Plastic Aggregates Research Articles

Assessing the Viability of Waste Plastic Aggregate in Stone-Modified Asphalt Concrete Mix for Bus Rapid Transit Pavement Maintenance

This research takes on a scientific problem originating from the pervasive deterioration observed in the pavements of Bus Rapid Transit (BRT) systems, which presents formidable challenges to their durability and imposes significant financial burdens on BRT organizations. While wear and tear on BRT pavements is a widely recognized concern, there exists a pronounced deficiency in sustainable solutions to address this issue comprehensively. This study endeavored to bridge this scientific gap by exploring the option of incorporating waste plastic aggregate (WPA) and recycled asphalt pavement (RAP) into the pavement material. The series of comprehensive investigations commenced with an assessment of modified binders. We identified a 25% extracted RAP binder as the most suitable candidate. Our research next determined that a 4% WPA content offers optimal results when used as an aggregate replacement in a stone-modified asphalt concrete mix, which is further refined with a 13 mm nominal maximum aggregate size (NMAS) gradation, resulting in superior performance. Under double-load conditions of the Hamburg Wheel Tracking test, rutting in the 10 mm NMAS mixture rapidly increased to 9 mm after 12,400 HWT cycles, while the 13 mm NMAS mixture showed a more gradual ascent to the same critical rutting level after 20,000 HWT cycles (a 61% increase). Real-world application at a designated BRT station area in Seoul reinforced the findings, revealing that the use of 13 mm NMAS with 4% WPA and RAP significantly improved performance, reducing rutting to 75 µm and enhancing pavement resilience. This configuration increased Road Bearing Capacity (RBC) to 5400 MPa at the center zone, showcasing superior load-bearing capability. Conversely, the 10 mm NMAS mixture without RAP and WPA experienced severe rutting (220 µm) and a 76% reduction in RBC to 1300 MPa, indicating diminished pavement durability. In general, this research highlights the need for innovative solutions to address BRT pavement maintenance challenges and offers a novel, environmentally friendly, and high-performance alternative to traditional methods.

Mechanical and Thermal Effects of Using Fine Recycled PET Aggregates in Common Screeds

The increasing consumption of plastics has necessitated the need to find a sustainable solution to reuse PET within common building materials. Recycled PET reinforcement would reduce plastic waste that is difficult to dispose of and CO2 emissions, representing a sustainable solution for generating lighter building materials. The goal of this work was to define a new cementitious mixture design and to study the mechanical and thermal behavior of three typologies of screeds with fine recycled polyethylene terephthalate (PET) aggregates. A weight percentage of PET of 1%, 2%, and 3% was used. The test results for sustainable screeds (S-Screeds) with waste PET were compared with a reference screed without the addition of plastic. In the fresh state, the workability and the air content were measured, while in the hardened state, the density, thermal conductivity, and compressive and flexural strength were investigated. These properties showed improvement for some tested S-Screeds after the introduction of fine (a few millimeters in size) and irregularly shaped waste plastic aggregates. Scanning electron microscopy (SEM) analysis showed the presence of a release surface between the cementitious mixtures and the plastic material, even if the mechanical interaction between the matrix and PET still existed.

Evaluation of eco-friendly asphalt mixtures incorporating waste plastic aggregates and additives: Magnesium, fly ash, and steel slag

