Ibrahim Kamaruddin

Nanosilica composite asphalt mixtures performance-based design and optimisation using response surface methodology

Abstract In recent times, the use of polymer nanocomposite for construction of durable asphalt mixtures has been gradually replacing the application of polymer-modified binders. In this investigation, the optimisation of nanosilica and binder content for nanocomposite-modified asphalt mixtures has been examined to obtain optimum quantities for high-performance properties. Response Surface Methodology (RSM) was applied for the optimisation based on central composite design (CCD). Interaction effects of two independent variable factors, nanosilica and binder content, on nanocomposite strength, volumetric and performance properties were analysed using CCD design. The responses were analysed using RSM, and models were developed to fit the experimental results for prediction of the responses. The results indicate that the individual effects of nanosilica and binder content are both important for performance improvement. Based on the numerical optimisation, 1.5% nanosilica and 5% binder content were found to be the optimal values. Also, the mean error obtained from optimisation results are all less than 5% for all responses, indicating that predicted values agree with experimental results and the developed models fit to the experimental results. Furthermore, the study concluded that for composite asphalt mixture design with high-performance properties, optimisation using RSM is a very good approach.

Rheological and rutting evaluation of composite nanosilica/polyethylene modified bitumen

In this research, composite nanosilica/polyethylene modified binder samples were prepared at varying concentration of nanosilica. The modified binder samples are prepared by adding 1, 2 and 3 nanosilica by weight of bitumen in to 6 linear low density polyethylene (LLDPE) polymer modified binder. Effects of nanosilica on physical and rheological properties of composites were investigated through penetration, softening point, temperature susceptibility, dynamic mechanical analysis and rutting resistance evaluations. Results shows that, nanosilica affects the rheological properties of LLDPE modified binder due to decrease in penetration and increase in softening point observed with increase in nanosilica content, this enhances composite binders hardness and resistance to temperature. Temperature susceptibility shows that, composite modified binders are less susceptible to temperature compared to LLDPE modified binder. DSR rheological analysis shows that, nanosilica enhances the composite modified binders properties at intermediate to high temperatures. Also rutting parameter evaluation indicates that composite modified binders have high resistance to rutting deformations due to increase in elastic behavior and stiffness of the composites.

The Utilization of Rice Husks Powder as an Antioxidant in Asphalt Binder

Aging is one of the main contributors for asphalt failure. Oxidation aging is the main cause of long-term deterioration in asphalt pavements as a pavement ages, oxidation stiffens a pavement, making it more susceptible to failure from load and thermal stresses. Slowing a pavement’s oxidative aging would maintain its elastic properties and delay aging problems. There is no performance enhancer in widespread use, acting as an antioxidant that slows the oxidative aging of asphalt binder. The main objective of this research is to investigate the feasibility of using biomass powder derived from rice husks as an antioxidant additive to control the asphalt age hardening. The waste of rice husks was dried at 40°C for 9–11 days. The dried materials was grounded, and sieved to get fine powder. To evaluate the performance of the antioxidant, samples have to be aged according to SUPERPAVE standards (RTFOT and PAV) and physical, chemical, and rheological properties have to be analyzed. The preliminary results of penetration test softening point test shows that adding 4% of rice husks’ powder to 80/100 binder didn’t change the grade of the binder.

The Use of Bitumen Linear Viscoelastic Properties to Assess Rutting Sensitivity

The use of viscosity temperature relationships to predict creep performance of road bitumens have been shown to be inadequate in particular with respect to the analysis of polymer modified binders. In this paper we explore the origins of the US Strategic Highway Research Programmebinder performance grading system and detail two examples of more recent developments towards improved creep characterisation.Starting from first principles, an equation to analyse the ratio of dissipated to stored energy during sinusoidal loading of viscoelastic bitumen was derived. The energy equation was contrasted with an empirical relationship proposed by Anderson D.A., and with a second more theoretical derivation proposed by Shenoy A.Using frequency sweep data from a conventional 40/50 pen grade bitumen and a proprietary SBS modified binder, the applicability of the energy equation was subsequently compared to the two aforementioned post-SHRP creep relations. Recommendations are made regarding the suitability of the proposed relations in ranking bitumen creep performance.

Influence of nanosilica on moisture resistance of polymer modified bitumens

ABSTRACT In this research, the effects of nanosilica and polymer on moisture resistance and other properties of hot mix asphalt have been investigated. The asphalt binder was modified using polyethylene and polypropylene polymers with varying percentages of nanosilica. The Marshall stability, flow, indirect tensile strength, stiffness modulus and resistance to moisture damages test tensile strength ratio (TSR) and retained Marshall stability (RMS) tests were conducted. The results show that application of nanosilica improves the stability, reduces optimum binder content, increases stiffness as well as strength characteristic of the asphalt mixtures. Moisture damage analysis of the modified mixtures shows a good enhancement due to addition of nanosilica particles.

