During recent decade, the pavement sustainability has received much attention by road agencies, companies, governments and research institutes. The aim of this paper is to introduce and evaluate the sustainability of the technologies developed or underdeveloped to address environmental issues of asphalt mixtures, and the waste materials and by-products that can be recycled and reused in asphalt production. Warm Mix Asphalt (WMA) technology, the most popular waste materials to substitute neat binder (crumb rubber modifier (CRM), recycled plastic (RP), vacuum tower bottoms (VTB)) and/or virgin aggregates (reclaimed asphalt pavement (RAP), reclaimed asphalt shingles (RAs), construction and demolition (C and D) wastes, steel and copper slags), and bio-binders were evaluated with respect to their environmental and economic benefits and engineering performance as the main components of pavement sustainability. The performance evaluation was carried out by examining rutting, moisture susceptibility, thermal and fatigue cracking resistance. Two main environmental impacts, greenhouse gas (GHG) emission, and energy consumption were considered to study the environmental effects of these technologies and materials. Additionally, the economic effect was investigated considering initial cost and long-term benefit. Results of investigation illustrated that although each individual technology and waste material is valuable in terms of performance and/or the environment, specific combinations such as WMA + RAP, WMA + CRM, RAP + CRM, and WMA + CRM + RAP lead to further benefits. Notably, these combinations suffer from a lack of comprehensive economic analysis, thus, their sustainability cannot be fully assessed and is prone to future studies.

Sustainability Assessment of Green Asphalt Mixtures: A Review

Marine plastic pollution and affordable housing challenge: Shredded waste plastic stabilized soil for producing compressed earth bricks

https://pubs.rsc.org/en/content/articlepdf/2019/cc/c9cc02861g

Upcycling a plastic cup: one-pot synthesis of lactate containing metal organic frameworks from polylactic acid.

The failure of bituminous pavements takes place due to heavy traffic loads and weather-related conditions, such as moisture, temperature, and UV radiation. To overcome or minimize such failures, a great effort has been put in recent years to enhance the material properties of bitumen, ultimately improving field performance and increasing the pavement service life. Polymer modification is considered one of the most suitable and by far the most popular approach. Elastomers, chemically functionalised thermoplastics and plastomers * (* Note: notwithstanding the fact that in Polymer Science the word ‘plastomer’ indicates a polymer with the simultaneous behaviour of an elastomer and plastics (thermoplastics), this paper uses the term ‘plastomer’ to indicate a thermoplastic polymer as it is more commonly found in Civil and Pavement Engineering.) are the most commonly used polymers for bitumen modification. Plastomers provide several advantages and are commonly acknowledged to improve high-temperature stiffness, although some of them are more prone to phase separation and consequent storage instability. Nowadays, due to the recent push for recycling, many road authorities are looking at the use of recycled plastics in roads. Hence, some of the available plastomers—in pellet, flakes, or powder form—are coming from materials recycling facilities rather than chemical companies. This review article describes the details of using plastomers as bitumen modifiers—with a specific focus on recycled plastics—and how these can potentially be used to enhance bitumen performance and the road durability. Chemical modifiers for improving the compatibility between plastomers and bitumen are also addressed in this review. Plastomers, either individual or in combination of two or three polymers, are found to offer great stiffness at high temperature. Different polymers including HDPE, LDPE, LLDPE, MDPE, PP, PS, PET, EMA, and EVA have been successfully employed for bitumen modification. However, each of them has its own merit and demerit as thoroughly discussed in the paper. The recent push in using recycled materials in roads has brought new light to the use of virgin and recycled plastomers for bitumen modification as a low-cost and somehow environmental beneficial solution for roads and pavements.

Sustainable Polymers from Recycled Waste Plastics and Their Virgin Counterparts as Bitumen Modifiers: A Comprehensive Review.

Systematic literature review, meta-analysis and artificial neural network modelling of plastic waste addition to bitumen

The quantity of plastics used throughout the world is increasing every year Municipal solid wastes (MSW), manufacturing processes and service industries produce a lot of waste plastic materials The increasing awareness among consumers about the environment has contributed to the concerns over disposal of generated wastes The growing number of plastic materials every year and limited landfill conditions causes many alternatives exist for the disposal of plastic waste This paper provides a summary of the study on the utilization of polyethylene terephthalate (PET) in road construction Data from researcher show that PET can improve some properties of modified asphalt mixture Having considered the economic and environmental prudent angles, utilization of PET as an additive to asphalt mixture is suitable to be used for road pavement

