Rejuvenation of hot mix asphalt incorporating high RAP content: Issues to consider

The asphalt used to construct or rehabilitation roads often contains reclaimed asphalt pavement (RAP) in order to diminish not only the use of raw materials but also waste. However, when high level of RAP in hot mix asphalt (HMA) is used, the rejuvenating agents must be employed. A number of aspects must be taken into account to increase pavement service life as much as possible. Thus, the main issues related to the rejuvenation of asphalt mixtures with high levels of RAP are addressed in this paper. In particular, the focal points of this paper will focus on the use of reclaimed asphalt mixtures with maximum efficiency, special attention is paid to how the binder is structured and chemically composes, nature and dose selection of rejuvenator, as well as the diffusion, blending efficiency, homogeneity, time and temperature mixing. A review of the extant and related literature shows that RAP utilization holds promise for the sustainable pavements, provided that some issues were taken into consideration during the designing and application process

Kinetic modeling of supercritical fluid extraction of betel nut

Supercritical fluid extraction is an advanced extraction technique that suitable for heat sensitive and active compound material from plants and herbs. Understanding the effect of extraction parameters on mass transfer coefficient at solid and fluid phase can determine the dominating extraction regime thus performance of the extraction may be enhanced. The aim of this research was to determine the mass transfer coefficient in solid and fluid phase using kinetic modelling approach. Grounded betel nuts were treated with supercritical carbon dioxide with 5% methanol as co-solvent to determine its mass transfer coefficient in solid and fluid phase for the following extraction conditions; pressure, 20 to 30 MPa; temperature, 50 to 70 °C; and flow rate, 2 to 4 mL/min. Simplified Sovová model was coupled with Broken and Intact Cell model to determine the mass transfer coefficients. Results show the mass transfer coefficients of solid phase and liquid phase are in the ranges of 0.00015 to 0.00353 m3/min and 0.3497 to 3.9623 m3/min, respectively. The overall absolute average relative deviation was observed to be 7.39%

Relationship between rutting, roughness and resilient modulus of flexible expressway pavement

The study was conducted to investigate the relationship between rutting, roughness and resilient modulus of flexible expressway pavement. The evaluation was conducted at Shah Alam Expressway from km 17.90 to km 52.20. The expressway consisted of three lanes for each bound (slow, middle and fast lanes). The scanner vehicle was used to evaluate the roughness and rutting of the entire test section and the roughness value was given in the International Roughness Index (IRI). While, the resilient modulus values for bituminous layer (E1), road base (E2) and subgrade (E3) were determined by Falling Weight Deflectometer (FWD). IRI and rutting values show that the expressway was in a good to satisfactory condition. In term of resilient modulus, most of the E1 and E2 layers were in the sound to satisfactory condition except 20.1% and 32.1% of the slow lane section was in poor condition, respectively. Resilient modulus of E3 for the entire section was in the sound to satisfactory condition. As a conclusion, the fast lane shows a better condition compares to the middle and slow lanes. In addition, poor correlation was found between rutting, roughness and resilient modulus respectively

Application of drying model to determine extraction behaviours on peanut skin oil recovery by supercritical carbon dioxide-ethanol

The main objective of this study was to determine the mass transfer for extraction of peanut (Arachis hypogea) skin by using drying models as alternatives extraction models. The mass transfer was measured at the pressure ranging from 10 MPa to 30 MPa, temperature of 40 oC to 70 oC, and rate of modifier 0.075 mL/min to 0.225 mL/min. The Lewis, Page, Peleg, Henderson and Pabis, and Avhad and Macetti as drying models were modified to illustrate the extraction process and to transform as alternative empirical models. An average absolute relative deviation percentage (AARD%) of Lewis, Page, Peleg, Henderson - Pabis, and Avhad-Macetti was 9.52%, 4.67%, 19.41%, 0.26%, and 0.04%. Avhad and Macetti model offered the best fitting between experimental data and modelling data. The results showed that drying model was applicable to correlate the experimental data of extraction process due to low percentage of error and high coefficient determination

Effect of different rejuvenating agents on the mechanical performance of recycled bituminous mixture

Reclaimed asphalt pavement (RAP) is a waste material generated from pavement milling activity. Rejuvenating agent is introduced to restore the properties of aging bitumen in RAP. Many studies have been investigated the performance of recycled mixture incorporating RAP with oil-based (OB) rejuvenating agent, but there is still limited research on water-based (WB) rejuvenating agent. Therefore, this study evaluated the performance of mixture incorporating RAP with OB and WB rejuvenating agents (RAP-OB and RAP-WB). OB and WB rejuvenating agents were added at recommended content of 0.70% and 52.13% by weight of bitumen, respectively. Indirect tensile strength, resilient modulus, dynamic creep and asphalt pavement analyzer (APA) tests were conducted to assess the resistance of the mixtures toward permanent deformation and fatigue cracking. It was found that the addition of OB rejuvenating agent enhanced the tensile strength, resilient and stiffness modulus by approximately 41%, 94% and 158%, respectively, relative to the control mixture. APA recorded that RAP-OB produced the lowest rut depth, followed by RAP-WB and control mixture. It indicates that RAP-OB produced the highest resistance to permanent deformation and fatigue cracking. Thus, the OB rejuvenating agent significantly improved the performance of the recycled mixture compared to the WB rejuvenating agent

Anthocyanins, phenols, and antioxidant activity in blackberry juice with plant extracts addition during heating

In this work the influence of addition of different plant extracts (olive leaf, green tea, pine bark PE 95%, pine bark PE 5:1, red wine PE 30%, red wine PE 4:1, and bioflavonoids) to blackberry juice during heating (at 30, 50, 70 and 90 °C) on the anthocyanin and phenol contents, polymeric colour, and antioxidant activity was investigated. Also, reaction rate constant, half-lives of degradation, and activation energy were calculated. Control sample was juice without addition of extracts. The highest anthocyanin content at 30 °C was in samples with the addition of olive leaf and green tea. At 90 °C the highest anthocyanin content was measured in samples with the addition of extract of red wine and bioflavonoides. Samples supplemented with the extracts had much higher antioxidant activity in comparison to the control sample. Results showed that at 90 °C the sample with green tea supplementation had the lowest reaction rate constant and the highest half-life. Activation energy ranged from 29 to 44 kJ mol−1

Influence of pavement condition towards accident number on Malaysian highway

Accidents in Malaysia are alarming and have been in the rise for the past decades. Increasing numbers of road users, condition of road surface, expanded road network and weather conditions are being carefully looked into determining the contributors towards fatality. Human factors has been widely known and established as one of the main contributor to road accidents. Therefore, this study had focused more on to pavement conditions, where its relation with accidents needs to be further explored. The purpose of this study is to determine the influence of pavement condition towards accident number on Malaysian Highway. Pavement condition data which consist of Mean Texture Depth (MTD), Rutting Depth (RD) and also International Roughness Index (IRI) were measured along 265 km southern stretch of Malaysia highway, by using Multi Laser Profiler (MLP). Accident data were also collected from the accident report prepared by Southern region of Malaysian Highway Authority. Based on the results, it was found that more than 70% of the accidents happened at a good condition of road which having high MTD, low RD and minimum IRI. MTD was found as the most significance parameters that relates to accident. Other factors such as human negligence and environments (weather and lighting), might be the major cause that contribute to the accidents that happened along Malaysian highway