This research explores the applicability of waste plastic aggregate (WPA) in the development of environmentally friendly asphalt mixtures, contributing to resource conservation, waste recycling, and the prevention of environmental issues associated with landfilling and incineration. Through experimental analysis of durability and common characteristics, the research investigates the optimal asphalt content (OAC) for practical implementation, particularly in substituting natural aggregates with waste plastic aggregates in asphalt mixture production. It examines the feasibility of producing asphalt mixtures by incorporating WPA and focuses on preventing microplastic generation using WPA in lower pavement layers. Additive materials, including Magnesium, fly ash, and steel slag powder, were used to enhance the properties of the mixtures. The experimental variation ratios in this research were assessed through a meticulous mixture design process involving the incorporation of WPA at varying contents (0%, 3%, 5%, 7%, and 10%) in both base (BB-2) and middle (MC-1) asphalt layers, enabling a comprehensive evaluation of the performance and characteristics of the resulting asphalt mixtures in comparison to control mixtures. Various tests, including wheel tracking, deformation strength, dynamic stability, crack resistance, and water resistance, are conducted to evaluate the performance of the mixtures. The findings indicate that 5% WPA can be seamlessly integrated into the asphalt mixture without external issues, and it exhibits satisfactory performance during the manufacturing process. The utilization of waste plastic fine aggregate results in non-uniform voids, while mixtures with 7% WPA fail to meet water resistance requirements. Coarse aggregates show better resistance to plastic deformation than fine aggregates, and mixtures with 5% WPA incorporating waste plastic fine aggregate demonstrate the highest resistance. Overall, this research provides valuable insights into the utilization of waste plastic aggregate in asphalt mixtures, highlighting its potential to enhance sustainability and pave the way for resource-saving practices in road construction, with the use of additive materials further improving the mixture properties.

Waste Plastic Induced in Self Compacting Concrete to Avoid Plastic Pollution

Abstract: In this present study the plastic aggregate obtained from E-waste is used as a partial replacement of coarse aggregate in self-compacting concrete. An experimental investigation on the fresh, hardened characteristics of concrete using M40 grade of Self compacting concrete are carried out by casting standard concrete with various volume fractions of plastic aggregate such as 0%, 10%, 20%, 30%, 40%, 50% to determine optimal dosage. The fresh properties of SCC reveal that the workability of concrete are improved by using plastic aggregate. Strength properties such as compressive strength shows that up to 30% substitution of coarse aggregate there is no major change in compressive strength as compared to normal concrete. Beyond that there is drop in compressive strength for 50% replacement of coarse aggregate by plastic aggregate. Split tensile strength, Flexural strength and Young modulus of concrete increases for 10% plastic aggregate. Beyond that strength decreases upto 50% replacement. Impact strength decreases for all replacement levels.

Strength, durability, and impact behavior of recycled aggregate concrete with polypropylene aggregate

Massive consumption and production of plastic is expected to have a significant environmental impact in the near future. Plastic waste from landfills can be refined and recycled as aggregates in concrete through subsequent processing. Several studies have already been conducted using plastic scraps as aggregate in concrete. However, more research is needed before it can be incorporated into structural concrete. Therefore, this study aims to investigate the static and dynamic behavior of concrete made with polypropylene plastic aggregate (PPA) obtained from waste plastic materials. Natural coarse aggregate (NCA) and recycled concrete aggregate (RCA) are partially replaced with PPA in this study and drop impact tests are performed after the samples are exposed to room and elevated temperatures (200 °C and 400 °C). PPA replacement percentages are 0, 5, 10, and 15 %. The drop impact test is performed on both cylinders (150 mm × 63.5 mm) and beams (100 × 100 × 500 mm) specimens. Different mechanical and durability tests are also investigated. The impact energy decreases by up to 68 percent as the PPA percentage increases at room temperature. Furthermore, when the specimens are heated to 200 °C or 400 °C, the impact blows are significantly reduced (6–13 no). After being heated to 200 °C and 400 °C, the 15 percent NCA replaced cylinder loses 87 percent and 91 percent of its impact energy, respectively. In terms of mass loss, the control cylinder has a higher loss than the PPA cylinders, indicating that the presence of PPA in concrete causes less damage. In terms of mechanical properties, the 5 percent PPA-based concrete outperforms the control. Depending on the concrete age and coarse aggregate types, a 5 % PPA content increases compressive strength by up to 11.6 percent. In terms of durability, the water absorption tendency increases with increasing PPA content, and all-natural PP concrete (NPC) and recycled PP concrete (RPC) exhibit moderate to very low chloride ion penetrability. Overall, it is proposed that 5 % PPA be used with NCA and RCA for structural applications.

