Nur Izzi Md. Yusoff

Steel Slag as an Aggregate Replacement in Malaysian Hot Mix Asphalt

As natural aggregate sources are becoming depleted due to high demand in road construction and the amount of disposed waste material keeps increasing, researchers are exploring the use of alternative materials which could preserve natural sources and save the environment. In this study, steel slag was used as an aggregate replacement in conventional dense graded asphalt mixes (ACW14 and ACB28). Steel slag was selected due to its characteristics, which are almost similar to conventional aggregates, and the fact that it is easily obtainable as a by-product of the steel industry. The same gradations of mixtures were produced using normal crushed aggregate as control samples. The Marshall mix design system was used for sample preparation in accordance with Malaysian specifications. Samples of asphaltic concrete were subjected to the resilient modulus test, creep test and rutting test. Samples made from steel slag show significantly better results than conventional aggregate. Therefore, utilization of steel slag will reduce land fill, save natural resources and improve the strength of pavement to sustain a higher volume of vehicles. This will shift the gear in sustainable pavement construction, which is most desirable in today’s energy deficient world.

Performance evaluation of Al2O3 nanoparticle-modified asphalt binder

The rheological and physical properties of asphalt binders modified with aluminium oxide (Al2O3) nanoparticles were investigated. Al2O3 nanoparticles were added to the base asphalt binder at concentrations of 3, 5, and 7 wt.%. Superpave binder tests were conducted to evaluate the characteristics of the nano-Al2O3-modified binders. Rotational viscosity tests and a dynamic shear rheometer were used to analyse the rheological and physical properties of the modified binders, and Fourier transform infrared spectroscopy technique to observe changes in the structure of modified binders compared to the original. The penetration and ductility values decreased with added Al2O3 as well as temperature susceptibility. The phase angle δ is reduced with 5 wt.% or less Al2O3 added to the binder. The complex shear modulus G* significantly increased with the addition of up to 5 wt.% Al2O3. Results recognise 5 wt.% as the optimum level. The performance of nano-Al2O3-modified binders was enhanced regarding their resistance to both thermal rutting at high temperatures and fatigue cracking at low temperatures. Furthermore, statistical analysis of penetration, softening point, complex shear modulus, and phase angle results, using both one- and two-way ANOVA tests, show a significant difference level, having remarkable impacts on the dependent variables.

The Combination of a Fuzzy Analytical Hierarchy Process and the Taguchi Method to Evaluate the Malaysian Users’ Willingness to Pay for Public Transportation

This study is an attempt to overcome the lack of reliable estimates on the willingness of Malaysian users to pay for public transportation (particularly buses) through a combined analysis of a fuzzy analytical hierarchy process (F-AHP) and the Taguchi method. This is a ground-breaking study in the attempt to evaluate the bus users’ satisfaction factors based on the F-AHP, and find the pattern for the users’ willingness to pay (WTP) characteristic by reducing the travel time with the Taguchi application. The data were collected from the public transportation users’ intentions in Kelang Valley, Kuala Lumpur, Malaysia. The results convinced us that, for complex data, one requires flexible approaches that can adjust their combination methods to the properties of analyzed datasets. This study is interested in initiating the use of a system combination strategy to have a better understanding of the factors that motivate the public transportation users to be willing to pay for the public transportation’s fare.

Rheological Characteristics of Epoxidized Natural Rubber Modified Bitumen

Polymer modified bitumens have tended to be the most popular among the various types of modified binders that are available worldwide. Polymer modification significantly alters the rheological characteristics of the binder, thereby requiring the use of fundamental rheological testing methods to provide an indication of the performance of the binder and subsequently the asphalt mixture. In this paper the characterization of bitumen modified with epoxidized natural rubber (ENR) was done with four percentages of ENR content. The effects of the modifier on the conventional properties, storage stability and rheological properties were investigated. The results indicated that storage stability of ENR modified bitumens (ENRMB) were mainly dependent on the ENR content. ENR reduced the temperature susceptibility. The degree of the improvement generally increased with ENR content up to 9%.

Evaluating the Effect of Mixing Process on Nano-Clay Modified Binders Using the Pull-Off Test Method

Bonding strength of bitumen is one of the most important properties in need of independent evaluation. Conducting a pull-off test to determine the bonding strength of bitumen can be done using the Universal Test Machine (UTM). In this work, the UTM was used to investigate the effect of adding an additive to with a 60/70 penetration grade bitumen; the additive used was nano-clay at a percentage of 2% and 4%. A designed mold was fabricated and used with granite and stainless steel substrates. The investigation covered the influence of variation in the mixing process (mixing duration and power of rotation during mix) on the bonding strength of the samples. X-ray diffraction (XRD) was used to discover the nano-clay exfoliation within the binder structure. Also, empirical tests - penetration and softening point tests - were conducted. The results varied according to variation in percentage of additive, substrates used and the mixing process. The bonding strength and softening point results were able to identify the effect of the additive, and were able to detect changes caused by the adding condition; both were very well correlated, unlike the penetration test result which had a weaker correlation with bonding strength.

