Moisture susceptibility and environmental impact of warm mix asphalt containing bottom ash

Warm Mix Asphalt (WMA) is recognised as a sustainable pavement construction technology due to its economic and environmental benefits. However, there are still some major concerns related to its performance properties, like moisture susceptibility. Certain researchers have reported desired performances using waste and by-products as constituent material in the WMA mixture. Therefore, this study was proposed to assess the Bottom Ash (BA) impact on WMA mixtures moisture susceptibility and environmental properties because its potential has widely been reported in HMA. It was limited to 20 % of fine aggregate substitution with BA and granite stone dust as a filler. Evotherm 3G was used as a WMA additive, and the Hot Mix Asphalt (HMA) mixtures were treated with 2 % hydrated lime by replacing stone dust. The Marshall mix design was followed to fabricate asphalt mixtures, where HMA and WMA specimens were mixed at 165 °C and 140 °C, respectively. The indirect tensile strength, tensile strength ratio, toxicity characteristic leaching procedure (TCLP) and pollutant emission of mixtures were investigated through laboratory tests. The mixtures containing BA improved the indirect tensile strength of mixtures, while Evotherm 3G potentially improved the tensile strength ratio of WMA mixtures containing BA. The results showed that BA as a constituent of asphalt mixture coupled with Evotherm 3G produced a compatible blend for WMA. The findings of the TCLP test showed that the compound of heavy elements found in BA does not leach out if introduced in the asphalt mixtures. Heavy elements concentrations were either undetectable or below the minimal level. However, the presence of BA in the asphalt mixture slightly increased the level of Carbon dioxide (CO2). However, the carbon monoxide (CO) of the WMA mixture containing BA was reduced to approximately 75 %

Mechanical performance of asphalt mixture containing cup lump rubber

The use of cup lump rubber as an additive in asphalt binder has recently become the main interest of the paving industry. The innovation helps to increase the natural rubber consumption and stabilize the rubber price. This study evaluates the mechanical performance of cup lump rubber modified asphalt (CMA) mixture in terms of resilient modulus, dynamic creep and indirect tensile strength under aging conditions. The CMA mixture was prepared using dense-graded Marshall-designed mix and the observed behavior was compared with that of conventional mixture. From the results, both mixtures passed the volumetric properties as accordance to Malaysian Public Work Department (PWD) specification. A comparable result was obtained for stability and indirect tensile strength. The addition of 5% cup lump rubber provides better resistance against permanent deformation through the enhanced properties of resilient modulus and dynamic creep by 27% and 126% respectively under unaged condition. Furthermore, lower permanent strain was also observed for CMA compared to conventional mixture

Laboratory investigation of coal bottom ash modified warm mix asphalt

Bottom Ash (BA), a coal combustion by-product, found to be a potential material when used to produce asphalt mixture. However, some of its characteristics make it a questionable material for the surface course. Therefore, this study aims to evaluate the compatibility of BA in Warm Mix Asphalt (WMA) technology through the basic mechanical properties of the asphalt mixtures for binder course layer (AC 28). Two WMA chemical additives, Cecabase RT and Evotherm 3G, were used at the concentrations of 0.3, 0.4 and 0.5% from the binder's weight. The binder properties were assessed through penetration, softening point and viscosity tests. The Marshall mix design was used to determine the optimum binder content (OBC). The additive dosage and production temperature for WMA were determined through Marshall stability, flow, air voids and specific gravity. The results show that the additives did not significantly affect the binder properties, although, at 0.4% Evotherm 3G, a drop of 17.5% in penetration was observed. Cecabase RT produced WMA with promising results but did not enhance the workability of WMA containing bottom ash (BAWMA). By lowering the production temperature of 25 °C, WMA and BAWMA at 0.4 %, Evotherm 3G demonstrated comparable workability to the conventional Hot Mix Asphalt (HMA). The data achieved through this study would be a guiding approach towards the application of BA in WMA technology for sustainable pavements

Evaluation on the performance of aged asphalt binder and mixture under various aging methods