Influence of plastic aggregate geometry on strength properties of cement-stabilized macadam

In order to improve the toughness and flexibility of cement-stabilized macadam and inhibit crack formation and propagation, the influence of plastic aggregate geometry on the strength properties of cement-stabilized macadam is studied. The surface roughness of plastic aggregate was designed into Ra 12.5 and Ra 25. When the content of plastic coarse aggregate was gradually increased from 4 to 8%, 12%, 16%, 20%, and 24%, the compressive strength, splitting strength, and the tensile-compression ratio of the cement-stabilized macadam made of aggregate with rough surface texture were found higher than those of aggregate with smooth surface texture. The rough cylindrical, spherical, spindle, and dumbbell-shaped plastic coarse aggregates were designed and prepared for testing. The test results showed the maximum compressive strength, splitting strength, and tensile-compression ratio of cement-stabilized macadam with the dumbbell-shaped plastic coarse aggregate. The tensile-compression ratio increased by 15.2% compared to natural aggregate cement-stabilized macadam. The results show that under the same conditions, the plastic aggregate with different geometry can improve the compressive and splitting strengths of cement-stabilized macadam and significantly improve the toughness and flexibility, with dumbbell-shaped plastic coarse aggregate having the greatest improvement, especially compared with natural aggregate cement-stabilized crushed stone. This research provides insights for improving pavement engineering quality and new ideas for utilizing waste plastics.

Flexural and bond-slip responses of reinforced concrete beams containing recycled coarse aggregate and polypropylene plastic

Reusing non-biodegradable plastic waste and recycled concrete as a substitute for natural aggregates can help alleviate the pressure on natural resources. Therefore, this study aims to incorporate polypropylene plastic aggregate (PPA) and recycled coarse aggregate (RCA) in concrete mixtures. The PPA is used as a partial replacement of RCA in reinforced concrete (RC) beams. The flexural responses and bond behaviors of RCA based PPA concrete (RPC) beams are investigated. The main variables are PPA percentages (0, 5, and 10%) and shear span to effective depth ratios (a/d = 2.13, 1.52, 1.07). Nine 1100 mm long RC beams are fabricated for bending tests, and nine 350 mm long RC beams are cast for pull-out tests. Results indicate that the ultimate moment capacity is increased by up to 28.6% for 5% PPA content depending on the beam depths, and for 10% PPA content, it is decreased by up to 15%. Ductility and toughness are increased by up to 11.7% and 113.6%, depending on the PPA contents and beam depths. Bond strength is increased by up to 16.6% for 5% PPA content and then decreased for 10% PPA by up to 37.5% depending on different beam depths. It is recommended that 5% PPA be used in concrete to improve the overall performance of the RPC beams.

Engineering properties of geopolymer concrete composites incorporated recycled plastic aggregates modified with nano-silica

The novel approach of reusing recycled plastic in construction instead of landfilling has gained recognition. However, the inclusion of recycled plastic aggregates (RPA) tends to have a negative impact on various concrete properties. Previous studies have explored surface treatment techniques to mitigate these effects. Nevertheless, there is limited research on enhancing the properties of RPA geopolymer concrete (GPC) through the addition of nano-silica (NS) particles in to the GPC mixtures. This study aims to experimentally investigate the properties of GPC incorporating RPAs modified with NS particles. The experimental program consists of seventeen mixtures divided into three stages. In the first stage, the effect of NS addition on the performance of GPC mixtures was evaluated. Moreover, the effect of different percentages of RPAs was investigated in the second phase. In the third stage, the optimum percentage of NS particles found in the first stage was utilized to improve the performance of GPC mixtures which aggravated in the second stage. The total binder content for all mixtures was 450 kg/m3 which contained 90% of ground granulated blast furnace slag (GGBFS) and 10% silica fume. In the first stage the GGBFS was replaced by 1%, 2%, 3%, and 4% NS particles, while, in the second stage, the natural fine aggregate was replaced by RPAs at six volume fractions (5%, 10%, 20%, 30%, 40%, and 50%). The fresh behaviour of all GPC mixtures was investigated to assess the flowability, setting and cohesiveness of the mixtures. The mechanical behaviour was evaluated for compressive strength, splitting tensile strength, modulus of elasticity, flexural strength, and stress-strain behaviour. Moreover, the microstructure characteristics were investigated to illustrate the modifications that occurred in the microstructure scale. The results indicated that the addition of an optimum percentage of NS particles can significantly restore most properties of RPA-GPC which were degraded due to the addition of RPAs. This technique can help the construction industry to safely use the RPAs in the GPC mixtures without concern about their negative impact on concrete performance.