https://iopscience.iop.org/article/10.1088/1757-899X/203/1/012004/pdf

Utilization of Polyethylene Terephthalate (PET) in Asphalt Pavement: A Review

Plastic bottle for recycling can be found from the household waste stream, and most of them are made from Polyethylene Terephthalate. In this research, PET is utilized to explore the potential prospects to upgrade asphalt mixture properties. The objectives include deciding the best measure of PET to be used. For experimental, Marshall mix design was utilized to determine the ideal bitumen binder content and to test the modified mixture properties. The samples were created per the requirement for aggregate course wearing (ACW14) using the Standard Specification of Road Work (SSRW) in Malaysia. 20 samples were utilized to determine the binder content, and 30 samples were used to research the impact of modifying asphalt mixtures. 2%, 5%, 10%, 15% and 20% of PET by weight of the optimum binder content (4.8%) were tested. Optimum PET content is 10%, and the result shows a good stability with 16.824kN, 2.32g/cm3 bulk density, void filled with bitumen (VFB) with 71.35%, flow with 3.2248mm, air void (AV) with 4.53%, and void of mineral aggregate (VMA) with 15.15%. The outcomes showed that PET modifier gives better engineering properties. Therefore, 10% of PET by the weight of binder content was suggested as the best amount of the modifier.

https://iopscience.iop.org/article/10.1088/1757-899X/203/1/012005/pdf

Utilization of polyethylene terephthalate (PET) in bituminous mixture for improved performance of roads

Rapid growth of plastics industries in Asia's emerging markets particularly in Malaysia, in one way, it raised expectations for everyday comforts, in the other way it also causes environmental issues. Plastic bottle for recycling can be found from the household waste stream, and most of them are made from Polyethylene Terephthalate (PET). Recycling this plastic into another form might be one of the cheapest and rapid solutions. However, turning this plastic into some other usable form uses energy and this may not become a green waste management solution. In this research, PET is utilized to explore its potential prospects to upgrade asphalt mixture properties. This study investigates the use of waste plastic as modifier for aggregates (plastic coating aggregate). The type of plastic used in this study was waste PET plastic bottle. The shredded waste PET plastic (size 0.075mm to 1.18mm) was mixed with hot aggregate to form a thin layer on the surface of the aggregates. The properties of modified aggregate and unmodified aggregate was tested and compared. 1% and 2% of plastic by weight of aggregate were used to coat the aggregate. The plastic-coated aggregates are tested for impact value and crushing value. The test results had demonstrated that there was an improvement in the properties of plastic coated aggregates.

https://iopscience.iop.org/article/10.1088/1757-899X/469/1/012056/pdf

Effect of waste polyethylene terephthalate (PET) on properties of road aggregate

Polyethylene Terephthalate (PET) and latex belong to the family of the polymer. PET type of plastic bottle is the most commonly found in the household waste stream. Recycling this type of plastic into another form is the cheapest and the best way of recycling. However, this may not become a green waste management solution when energy is used to transform this plastic into another useable form. In this study, PET was used to discover the potential for improvement of asphalt mixture properties. This study examines the plastic waste used as an aggregate coating. PET plastic bottle was shredded and sieved to obtain size 0.425 to 0.075mm then was blended with hot aggregate to form a thin layer of plastic coating on the aggregate surface. The comparison between unmodified aggregate properties and modified properties was studied. 1%, 3%, 5%, 7%, 9%, 11%, 13% and 15% of plastic by weight of aggregate were used as aggregate coating. The aggregate impact value test (AIV) and aggregate crushing value test (ACV) were done on the plastic coated aggregate. The test result had shown an improvement in the properties of plastic coated aggregate. From the experiment results conducted on the PET and aggregate, we can conclude that the lowest percent of aggregate loss on the crushing value test is 16.34% when PET content is 9% while 8.00% when PET content is 13% for the impact value test. The lowest percent of aggregate loss for impact value is then compared with the percent loss of PET Latex coated aggregate. The presence of latex and PET has caused the strength of the aggregate to increase where the percentage loss value when performed impact test is very low that is can achieve 3.48%. The quality of flexible pavement can be improved when the surface of the aggregate is coated with the polymer.

Influence of polymer coated aggregate on the aggregate impact and crushing value

It is expected that with the miniaturization of materials being processed, energy consumption is also being ‘miniaturized’ proportionally. The focus of this study was to design a low energy micro-sheet-forming machine for thin sheet metal application and fabricate a low direct current powered micro-sheet-forming machine. A prototype of low energy system for a micro-sheet-forming machine which includes mechanical and electronic elements was developed. The machine was tested for its performance in terms of natural frequency, punching forces, punching speed and capability, energy consumption (single punch and frequency-time based). Based on the experiments, the machine can do 600 stroke per minute and the process is unaffected by the machine's natural frequency. It was also found that sub-Joule of power was required for a single stroke of punching/blanking process. Up to 100micron thick carbon steel shim was successfully tested and punched. It concludes that low power forming machine is feasible to be develo...

A. F. Ahmad

Papers

Utilization of Polyethylene Terephthalate (PET) in Asphalt Pavement: A Review

Utilization of polyethylene terephthalate (PET) in bituminous mixture for improved performance of roads

Effect of waste polyethylene terephthalate (PET) on properties of road aggregate

Influence of polymer coated aggregate on the aggregate impact and crushing value

Development of a low energy micro sheet forming machine