Meor Othman Hamzah

Effects of Sasobit® content on the rheological characteristics of unaged and aged asphalt binders at high and intermediate temperatures

Summary of analysis of variance (ANOVA) for AI. Source Sum of squares df Mean square F p-Value Significant Corrected model 22.41 a 45 .498 16.01 <0.001 YesIntercept 407.07 1 407.07 13090.28 <0.001 YesM 8.05 1 8.05 259.07 <0.001 YesB 0.78 2 0.39 12.53 <0.001 YesS 2.44 2 1.22 39.25 <0.001 YesT 1.79 2 0.89 28.77 <0.001 YesM * S 1.87 2 0.94 30.10 <0.001 YesM* T 1.19 2 0.596 19.17 <0.001 YesB * S 0.43 4 0.11 3.50 <0.001 YesB * T 0.63 4 0.16 5.09 <0.001 YesS* T 1.28 4 0.32 10.31 <0.001 YesM * B * S 0.48 4 0.12 3.82 <0.001 YesM* B * T 1.21 4 0.30 9.78 <0.001 YesM* S * T 0.89 4 0.22 7.20 <0.001 YesB* S * T 0.49 8 0.06 1.99 <0.001 YesError 5.28 170 0.03Total 482.25 216Corrected total 27.69 215 a R Squared =0.81 (Adjusted R Squared 0.76), M: Method or type of rheological property; T: Temperature, B: Binder type; S: Sasobit ® content; *: Interaction. Figure 13. Relationship between the high failure temperatures of unaged (FT U ) and short-term-aged (FT

Laboratory simulation of the clogging behaviour of single-layer and two-layer porous asphalt

The permeability of porous asphalt (PA) reduces after a few years in service due to clogging. The two-layer porous asphal (TLPA) was developed to mitigate this problem. This paper presents a laboratory-simulative clogging test of single-layer and TLPA using a falling-head water permeameter. The resistance to clogging of the PA specimens was evaluated by subjecting specimens to five clogging and cleansing cycles. All clogging tests were carried out at an ambient temperature. To evaluate the effects of temperature on clogging resistance, the clogging test procedure was also conducted on selected specimens but conditioned at 10°C, 30°C and 50°C. The test results showed that a significant permeability loss took place during the first few clogging and cleansing cycles, beyond which it asymptotes. The TLPA specimens can better resist clogging compared with the single-layer PA specimens. Binder content significantly affects clogging behaviour, while specimens conditioned at higher temperature were more susceptible to clogging compared with specimens conditioned at lower temperatures.

Evaluation of the Rheological Properties and Activation Energy of Virgin and Recovered Asphalt Binder Blends

AbstractIn this study, the rheological properties and activation energy (AE) of unaged and aged asphalts blended with different percentages of binder, recovered from three reclaimed asphalt pavement (RAP) sources, were investigated. Superpave asphalt binder tests were used to evaluate the effects of the recovered asphalt binder source and content. The results indicated that the addition of recovered binder from each source increased the viscosity, G*/sinδ, and G*sinδ. The increase in viscosity per 1% recovered binder was evaluated using non-dimensional viscosity index (∇ηRAP). In addition, the increase in G*/sinδ and G*sinδ per 1% recovered binder were investigated using relative Superpave rutting gradient (RSRG) and relative G*sinδ gradient (RG) factors, respectively. The results indicated that the ∇ηRAP, RSRG, and RG depended on recovered binder source, content, aging, and test temperature. The interpretation of the AE results depended on the physical phase of the asphalt blends, irrespective of the rec...

Parameters to characterise the effects of Sasobit® content on the rheological properties of unaged and aged asphalt binders

Incorporation of warm asphalt additives in conventional asphalt binder affects its rheological properties. This paper presents two Superpave™ binder parameters that were used to characterise the rheological properties of PG64 and PG70 asphalt binders blended with various Sasobit® contents and subjected to high and intermediate temperatures as well as under different ageing conditions. The parameters used to characterise the binder rheology at high and intermediate temperatures were the non-dimensional viscosity gradient (∇ η S ) and non-dimensional Superpave™ rutting parameter (NSRP), respectively). The results indicated that the ∇ η S trends differ depending on binder types, test temperatures and ageing conditions. The NSRP exhibited a significantly different trend for each Sasobit® content, depending on binder type and ageing conditions.

Evaluation of Rediset for use in warm-mix asphalt: a review of the literatures

This literature review paper presents the effects of a chemical warm mix additive, named Rediset on the rheological properties of asphalt binders, laboratory performance of asphalt mixtures, field behaviour of constructed road sections, energy consumption and air pollution, physicochemical properties of asphalt binders and behaviour of asphalt mortar. The rheological effects of Rediset on asphalt binder were evaluated from the viewpoint of very high temperature properties (viscosity of asphalt binder and workability of asphalt mixtures), high temperature properties (rutting resistance of asphalt binders and mixtures), intermediate temperature (fatigue behaviour) and also low temperature cracking properties. Other topics such as the mechanisms of temperature reduction by Rediset, storage stability of Rediset modified binders, moisture susceptibility, mix design issues, volumetric properties and economic benefits were also investigated. The information reported in this paper will help decision makers to appropriately select, apply and evaluate this warm additive type. In addition, researchers can identify gaps in existing knowledge for future research.