Mechanical performance of fiber-reinforced concrete and functionally graded concrete with natural and recycled aggregates

This study aims to assess the mechanical performance of functionally graded concrete (FGC) in comparison to conventional plain cement concrete (PCC) and fibre-reinforced concrete (FRC). For this purpose, five concrete mixes were prepared, defined in eleven patterns, including PCC as a control mix, two FRC mixes, and eight combinations for FGC mixes. The hooked-end steel fibres and recycled thin polyethylene terephthalate (PET) strips from used bottles were utilized as fibres in 0.75 % of the volume of the mix in the FRC and FGC mixes. The natural aggregates were replaced by 15 % by weight with recycled plastic aggregates (RPA) and recycled concrete aggregates (RCA) in the FGC mixes. The mechanical performance of all specimens was assessed by compressive, split tensile and flexural strength tests, whereas the concrete quality was evaluated by the ultrasonic pulse velocity (UPV) test. The results revealed that the FRC mix containing steel fibres has 50.6 % higher compressive strength, while PET-FRC exhibited 42.4 % lower strength than the PCC. The best combination of the FGC mix is RCA + SFRC (H), which showed 27.6 % more compressive strength than PCC. The steel fibre-reinforced concrete (SFRC) mix has the highest split tensile strength, which is 47.5 % higher than the PCC. The best combination of FGC mixes is SFRC + PET-FRC (J), yielding 29.3 % higher tensile strength than PCC. On the other hand, both fibres contribute to the flexural strength enhancement of FRC. The FGC mix (K) yielded the highest flexural strength, with PET-FRC and SFRC in the upper and bottom layers, respectively, giving 40 % more flexural strength than the PCC specimen. The UPV values depicted that fibres and recycled aggregates in FGC specimens enhanced the quality of concrete. The highest value of UPV was recorded in the mix PCC + SFRC (G) containing PCC and steel fibres, which almost reached the upper limit of the recommended UPV values.

Synergistic effects of recycled plastic aggregate and nano-silica on the elevated temperature and durability performance of self-compacting concrete

A new approach to reusing plastic waste in construction is by incorporating recycled plastic aggregates (RPA) in concrete. However, this technique negatively affects concrete properties. Previous studies have treated RPAs to mitigate this issue, but none have investigated enhancing the properties of self-compacting concrete (SCC) made with RPAs through the addition of nano-silica (NS) particles. This study aims to explore the properties of SCC with RPAs modified by NS. Sixteen mixtures were tested in three stages: evaluating the impact of NS on SCC performance, examining various RPA percentages, and using the optimal NS percentage to improve negatively affected SCC mixtures. NS particles replaced cement at 1%, 2%, and 3% in the first stage, while RPAs replaced natural fine aggregate (NFA) at fractions of 5%, 10%, 15%, 20%, 30%, and 40% in the second stage. Compressive strength was assessed over different periods and at elevated temperatures. Durability performance, including water absorption, acid attack, electrical resistivity, chloride permeability, and bulk electrical conductivity, was extensively studied. The results revealed that the addition of the optimal NS percentage effectively restored the most degraded properties of SCCs, making it a safe and effective technique for utilizing RPAs in SCC mixtures without compromising concrete performance.

Study on Correlations between Tailings Particle Size Distribution and Rheological Properties of Filling Slurries

The influence of the mass concentration and particle size distribution on rheological parameters and slump was investigated by analyzing the mixture of overflow tailings (OT) and classified tailings (CT). The correlation between the rheological parameters, slump and characteristic value of the tailings particle diameter was discussed. Finally, the ratio parameters of a mixed tailings filling slurry were optimized using a lead–zinc mine in Guangdong, China as the engineering background. The results showed a quadratic decrease in the slump of the tailings slurry as the mass concentration increased, while the slump decreased with a decreasing particle size. With the increase in the mass concentration, the yield stress of the tailings slurry follows a quadratic function, while the plastic viscosity exhibits linear growth. The influence of tailings fine particles on the sensitivity of the yield stress and plastic viscosity to the mass concentration is reduced as their content increases. The yield stress and plastic viscosity of the tailings slurry exhibit a quadratic function decrease and linear growth as the slump increases. The slump of the tailings slurry is related to the particle size characteristic value and the mass concentration of the slurry. The correlation coefficient between the yield stress and the aggregate characteristic particle size increases most obviously at d10~d50, and the increase in the characteristic particle size will enhance the correlation between the yield stress and particle gradation. The correlation coefficient between the plastic viscosity and aggregate particle gradation parameters exhibits an initial increase followed by stabilization with an increasing characteristic particle size, with the most significant increase observed at d10~d50.