Compatibility of Plastomeric Modified Bituminous Blends: Its Effect on the Performance Behavior of Modified Bituminous Mixture

This paper present a part of research study conducted to investigate the effect of compatibility of polymer bitumen blend on the performance behavior of the well graded bituminous concrete mixture. Bituminous mixture was prepared by using 80/100 Pen bitumen for control mix, while polyethylene modified mixture was prepared by blending linear low density polyethylene (LLDPE) with 80/100 Pen bitumen. The concentration of polymer in the blend was kept at 1, 2 and 3 % by weight of bitumen content. The compatibility of polymer bitumen blend as revealed by morphological analysis using transmission electron microscopy (TEM) shows that as the concentration of polymer in bitumen increases the formation of polymer network was observed. It was found that at higher polymer concentration formation of polymer bitumen network considered responsible for improved performance which was also confirmed by dynamic creep results of the modified bituminous samples.

IDENTIFICATION AND MODELLING PROCESS OF DEFINING TEMPERATURE GRADIENT IN AIRPORT PAVEMENT

AbstractPreserving airport pavement means guarantying the safety operation of aircraft movements. There are four aspects that cause progressive pavement deterioration, i.e. the construction design and process, selected material, and maintenance management. One of the traffic aspects, jet engine exhaust, has not been discovered yet. The load pattern of the jet exhaust follows the schedule of aircraft traffic. The assumption held in this research is that the thermal load during aircraft movement may generate a high temperature, which is induced into pavement layers. The objective of this research is to determine the temperature gradient in the pavement, caused by the jet exhaust. This paper discusses the process of determining the temperature gradient in four stages, i.e. by carrying out the gap analysis, evaluation of pavement structures, determination of the load path and the magnitude, and defining the temperature gradient. The temperature gradient in the pavement layer is determined through the developm...

Low Energy Compaction of Aggregate Packing Mechanism

Aggregate packing mechanism and its properties are always significant in the compaction, density and consequential strength and resistance of the bituminous mixture. Realizing that aggregate interlocking contributes to the strength, the packing of aggregate would increase the force of intact between aggregates. This work is focused on improving the compaction energy, engineering properties and rutting resistance of bituminous mixture by using the aggregate packing concept. After obtaining the optimum proportions for developed mixture via packing test, hot-mix asphalt samples are prepared and compacted with 50 and 75 blows, while well graded hot-mix asphalt samples are compacted with 75 blows. The Marshall Test result showed that developed mixture at lower compaction energy meets all the requirements of asphaltic concrete for heavy traffic and also exhibit higher density, stability, and lower air voids and voids in mineral aggregate compared to the well graded mixture. Developed mixture also demonstrated higher mixture stiffness and lower rut depth compared to the well graded one. This is due to the optimal distribution of the various aggregates sizes of developed mixture, which gives the interlocking necessary and stone to stone contact to improve the mixture density, stiffness and rutting resistance.

Effect of Polymer Dispersion on the Rheology and Morphology of Polymer Modified Bituminous Blend

Increase in axle wheel load and traffic volume has led to the use of polymer modified bitumen (PMB) on roads as it offers better rutting, thermal and fatigue performances. In this paper the viscosity function of PMB obtained at 135°C was studied in the context of polymer dispersion in the bitumen blend. Polypropylene (PP) was used as the modifier for 80/100 pen bitumen. The morphological analysis using Scanning Electron Microscopy (SEM), Atomic force Microscopy (AFM) and Field Emission Electron Microscopy (FESEM) were presented. It was found that although the polymer resin was not fully digested by the virgin bitumen, there was evidence of a significant alteration of the Newtonian behavior of virgin bitumen to non-Newtonian behavior by the addition of the polymer.Presence of thixotropic behavior in the blend can be considered benefical in recovery of stress related deformation. SEM examination of PP resin revealed that partial breakage of the periphery of the resin was sufficient to enhance the viscosity of the PMB significantly. AFM phase images revealed that up to 2% polymer concentration in bitumen significantly enhances the viscoelastic property of the final PMB blend.The phase separated layer in PMB blend with sufficient stiffnesss and viscoelastic property of PP also acts as stress relaxant surface. Thus the PMB benefited by the incorporation of the polymer as it induces phase separated layer in the blend that can potentialy offer better fatigue and cracking properties to the resulting mix.

Effect of Fine Aggregate Physical Properties on the Engineering Properties of Conventional and Polymer-Modified Bituminous Mixtures

Most studies on hot-mix asphalt have used crushed fine aggregate and gravel; research regarding the use of mining sand or marine sand as fine aggregate is limited. This work investigates the effects of fine aggregate physical properties on the engineering properties of hot-mix asphalt. Four types of sand (quarry, river, mining, and marine sand) with two conventional binders (PEN 50/60 and PEN 80/100) and four types of polymer-modified bitumen (PMB) (PM1_82, PM1_76, PM2_82, and PM2_76) were used. Electron microscopy scanning was performed along with sieve analysis and tests for specific gravity and angularity of the fine aggregate on the different types of sand to determine their properties and thereby examine the effects of these properties when the sands were incorporated into a bituminous mixture. Marshall test results showed that fine aggregate physical properties influenced the optimum bitumen contents and engineering properties. The study also revealed that angular and rougher particles of fine aggregate produced lower voids in mineral aggregate, lower optimum bitumen content, higher shear strength, and higher density, which consequently increased the stability of the resulting mixtures. Moreover, a polymer-modified bituminous mixture enhanced stability and stiffness, reduced density, and slightly increased the voids in mineral aggregate.