Low-density Polyethylene Waste Research Articles

Upcycling linear low-density polyethylene waste to turbostratic graphene for high mass loading supercapacitors

Linear low-density polyethylene (LLDPE) waste is difficult to upcycle into more valuable carbon materials because it tends to completely decompose into small molecules during thermal processing. In this work, LLDPE is upcycled into a high quality turbostratic graphene using a pre-treatment step to oxidatively crosslink the polymer with the assistance of solid additives (KCl and K2CO3) that improve crosslinking by increasing the effective surface area of the polymer melt during processing. After this pretreatment step, the crosslinked polymer could then be carbonized and catalytically graphenized between 400–950 °C without decomposition of the polymer feedstock. The LLDPE derived graphene (LLDPE-G) obtained from this process has a Brunauer–Emmett–Teller (BET) specific surface area, up to 1800 m2 g−1 and average Raman ID/IG and I2D/IG ratios of 0.85 and 0.57, respectively, indicating high quality graphene. When used as an electrode material in symmetric supercapacitors, LLDPE-G possesses a specific capacitance up to 175 Fg−1 at a mass loading of 20 mgcm−2, which is two times the commercial requirement, yielding an areal capacitance of 3.5 Fcm−2. Moreover, LLDPE-G exhibits exceptional cycling stability with a capacitance retention of 95.8 % after 100,000 cycles at a current density of 4.0 Ag−1. Additionally, the KCl and K2CO3 solids are recycled and reused over 3 complete reaction cycles to make new LLDPE-G with the material quality and electrocapacitive performance retained and verified after each cycle. Our approach creates new opportunities for upcycling waste LLDPE and other varieties of polyethylene into a higher value graphene used for electrochemical energy storage applications.

Eco-economic analysis of utilizing high volumes of recycled plastic and rubber waste for green pavements: A comparative life cycle analysis

The strategic repurposing of substantial volumes of plastic waste and end-of-life tires into asphalt pavement presents a compelling practical solution to the growing waste accumulation problem. Adopting a comparative LCA and LCCA approach, this study focuses on the environmental, functional, and economic performance of hot mixed asphalt (HMA) produced with various compositions to determine the most sustainable solution in the local context. The compositions included unmodified, styrene butadiene styrene (PMB), and the novel recycled composite produced with devulcanized rubber and waste low-density polyethylene (DVR + LDPE composite) HMAs. Research findings indicate that HMA modified with DVR + LDPE composite outcompete the traditional counterparts by significantly reducing GHG emissions by 54.5 % and 14.4 % compared to unmodified and PMB HMAs, respectively. The same can be extended to the cost analysis. The discussion emphasizes the practicality and significance of the novel waste composite and stresses adopting a complete life cycle perspective for asphalt sustainability assessment.

Downcycled neat LDPE plastic wastes fuelled CI engine’s carbon and soot emission reduction with an elevated performance by Acetylene (HC[tbnd]CH) premixed combustion

Wastes are not useless, but they are used less. Wastes can be reduced by utilization not by destroying. The unobserved single-used low-density polyethylene (LDPE) plastic wastes are the sources that produce the fuel energy for the CI engines by pyrolysis. This downcycles the LDPE wastes. This neat LDPE plastic waste pyrolysis oil (LPWPO) has lower performance and slightly higher carbon emissions than diesel. To rectify this challenge, a premixed charge of air–acetylene is inducted into a 1500 rpm 5.2 kW CI engine at 1–4 lpm of flow rate. Acetylene is admitted into the inlet manifold to vary the mixture strength. Up to 26 % of acetylene energy share is involved in the premixed combustion with LPWPO. At full load,4 lpm of acetylene induction with LPWPO oil produced 14.05 %, and 22.96 % increased BTE, and peak pressure than neat LPWPO respectively. At the same condition have 61.35 %, 87.5 %, 31.84 %, 22.64 % percentage reduction in soot (7.11 g/kWh), CO (3.71 g/kWh), UHC (0.18 g/kWh), and CO2 (732.1 g/kWh) emission than neat LPWPO respectively. However, the increased peak pressure increases the NOx emission. Therefore, Acetylene (4 lpm) induction with LPWPO is recommended for improved performance with reduced carbon and soot emissions. This method supports the LPWPO oil use in CI engines and indirectly supports the downcycling of single-use LDPE plastic waste in the environment.