Rheological Evaluation and Modeling of Sasobit®-Modified Asphalt Binder at High Temperatures

Warm mix asphalt using Sasobit® (Sasol Wax Company, Sasolburg, South Africa) is a new technology to reduce construction temperatures of asphalt mixes. This article presents the rheological properties of Sasobit-modified asphalt binder at high temperatures using response surface methodology. The results showed that the temperature at which the asphalt binder was blended with Sasobit had no effect on the high-temperature properties of Sasobit-modified asphalt binder, including viscosity and viscosity–temperature susceptibility, at each aging state. All empirical viscosity and aging models of Sasobit-modified asphalt binder follow second-order polynomial trends with test temperature, Sasobit contents, and their interactions at each aging condition.

Properties of Porous Asphalt Mixture Made with Styrene Butadiene Styrene under Long Term Oven Ageing

Oven ageing is a set of procedure to simulate the accelerated effects of ageing on pavements structures. In this study, the effect of long-term oven ageing on porous asphalt mixture made with SBS modified binder was investigated. The resilient modulus, water permeability and air voids test results were the performance indicators used to evaluate the effects of ageing. The test results showed that, the resilient modulus of long term aged specimens was higher than those of unaged specimens. From the permeability test results, unaged SBS mixes exhibit lower coefficient permeability compared to the corresponding long-term oven age specimens. Most likely, ageing caused binder hardening, making the mix more difficult to compact and hence exhibited more continuous voids which in turn lead to higher permeability. In addition, the coefficient of permeability decreases as the binder content increased.

Estimation of optimum binder content of recycled asphalt incorporating a wax warm additive using response surface method

Abstract This paper presents a new approach to estimate the optimum binder content (OBC) of recycled asphalts (RAs) incorporating a warm mix additive based on the interaction effects of compaction temperature, RA content and binder content using volumetric and strength characterisation. The experimental design was developed using response surface method (RSM) based on central composite design for various compaction temperatures (130–160 °C), RA contents (30–50%) and binder contents (4.9–6.0%). Laboratory tests were performed and analysed to meet the desired volumetric and strength properties according to the Malaysian specifications for the design of dense asphalt mixtures. Statistical analysis and mathematical models proposed by RSM were used to determine the OBC. The results showed that compaction temperature is the most significant factor in determining the OBC. There are minimum differences in the OBC variation of samples incorporating different dosage of RA. The developed model can be used for quick estimation of OBC for various levels of compaction temperature and RA content.

Development of Dynamic Asphalt Stripping Machine for Better Prediction of Moisture Damage on Porous Asphalt in the Field

Stripping is a major source of pavement distress and takes place in the presence of moisture. Over the years, many laboratory tests have been proposed to evaluate moisture sensitivity of asphalt mixtures. This paper presents the development of a dynamic asphalt stripping machine (DASM) to realistically simulate stripping of porous asphalt mixtures subjected to the dynamic action of flowing water. To assess the effectiveness of the machine, two sets of specimens were prepared. One set was conditioned in the DASM by allowing water at 40oC to continuously permeate through the unextruded samples via water sprinklers at an intensity equivalent to 5400 mm/hr. The other set was stored under dry conditions at ambient temperature. Then, both sets of specimens were extruded and conditioned in an incubator before individually tested for Indirect Tensile Strength (ITS) at 20oC after 1, 3, 5 and 7 days. Resistance to stripping was evaluated from the ratio between ITS when tested wet and dry. Specimen permeability was also measure before and after conditioning. In addition, mortars that stripped from the asphalt samples were filtered on a filter material. The results showed that both ITSR and permeability reduces with conditioning time. The ITSR after 7-day conditioning was 17.2% lower than those conditioned for one day. The quantity of mortars collected on the filter material was found to increase with conditioning time. However, some stripped mortars were believed to be trapped in the mixture capillaries, and this explained the reduction in coefficient of permeability values over time.

A Proposal to Characterize the Angular Speed and Acceleration of the Torsional Recovery of a Polymer-Modified Asphalt Binder Incorporating Synthetic Wax

The objective of this study is to propose a simple methodology based on the Newtonian mechanics or classic kinematic laws for the characterization of the average torsional recovery speed (ω) and the torsional recovery acceleration (ώ) of a polymer-modified asphalt binder incorporating a type of synthetic wax as a warm mix additive. The correlation of the rheological properties of the modified binder in terms of the torsional recovery (TR), along with the engineering properties of prepared warm mixture asphalt in terms of resilient modulus (MR) and indirect tensile strength (ITS), were evaluated. The results indicated that TR, ω, and ώ of the asphalt binders increase as the synthetic wax content increases. The results also indicated that TR, ω, and ώ have strong correlations with rutting factor (G*/sin δ), non-recoverable creep compliance (Jnr), and recovery percentage (R) of the asphalt. Moreover, there is a significant relationship between the parameters of TR, ω, and ώ and the engineering properties of the mixture samples, irrespective of the construction temperatures.