Hot mix asphalt (HMA) pavement encounter short and long term aging throughout the service life. Laboratory aging is the method used to simulate field aging process of HMA pavement. This study was undertaken to determine the long term effect of different binder and mixture laboratory aging methods on HMA (binder aging and mixture aging). Three types of HMA mixtures were prepared for this study namely Asphaltic Concrete with 10 mm nominal maximum aggregate size (AC 10), Asphaltic Concrete 14 mm (AC 14) and Asphaltic Concrete 28 mm (AC 28). These specimens were conditioned with nine different methods and durations. Resilient modulus test was carried out at 40°C as an initial indicator of the specimen performance. Permanent deformation of the same specimens was then evaluated by dynamic creep test. Generally, the aged asphalt binder specimens have higher resilient and stiffness modulus compared to aged asphalt mixture specimens. In addition, aged binder specimens have a lower permanent strain which indicates higher resistance to permanent deformation. This study also found that high resilient and stiffness modulus of specimens is attributed by different in heating frequency, temperature, air exposure and binder content of the mixture

A review of performance asphalt mixtures using bio binder as alternative binder

This paper provides an overview of the performance in asphalt mixture using bio-binder from biomass as alternative binder. The bio-binder considered from the previous research was produced by pyrolysis process. The aim of this study is to review the performance of asphalt mixture modified by bio-binder. The Rotational Viscometer (RV), Dynamic Shear Rheometer (DSR), Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV) and Bending Beam Rheometer (BBR) were conducted to evaluate the rheological properties of bio-binder in asphalt mixtures. Many previous studies focused on the chemical composition, physical properties and performance of bio-binder in asphalt mixtures. Several research studies have evaluated the viability of bio-binder in asphalt pavement mixtures. Therefore, in many of these case the bio-binder was evaluated in minimal proportions (<10 percent). This is necessary in order to identify a mixtures containing bio-binder at higher blending proportions (up to 50% replacement). Additionally, a review will be a positive step in the direction of achieving mixture modified with bio-binder has shown similar or improved performance when compared to conventional mixtures

Properties of dense-graded asphalt mixture compacted at different temperatures

Poor compaction work is one of the identified causes of road failure and has always been a concern to the asphalt industry. The use of compaction machinery, compaction temperature, weather factor and the type of mixture used could potentially affect the asphalt pavement performance. This study measures the properties of hot mix asphalt (dense-graded AC10) prepared at different compaction temperatures. Various compaction temperatures were selected for the laboratory slab samples preparation i.e. 152°C, 142°C, 132°C and 122°C. A 60/70 pen bitumen was used to prepare the slab with the size of 305mm x 305mm x 50mm. Thermocouple was used to monitor the temperature of the mix. The slab samples were then cored for cylindrical samples at the approximate size of 100mm diameter for mechanical tests. The core samples were tested for volumetric properties, degree of compaction (DOC), Marshall stability and resilient modulus. It was found that low compaction temperature increases the air void in the total mix (VTM) and decreases the air void filled with bitumen (VFB) due to the increase in bitumen viscosity. In other words, reduction in compaction temperature resists the compactibility of the loose mix and resulted in low final DOC and low modulus

Nephrotoxicopathology properties of gold and iron oxide nanoparticles with Perchloric Acid & SiPEG as radiographic contrast media

Introduction: Exponential research and development of nanotechnology has lead to its implementation in medical line such as radiographic imaging. In current practice, iodine is clinically used as a contrast media in radiographic analyses. However, contraindication of iodine to kidney in clinical practice warrants for a better contrast enhancer with lower toxicity. Gold nanoparticles (GNPs) and Iron Oxide nanoparticles (IONPs) have been proposed as potential iodine’s substitute due to their novel biocompatibility. Methods: In accordance with technology-driven toxicity impact, an animal modeling study has been conducted to assess the nephrotoxicopathology of GNPs and IONPs with Perchloric Acid and SiPEG by biochemical study, in-depth tissue examination by histopathology, apoptosis, and ultrastructural observation, and molecular analysis by Comet Assay. Results: Renal function test (RFT) revealed significant alteration in iodine group compared to nanoparticles and negative control group (p<0.05). Reactive oxygen species (ROS) generation and lipid peroxidation (MDA) levels demonstrated significant reduction in both nanoparticles’ groups compared to iodine (p<0.05), suggesting for lower oxidative stress induction. Morphological aberration demonstrated by histology and ultrastructural evaluation (TEM) showed a distortion in kidney tissues and nucleus’ structure of iodine-administered group as compared to control and nanoparticles’ group. Apoptosis detection by TUNEL assay for GNPs and IONPs group also revealed a significant reduction in apoptotic cells compared to iodine group. Comet assay revealed significant reduction in DNA damaging effect of GNPs and IONPs group compared to iodine group. Conclusion: The present study may postulate that GNPs and IONPs show better contrast enhancer properties with lesser toxic properties than iodine