Fused deposition modeling of polyethylene (PE): Printability assessment for low-density polyethylene and polystyrene blends

There is a global emphasis on recycling and reuse of plastic waste. Despite constituting over one-third of the world's annual plastic production, only 10 % of polyethylene is recycled. This study explores the use of fused deposition modeling (FDM) to enable the recycling of industrial waste of low-density polyethylene (LDPE) blended with expanded polystyrene (EPS). Two LDPE/EPS ratios (50/50 and 70/30) were investigated, and two types of styrene-ethylene-butylene-styrene (SEBS) rubber were incorporated as compatibilizers. The mechanical, rheological, thermal, and morphological properties of these blends were analyzed to assess their printability. Results indicate that the use of SEBS enhances the mechanical properties, thermal stability, and morphological uniformity of the blends. Particularly, malleated SEBS exhibited superior compatibilizing ability, fostering strong interactions at the LDPE/EPS interface. The best blend, based on printability assessments, was the 50/50 LDPE/EPS ratio with a 5 wt% malleated SEBS. Consequently, this blend was extruded into feedstock filaments, and it was successfully printed via FDM. The proposed blends are anticipated to perform effectively in various applications and serve as a foundation for future development of wear-resistant materials. The outcomes of this study present a novel approach for upcycling LDPE waste while promoting sustainable FDM practices.

Recovering Low-Density Polyethylene Waste for Gypsum Board Production: A Mechanical and Hygrothermal Study.

In recent decades, plastic waste management has become one of the main environmental challenges for today's society. The excessive consumption of so-called single-use plastics causes continuous damage to ecosystems, and it is necessary to find alternatives to recycle these products. In this work, a mechanical and hygrothermal characterisation of novel plaster composites incorporating LDPE waste in their interior was carried out. Thus, prefabricated plasterboards have been designed with a partial replacement of the original raw material with recycled LDPE in percentages of 5-10-15% by volume. The results show how these new composites exceeded the 0.18 kN minimum breaking load in panels in all cases, while decreases in density and thermal conductivity of up to 15% and 21%, respectively, were obtained. In addition, an increase of 3.8%in thermal resistance was obtained by incorporating these new gypsum boards in lightweight façade walls through simulations. In this way, a new pathway was explored for the recovery of these wastes and their subsequent application in the construction sector.

Waste plastics upcycled for high-efficiency H2O2 production and lithium recovery via Ni-Co/carbon nanotubes composites

The disposal and management of waste lithium-ion batteries (LIBs) and low-density polyethylene (LDPE) plastics pose significant environmental challenges. Here we show a synergistic pyrolysis approach that employs spent lithium transition metal oxides and waste LDPE plastics in one sealed reactor to achieve the separation of Li and transition metal. Additionally, we demonstrate the preparation of nanoscale NiCo alloy@carbon nanotubes (CNTs) through co-pyrolysis of LiNi0.6Co0.2Mn0.2O2 and LDPE. The NiCo alloy@CNTs exhibits excellent catalytic activity (Eonset = ~0.85 V) and the selectivity (~90%) for H2O2 production through the electrochemical reduction of oxygen. This can be attributed to the NiCo nanoalloy core and the presence of CNTs with abundant oxygen-containing functional groups (e.g., –COOH and C–O–C), as confirmed by density function theory calculations. Overall, this work presents a straightforward and green approach for valorizing and upcycling various waste LIBs and LDPE plastics.

Thermochemical Valorization of Plastic Waste Containing Low Density Polyethylene, Polyvinyl Chloride and Polyvinyl Butyral into Thermal and Fuel Energy