Engineering characterisation of epoxidized natural rubber-modified hot-mix asphalt

Road distress results in high maintenance costs. However, increased understandings of asphalt behaviour and properties coupled with technological developments have allowed paving technologists to examine the benefits of introducing additives and modifiers. As a result, polymers have become extremely popular as modifiers to improve the performance of the asphalt mix. This study investigates the performance characteristics of epoxidized natural rubber (ENR)-modified hot-mix asphalt. Tests were conducted using ENR–asphalt mixes prepared using the wet process. Mechanical testing on the ENR–asphalt mixes showed that the resilient modulus of the mixes was greatly affected by testing temperature and frequency. On the other hand, although rutting performance decreased at high temperatures because of the increased elasticity of the ENR–asphalt mixes, fatigue performance improved at intermediate temperatures as compared to the base mix. However, durability tests indicated that the ENR–asphalt mixes were slightly susceptible to the presence of moisture. In conclusion, the performance of asphalt pavement can be enhanced by incorporating ENR as a modifier to counter major road distress.

Life Cycle Assessment for Pavement Sustainable Development: Critical Review

Certainly, one of the most cost effective and comprehensive infrastructure assets of the build environment is road infrastructure. The environmental impacts of this asset during its life-cycle drive researchers to create a foundational framework to quantify these effects. Life cycle assessment (LCA), a method for the assessment of all modules in a life cycle, has been examined to evaluate all the environmental modules and components of road projects due to constraints of environmental assessments. The enthusiasm for enhancing the sustainable development of basic infrastructure leads to quick expansion on pavement life cycle assessment. An audit of applicable published LCA studies has recognized that environmental modules, such as the usage module (rolling resistance of pavement, carbonation, and albedo), end of life (EOL) module, and components such as traffic congestion during the construction module are not regarded in most of the articles. These modules potentially have the same environmental impact as other regularly considered modules such as materials, transportation, and construction. The goal of this study is to recognize shortfalls in the fields that bolster pavement LCA, to prepare a comprehensive and straight forward methodology, and to provide a basis on which related studies can move forward

Influence of diatomite filler on rheological properties of porous asphalt mastic

ABSTRACT Mineral filler is usually added into asphalt mixture to stiffen the asphalt binder and improve mixture strength. This is particularly important for open gradations such as porous asphalt which is known to have poor strength and durability because of its open nature and large air voids. The interactions that occur between asphalt binder and filler results in certain mastic properties that affect the mixture strength. In this study, the effect of different types of filler on the rheological properties of asphalt–filler mastics for porous asphalt were evaluated using the frequency sweep and multiple stress creep recovery (MSCR) tests. Hydrated lime, cement and diatomite with 2% content were selected to produce asphalt–filler mastic. The influence of diatomite filler was investigated and compared to the hydrated lime and cement fillers. Results indicated that the use of filler increased the stiffness of mastics. The MSCR test showed that hydrated lime and diatomite mastics exhibited the lowest non-recoverable compliance and high recovery than the original PG 76 binder and cement mastic. Diatomite mastic exhibits the best resistance to rutting at high temperatures and stress levels, verifying that the use of diatomite filler is favourable because of its high temperature properties.

Evaluation of Moisture and Ageing Effects on Calcium Carbonite Nanoparticles Modified Asphalt Mixtures

Flexible pavements deteriorate and crack with time due to the frequent traffic load imposed upon it. Many studies have been done to predict the effects of frequent traffic load and environmental conditions on pavements in the effort to find the best pavement design which resist deterioration and ensure longer pavement service time. This study investigates the effect of mixing asphalt with varying percentages of nano calcium carbonate (CaCO3), namely 0, 2, 4, and 6 %. The mixtures were designed based on the Superpave mix design criteria. Investigation was done using several tests, namely resilient modulus, indirect tensile strength, moisture susceptibility, and dynamic modulus tests. Samples were subjected to aging to determine their resilient modulus. The results of the investigation show that resilient modulus and indirect tensile strength increased when higher percentages of nanoparticles were added to asphalt mixture, with improvement of 138 and 48.18% respectively. Modified binders showed up to 17% improvement in moisture susceptibility comparison to base asphalt mixture, while the result of dynamic modulus test showed that the stiffness of modified asphalt increased 76.69%. The investigation also found that adding 6% CaCO3 nanoparticles to asphalt produced modified asphalt with the best performance. In addition, the results show that the modified asphalt with CaCO3 is suitable for hot and humid regions (tropical countries) in the field of highways construction, as the modifier was able to mitigate the influences of high-temperature rutting and moisture damage.

Effect of various filler types on the properties of porous asphalt mixture

The open structure of porous asphalt exposes a large surface area to the effects of air and water, which accelerates the oxidation rate and affects the coating properties of the binder. These factors may influence the adhesive strength of the binder-aggregate and lead to cohesive failure within the binder film, contributing to aggregate stripping and moisture damage. The addition of fillers in asphalt mixtures has been identified to stiffen the asphalt binder and improve mixture strength. This study investigates the effect of various filler types (hydrated lime, cement, and diatomite) on the properties of porous asphalt. Compacted samples of porous asphalt were prepared using Superpave gyratory compactor at the target air void content of 21%. Each sample was incorporated with 2% of filler and polymer-modified binder of PG76. The morphology and chemical composition of fillers were investigated with a field emission scanning electron microscope (FESEM) and energy dispersive X-ray (EDX) analysis. The properties of porous asphalt were evaluated in terms of permeability, abrasion loss, resilient modulus, and indirect tensile strength. All mixtures were found to show high permeability rates. Mixtures with hydrated lime exhibited lower abrasion loss compared to mixtures with cement and diatomite. The use of diatomite increases the resistance of the mixtures to rutting and moisture damage compared to other fillers as shown by the enhanced resilient modulus and indirect tensile strength.