate their potential end usage. The CWD powder percentages blended with base asphalt binder was 10% by weight of aggregate at asphalt to dust mass ratio of 1:1.60 was utilized and added into asphalt binder. Two different blends including control limestone dust were subjected to binder testing and grading using Superpave testing equipment and procedures. The microstructure composition, shape and size of particles of ceramic waste and limestone dust and the homogeneity of modified asphalt were analyzed by Energy dispersion analysis of x-ray (SEM-EDAX), Scanning Electron Microscope (SEM), and Environmental Scanning Electromicroscopy (ESEM) techniques respectively and other properties related to mineral filler in the asphalt mixture were also tested. Dynamic Shear Rheometer (DSR) was used to c and dynamic creep tests upon Limestone Dust (LSD), CWD modified and base asphalt binder samples. Morphology tests showed the pH of the ceramic was alkaline and hydrophobic. Thus, it can be potentially used as an anti-stripping additive in the asphalt mixture. The introduction of CWD resulted in reduced penetration, increased softening point, increased binder high temperature viscosity, and escalating the required mixing and compaction temperatures. The viscoelasticity test showed that ceramic waste dust improved the stiffness and the elastic portion of asphalt binder and the complex shear modulus in the high temperature domain. The performance grade (PG) of CWD modified asphalt is 4 grades higher than base asphalt binder and 2 grades higher than mastic containing limestone dust. Thus, it indicates that CWD may have a positive effect on high-temperature properties. The creep test results of the CWD modified asphalt show that the total strain and the permanent strain of asphalt mastics load-unload cycle can be significantly reduced, which results in the improvement of resistance to permanent deformation

An overview of conventional and surface free energy methods used to determine asphalt aggregate adhesion

Asphalt aggregate adhesion strength is the fundamental property that determines the moisture damage of asphalt pavement. Moisture damage is related to loss of stiffness or strength as a result of cohesive and adhesive failure of the pavement material. The conventional test for asphalt aggregate adhesion is only comparative and does not provide a quantitative value. Currently research is being carried out to introduce surface free energy measurements as fundamental means to quantify asphalt aggregate adhesion and cohesion. Some of the methods developed to measure surface free energy are Sessile Drop Method, Wilhelmy Plate Method, Adsorption Method, Inverse Gas Chromatography, and Micro-calorimeter. This could eventually lead to the development of a cost effective, accurate and reliable surface free energy measurement instrument which can be used by field engineers

Effect of 20 micron filler particle size and filler type on rheological and performance properties of stone mastic asphalt-filler mastics

This paper evaluates the relative performance of a series of 20 micron filler particle size and filler type asphalt-filler mastics in terms of the two main distress modes associated with flexible asphalt pavements of permanent deformation and fatigue damage. The study makes use of the fundamental rheological binder testing using a dynamic shear rheometer (DSR), pavement performance prediction by means of the Superpave binder parameters, dynamic creep, temperature steps, and time sweep tests. The fundamental rheological data at given filler/asphalt ratio together with the permanent deformation and fatigue testing in the DSR all indicate an improved rutting and fatigue performance for the coarse (greater than 75 micron) asphalt-filler mastics compared to the fine (less than 20 micron) asphalt-filler mastics regardless filler type. In terms of filler type, ceramic waste filler found to be more effective on producing mastics that are more elastic and less susceptible to rutting and cracking than the control mastic

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

An initial investigation of the use of local industrial wastes and by-products as mineral fillers in stone mastic asphalt pavements

Environmental awareness of the drawbacks of landfill sites is forcing nations to look for better ways to recycle and Increase usage of industrial wastes and by-products will both decrease the demand for available materials and help solve many disposal problems. The use of industrial wastes and by-products as Mineral fillers in asphalt mixtures is not a new technique. Mineral Fillers have been used in road construction for many years. They are incorporated in asphalt mixtures to enhance the properties and performance of asphalt concrete pavements. Mineral fillers vary in mineralogy, chemical properties, shape and texture, size, and gradation. The major objective of this initial investigation was to find out whether it is possible to use the local industrial and by-products wastes such as Steel slag, Ceramic waste, Coal fly ash, limestone, and Rejected ceramic raw material as mineral fillers in Stone Mastic Asphalt (SMA) mixtures in Malaysia. Chemical analysis using Scanning Electro Microscope (SEM), Energy Dispersive X-ray (EDX) and physical tests were performed on those local industrial and by-products wastes specimens to determine its chemical composition, size and shape of particles, as well as gradation and specific gravity, and were compared to limestone dust the common type of mineral filler used in Stone Mastic Asphalt in Malaysia. The test results indicate that the physical and chemical properties of the local industrial wastes are within specified limits of quality requirements for mineral filler for Bituminous Paving Mixtures AASHTO M17, and in accordance with AASHTO PP41 (Designing of Stone Matrix Asphalt) and these waste materials can potentially be used as mineral fillers in Stone Mastic Asphalt (SMA) Mixtures