Pyrolysis is a promising technology for transforming waste plastics (WPs) into high-value products. In the near future it will play a key role in the circular economy, as a sustainable and environmentally friendly method of managing this waste. Although the literature reports on the pyrolysis of plastics, it is focused on pure polymers. On the other hand, the state-of-the-art knowledge about the pyrolysis of mixed and contaminated WPs is still scarce. Industrial waste processing usually uses polymer mixtures containing various impurities that influence the pyrolysis process during chemical WPs recycling. In the paper the pyrolysis of three types of WPs: low density polyethylene (LDPE), polyvinyl chloride (PVC) and polyvinyl butyral (PVB) from repeated mechanical recycling of plastics, as well as their binary and ternary mixtures, is considered. The influence of particular components on the pyrolysis process is analyzed. The aim is to determine synergistic behavior of the mixtures during the pyrolysis process, which is important for increasing the efficiency and quality of the obtained bioproducts. Methods such as thermogravimetric (TG/DTG) analysis coupled with Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy (MS) are used. The variations in the initial and final temperature of pyrolysis, mass loss and mass loss rate are determined. The content of PVC significantly lowers the initial temperature and mass loss and increases the final temperature. The pyrolysis of the considered mixtures shows a noticeable synergism—in the initial stage of pyrolysis up to a temperature around 450 °C, the mass loss is accelerated compared to what is predicted by simple superposition. The inhomogeneity of the mixtures as well as the waste origin causes a significant variation in the activation energy. Three main conclusions are obtained: (i) if the waste does not contain PVC, the pyrolysis is nearly complete at a temperature around 500 °C at a heating rate of 10 °C/min, whereas PVC is not fully processed even at 995 °C; (ii) the synergistic effects affect significantly the pyrolysis process by accelerating some steps and lowering the activation energy; and (iii) the presence of PVC noticeably lowers the temperature of the first stage of PVB pyrolysis. The investigation results prove that chemical recycling of mixed LDPE, PVC and PVB waste can be an effective method of plastic waste management.

Innovative Ex-Situ catalyst bed integration for LDPE plastic Pyrolysis: A thermodynamically closed system approach

The recycling of Low-Density Polyethylene (LDPE) poses a significant challenge due to its resistance to degradation and presence of impurities among the waste LDPE. This study introduces an innovative method for LDPE pyrolysis, aiming to enhance the efficiency of LDPE recycling and contribute to the circular economy of plastics. We utilized an HZSM-5 catalyst within a unique setup that incorporates a catalyst bed constructed from a quartz fibre membrane filter. This innovative hybrid method, a combination of in-situ and ex-situ modes, was designed to shield the catalyst from direct contact with undesired materials, thereby facilitating easy catalyst separation at the end of the process. Experiments were conducted in a high-pressure batch reactor, heated to 400 °C within a closed thermodynamic system. Parallel runs were performed for both pure and waste LDPE, with and without the catalyst. The catalytic pyrolysis resulted in an oil output of 40.3 % for waste LDPE and 43.5 % for pure LDPE, with a significant increase in aromatics when comparing thermal to catalytic pyrolysis. The calorific values of the pyrolysis liquids were found to be 46.2 for pure LDPE and 46.1 for waste LDPE, indicating their potential for sustainable hydrocarbon fuel synthesis. Following the catalytic pyrolysis, the spent catalyst underwent stepwise oxidation as a regeneration method, indicating a partial loss of activity but a similar influence on the degradation temperature as the fresh catalyst. This study not only presents a promising approach to LDPE recycling but also offers a comprehensive analysis of both the pyrolysis outputs and the spent catalyst. Such detailed analysis is crucial for refining the LDPE pyrolysis process and facilitating its scale-up for industrial applications.

Co-pyrolysis of plastic waste and eucalyptus waste wood for fuel pellets production: A study of fuel, mechanical, and combustion characteristics under varying binder proportion

The study explores the effect of varying molasses proportions as a binder on the characteristics of densified char obtained through the slow co-pyrolysis of plastic waste and Eucalyptus wood waste (Waste low-density polyethylene – Eucalyptus wood (WLDPE–EW) and Waste Polystyrene – Eucalyptus wood (WPS–EW)). Pyrolysis was conducted at 500 °C with a residence time of 120 min, employing plastic to wood waste ratios of 1:2 and 1:3 (w/w). The focus was on how varying the proportion of molasses (10–30 %), influences the physical and combustion properties of the resulting biofuel pellets. Our findings reveal that the calorific value of the pellets decreased from 28.94 to 27.44 MJ/Kg as the molasses content increased. However, this decrease in calorific value was compensated by an increase in pellet mass density, which led to a higher energy density overall. This phenomenon was attributed to the formation of solid bridges between particles, facilitated by molasses, effectively decreasing particle spacing. The structural integrity of the pellets, as measured by the impact resistance index, improved significantly (43–47 %) with the addition of molasses. However, a significant change in the combustion characteristics depicted by lower ignition and burnout temperatures were observed due to decrease in fixed carbon value and increase in volatile matter content, as the proportion of molasses increased. Despite these changes, the pellets demonstrated a stable combustion profile, suggesting that molasses are an effective binder for producing biofuel pellets through the densification of char derived from the co-pyrolysis of plastic and Eucalyptus wood waste. The optimized molasses concentration analyzed through multifactor regression analysis was 16.96 % with 28 % WLDPE proportion to produce WLDPE–EW char pellets. This study highlights the potential of using molasses as a sustainable binder to enhance the mechanical and combustion properties of biofuel pellets, offering a viable pathway for the valorization of waste materials.