Properties of high strength concrete containing spent garnet as sand

Spent garnet is a waste resulting from abrasive media known as garnet and disposed into the landfill which can become threat to the environment. Meanwhile, the step of substituting sand by spent garnet can reduce sand exploitation activities which have been ongoing to fulfil the continuous development and construction. This work attempts to investigate the mechanical properties of specimens made of concrete that contains spent garnet. This new material replaces sand partially at different percentages of 10% and 20% by weight. The compressive strength test as well as splitting tensile test have been both conducted after 7 days and 28 days water curing. The results show an improvement of the strength during the compressive test. The increment appears to be in positive relationship with the replacement percentage. Meanwhile, splitting tensile strength testing shows that 20% performs better than 10% sand replacement. In conclusion, the inclusion of spent garnet in reasonable amount to take place instead of sand has improved the concrete's properties

Effect of black rice husk ash on asphaltic concrete properties under aging condition

The scarcities of natural resources and increment in waste production rates have promoted efforts to investigate the potential incorporation of various by-products in roads construction. Reusing of waste materials such as black rice husk ash (BRHA) in asphaltic concrete was considered as one of the proper management of the waste, which ensures economic and environmental benefits. Hence, this study investigates the effect of black rice husk ash on asphalt mixtures properties under different aging condition. BRHA was added in the asphalt mix in a proportion of 0%, 2%, 4% and 6% by weight of bitumen. 5% optimum bitumen content with 60/70 penetration grade binder was selected for this study. The asphalt mixtures for each fraction was prepared in three different aging conditions i.e. un-aging (UA), short term aging (STA) and long term aging (LTA). The properties of asphalt mixtures were evaluated by voids, stiffness and dynamic creep tests. The results indicate that asphalt mixtures consisting of BRHA have exhibited better performance in term of voids, stiffness and creep modulus when compared to the conventional asphalt mixtures. The STA and LTA mixtures modified with BRHA produced higher performance than the unmodified mixtures. It can be concluded that the optimum additional percentage of BRHA was in the range of 4% to 6%

Enhanced dry process method for modified asphalt containing plastic waste

In recent years, the proliferation of plastic waste has become a global problem. A potential solution to this problem is the dry process, which incorporates plastic waste into asphalt mixtures. However, the dry process often has inconsistent performance due to poor interaction with binder and improper distribution of plastic waste particles in the mixture skeleton. This inconsistency may be caused by inaccurate mixing method, shredding size, mixing temperature and ingredient priorities. Thus, this study aims to improve the consistency of the dry process by comparing the control asphalt mixture and two plastic waste-modified asphalt mixtures prepared using the dry process. This study used crushed granite aggregate with the nominal maximum aggregate size of 14 mm whereas the shredded plastic bag is in the range of 5–10 mm. Quantitative sieving analysis and performance tests were carried out to examine the effects of plastic waste added into the asphalt mixture. The volumetric and performance properties combined with image analysis of the modified mixtures were obtained and compared with the control mixture. In addition, the moisture damage, resilient modulus, creep deformation and rutting were evaluated. This study also highlighted in detail the distribution of plastic particles in the final skeleton of the asphalt mixture. Based on the analysis, an enhanced dry process of mixing procedure was proposed and evaluated. Results showed that the addition of plastic particles using the conventional dry process leads to the deviation in the aggregate structure as high plastic content is added. Furthermore, the enhanced dry process developed in this study presents substantial enhancement in the asphalt performance, particularly with plastic waste that accounts for 20% of the weight of the asphalt binder