Investigation of waste LDPE with Pongamia pinnata seed for sustainable resource recovery: Thermodynamics, Kinetics and artificial neural network modeling for co-pyrolysis potential

Pyrolysis conversion offers the advantages of significant waste reduction and potential energy recovery. This work examined the potential of combining plastic and agricultural wastes as pyrolysis feedstocks. The mixture of waste low-density polyethylene and Pongamia pinnata seeds was analysed using differential and thermogravimetric methods. In addition to the Coats-Redfern (CR) method, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Friedman (FRM), and Kissinger (KN) model-free methods were also applied to calculate the kinetic parameters. The apparent activation energy (Ea) calculation demonstrated that the co-pyrolysis conversion required Ea values of 125–154 kJ mol−1. The artificial neural network (ANN) model was considered to validate thermogravimetric data. The R2 values were near unity in training, validation, and testing conditions, with the minimum possible value for mean square error obtained for the considered heating rates. The Pongamia pinnata seeds and waste plastic mixture could surely be utilized to lessen environmental degradation, add value to leftover seeds and waste low-density polyethylene by extracting fuel for transportation and other commercial activities, and produce industrial chemicals, as found through the kinetic modelling, thermodynamic parameters, and ANN modelling.

Utilization of recycled concrete aggregates in LDPE-bonded cementless paver blocks

This study investigates the utilization of recycled concrete aggregates (RCA) in waste low-density polyethylene (LDPE)-bonded, non-traffic cementless paver blocks. RCA is incorporated at varying percentages (0%, 25%, 50%, 75%, and 100%) to replace virgin coarse aggregates. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and melt flow index (MFI) were performed to characterize the thermal and physical properties of LDPE. RCA was treated using a 2-phase treatment technique to incorporate its efficient utilization. Four types of LDPE-to-aggregate mixes, namely, A (1:2.5), B (1:3), C (1:3.5), and D (1:4), were prepared to determine the optimal ratio and the quality control parameters through trial mixes. Paver blocks were evaluated based on their compressive strength, density, water absorption, and thermal strength stability. The results indicate that performing a double-treatment on RCA, optimized mix ratios, and identifying quality control parameters enhances the overall performance of paver blocks. A 35 MPa strength is achieved with 75% replacement, 1:3.5 LDPE-to-aggregate ratio, 30:70 coarse to fine aggregate ratio, and 50 mm depth, with a melt mixing temperature of 180–210°C. Microstructure analysis reveals a strong inter-transition zone (ITZ) for 75% replacement. The ANOVA, followed by a post-hoc analysis, was performed to validate the significance of these results.

Comparative Analysis of Kerosene Grade Fuel from Pyrolysis of HDPE and LDPE Waste Plastics

To curb the menace of plastic waste and energy crisis, this study investigated the conversion of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) grades of plastics to kerosene. Plastics sourced from dumpsites within Port Harcourt metropolis in Rivers State, Nigeria were shredded and pyrolyzed (thermally degraded under inert condition at a temperature range of 350-400oC). The obtained hydrocarbon liquid was distilled using distillation column at a temperature range of 150-270oC and characterised to evaluate the physico-chemical parameters such as flash point, density, copper corrosion, and calorific value and compared against the acceptable standard. The result showed that these properties were within the permissible limit. However, the sulphur content and smoke point of HDPE and LDPE were above and below the limits, respectively. The GC-MS and GC-FID results of kerosene samples obtained from both grades of plastics indicates that the product comprised C9 to C17 grades.

Laboratory investigation on the properties of warm mixing-recycled asphalt containing waste oil and plastics

ABSTRACT The integration of warm-mix and regeneration technologies is gaining momentum due to its dual advantages: enhancing the utilization of recycled asphalt and promoting environmental sustainability. In this study, these technologies by leveraging waste materials were synergized. Specifically, kitchen waste oil underwent chemical treatment to serve as a rejuvenator, while waste low-density polyethylene was transformed into pyrolysis wax, a beneficial additive for the asphalt mix. Utilizing these waste components, a sustainable warm mixing-recycled asphalt blend was formulated. This blend’s efficacy was meticulously evaluated through viscosity tests, rheological assessments, four-component analyses, and FT-IR evaluations. Optimal results emerged when incorporating 5% waste pyrolysis wax and 3.3% waste oil into warm recycled asphalt, notably improving viscosity reduction, high-temperature performance, rutting resistance, and fatigue life at 25 °C. Moreover, the four-component test shows the component of aged asphalt after adding the optimal combination is basically consistent with that of the neat asphalt. Importantly, FT-IR tests affirmed that pyrolysis wax bolstered the blend’s oxidation resistance. Through gray correlation analysis, we deduced that asphalt’s component changes are intricately linked with rheological property variations. Notably, the carbonyl index exhibited a pronounced negative correlation with rutting and fatigue life.

3D Oleophilic Sorbent Films Based on Recycled Low-Density Polyethylene.

Recycling low-end, one-time-use plastics-such as low-density polyethylene (LDPE)-is of paramount importance to combat plastic pollution and promote sustainability in the modern green economy. This study valorizes LDPE waste by transforming it into 3D oleophilic swellable thin films through a process involving dissolution, phase separation, and extraction. These films are subsequently layered using a customized polypropylene (PP) based nonwoven fabric separator and securely sealed in a zigzag pattern. The zigzag-shaped seal enhances the adhesion of pollutants to the sorbent by providing wire curvatures that increase retention time and uptake capacity. As a result, the sorbent exhibits impressive oil uptake capacities, with immediate and equilibrium values of 120 g/g and 85 g/g, respectively. Notably, the as-prepared sorbent demonstrates low water retention and high selectivity for oil, outperforming commercially available oil sorbents. The unique design involving a 3D-film structure, superposed films, and a zigzag-shaped seal offers a sustainable and value-added solution to the issues of LDPE waste and oil spills on water surfaces.

Pengaruh Penggunaan Limbah Plastik LDPE sebagai Modifikator Campuran AC-WC

In recent years, the increasing amount of plastic waste in many cities in developing countries, including Kupang City, has become a serious environmental problem. The use of plastic waste as a pavement material is one solution to deal with the problem of plastic waste. One type of plastic that can be used as an asphalt mixture modification material is Low Density Polyethylene (LDPE). This research aims to determine the use of LDPE plastic waste modified with AC-WC (Asphalt Concrete-Wearing Course). Five variations of AC-WC mixture were made based on LDPE plastic waste content of 6, 7, 8, 9, 10% based on optimum bitumen content (OBC). Marshall test method was used to determine the OBC and to evaluate the marshall characteristics of LDPE modified AC-WC. The OBC of conventional AC-WC was found to be 5.23% by weight of total aggregate while the ptimum plastic modified bitumen content (OPMBC) of LDPE modified AC-WC was 7.45% by weight of OBC. AC-WC modified with 7.45% LDPE waste had 47.98% higher OPMBC compared to conventional AC-WC

Eco-synthesis, characterization and application of waste plastics pyrolysis char in arsenic removal from contaminated water: An integrated circular framework with parametric response surface methodology optimization-cum-artificial neural network model

Eco-synthesis of a novel, cost-effective activated adsorbent from waste low-density polyethylene plastic pyrolysis char at 550 °C and its arsenic adsorption potential in simulated aqueous media has been investigated. Characterization reveals good surface chemistry and evolved morphology of activated char adsorbent with carbon structures at high pyrolysis temperature, thereby facilitating high arsenic adsorption uptake. A unique integrated framework of kinetic equilibrium investigation, parametric optimization applying response surface methodology (RSM) with responsive arsenic adsorption efficiency and artificial neural network (ANN) model for response validation has been presented. There is reasonably good fitting of experimental equilibrium figures into the Langmuir isotherm model (R2 = 0.9920). The effects of adsorbent pyrochar dose, arsenic concentration, contact time and pH on the arsenic removal capacity have been depicted via conjugate RSM graphs. The ANN regression curves showed R2 value of 0.99436, validating the model with ANN architecture as 4–8-1. Iron oxide complexation with arsenic on adsorbent surface is reported to play a dominant role in the proposed adsorption mechanism. The proposed hybridized model can be applied to examine the adsorptive removal of various contaminants in water. Techno-economic analysis of scaled-up community arsenic filter showed high removal efficiency (> 90%) of arsenic by activated plastic pyro-char adsorbent from contaminated water at an affordable cost of 0.67 $/m3 of treated water. The activated plastic waste pyro-char with an adsorption capacity of 7.21 mg/g is, therefore, environmentally sustainable in plastic waste management in the post-pandemic era for a ‘waste to wealth’ circular economy with perspective arsenic removal from contaminated water.

Catalytic pyrolysis of waste high-density (HDPE) and low-density polyethylene (LDPE) to produce liquid hydrocarbon using silica-alumina catalyst

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% wax-like hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GC-MS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. J. Bangladesh Acad. Sci. 47(2); 195-203: December 2023

Utilization of fuel energy from single-use Low-density polyethylene plastic waste on CI engine with hydrogen enrichment – An experimental study

An effective strategy to reduce global waste is to convert the waste into Energy effectively. Single-use Low-density polyethylene (LDPE) plastic waste poses an environmental challenge by slower decomposition. Pyrolysis is one of the best techniques for converting waste plastics into Waste Low-density polyethylene pyrolysis oil (WLPO), a useful energy source similar to diesel. Operating an engine directly with neat WLPO lowers the performance and increases carbon monoxide, unburnt hydrocarbons, and smoke emissions than diesel. Hence, to enhance the performance and emission characteristics of the engine operating with WLPO dual fuel mode, different flow rates of hydrogen induction from 3 to 12 lpm were studied. The results were compared with diesel and neat WLPO. 12 lpm of hydrogen induction shares 15.19 % of hydrogen energy in combustion for WLPO. Compared to neat WLPO, 12 lpm hydrogen induction has a percentage increase of 22.89 in brake thermal efficiency, 15.88 in peak pressure, 60.85 in heat release rate, and 61.46 in Nitrogen oxides, as well as a percentage decrease of 53.42 in smoke, 48.94 in carbon dioxide, 53.99 in unburnt hydrocarbons, and 86.86 in carbon monoxide. Also, these are all similar to and better than the neat diesel operation except for the NOx emission. The hydrogen induction with WLPO increases the engine performance and reduces the smoke and carbon emissions. This fuel usage with hydrogen in IC engines indirectly supports LDPE plastic waste reduction by utilization and reduces objectionable emissions.

Plastic Waste Sheets Effects on Reclaimed Asphalt Pavement Performances

Abstract This paper aims to examine physical and mechanical performances of a Reclaimed asphalt pavement (RAP) material reinforced with 5 to 15 mm size sheets of plastic waste. The three types of plastic used in the study are: low density polyethylene (LDPE), high density polyethylene (HDPE) and polyethylene terephthalate (PET) with 1%, 1.5%, and 2% dosage by weight of aggregates. Obtained Duriez test results testify to a 9% to 30% improvement in moisture resistance for all types of plastic compared to virgin mixture while for LDPE waste plastic type workability test attests an acceptable compaction condition for RAP material with less than 1.5% of waste plastic. Nevertheless, it has been noticed an increase in void index and compaction difficulties starting from 1.5% dosage, resistance to rutting has also improved with the addition of waste plastic, an improvement in fatigue strength was also observed particularly at 2% dosage.

Characterisation of new sustainable gypsum composites with low-density polyethylene waste from single-use bags

The main objective of this research is to determine the feasibility of using Low-Density Polyethylene (LDPE) waste as secondary raw material in the production of new eco-friendly gypsum composites. For this purpose, LDPE waste in crumb form has been incorporated as a partial replacement by weight of the plaster material powder at percentages of 1%, 2% and 3%. Additionally, the gypsum binder in traditional gypsum composites has been replaced for LDPE waste in granulated form, at percentages of 2.5%, 5.0% and 7.5%. The experimental campaign has involved a detailed physical and mechanical characterisation of the gypsum compounds produced to study their potential applications in the construction sector. The results show that more efficient materials are obtained with the addition of these plastic wastes, significantly reducing bulk density and thermal conductivity coefficient compared to traditional gypsum-based materials. Additionally, a considerable reduction in capillary water absorption coefficient and open porosity has been observed. Moreover, the mechanical strengths in flexion and compression surpassed the limits established by current regulations for all the prepared mixtures. In this way, these innovative gypsum composite materials can be useful for application in the production of prefabricated elements, promoting the reincorporation of these plastic wastes, which currently present a challenge from the perspective of sustainability and circular economy.