Recycled aggregate blends for backfilling deep trenches in trafficable areas

Limited supplies of natural aggregates for backfilling pipeline trenches in trafficable areas have led to considering secondary resources. Utilizing blends entirely made of recycled aggregates to backfill excavated trenches in trafficable areas is rare if any, where traditionally, natural crushed rock has been used. In this study, 18 blends of various proportions of recycled glass (RG), plastic (RP), tire (RT), and concrete aggregate (RCA) were proposed and studied as alternatives. First, typical pavement tests such as compaction and CBR were carried out to select 7 suitable mix designs based on available backfill specifications. The shortlisted blends were further investigated through a specialized testing program, in particular, repeated load triaxial to simulate site stress levels. The results showed that CBR and resilient modulus characteristics improved by the increase in RCA content and the reduction in RT content. Three recycled material blends were selected as the optimum mix designs, and were next compared with the surrounding natural clay subgrades of the study area. The resilient modulus response of optimum mix designs exhibited up to 1.6 times greater stiffness compared to the clay subgrades under the same stress levels. The outcomes of this study reduce the demand for natural aggregates and promote the use of sustainable materials for backfilling pipeline trenches located under traffic loadings.

Feasibility of Sustainable Asphalt Concrete Materials Utilizing Waste Plastic Aggregate, Epoxy Resin, and Magnesium-Based Additive.

This research addresses the urgent need for sustainable and durable asphalt mixtures by quantitatively investigating the effects of incorporating waste plastic aggregate (WPA) and magnesium-based additives. This study explores WPA content levels of 3%, 5%, and 7% wt of aggregate in combination with a fixed 3% wt epoxy resin content to the asphalt binder, supplemented with the 1.5% wt magnesium-based additive. The novelty of this research lies in its comprehensive analysis of various performance parameters, including deformation strength, indirect tensile strength (ITS), rut depth, and dynamic stability, to assess the impact of WPA, epoxy resin, and the magnesium-based additive on asphalt mixture properties. The results demonstrate significant improvements in key performance aspects with increasing WPA content. The WPA mixtures exhibit enhanced deformation strength, with values of 4.01, 3.7, and 3.32 MPa for 3, 5, and 7% wt WPA content, respectively, compared to the control mixture. Furthermore, the inclusion of WPA and epoxy resin, along with the magnesium-based additive, contributes to improved adhesion, cohesion, and resistance to stripping damage. Notably, the 7% wt WPA mixture showcases exceptional performance, characterized by a final rut depth of 2.66 mm and a dynamic stability of 7519 passes per millimeter, highlighting its superior rutting resistance and load-bearing capacity. This study also reveals the influence of WPA content on ITS and stiffness properties, with the 5% wt WPA mixture achieving an optimal balance between strength and stiffness. Overall, this research highlights the potential of incorporating WPA, epoxy resin, and magnesium-based additives in asphalt mixtures to enhance their performance and durability. By utilizing plastic waste materials and optimizing their combination with epoxy reinforcement, along with the innovative use of magnesium-based additive, the findings contribute to the development of sustainable infrastructure materials and pave the way for further advancements in the field.

Reuse of plastic waste in asphalt mixtures with residual porous aggregates

The reuse of plastic and poor-quality residual aggregates in the manufacture of bituminous mixtures for paving could contribute to reclaim significant quantities in the pavement construction industry since certain polymers can enhance the mixture properties. This study investigates the potential use of waste from recycled polyethylene terephthalate (PET) in asphalt mixtures with extremely-vesiculated residual aggregates, which are also rejected in quarry production. In this research, the physical, compaction, and mechanical properties of asphalt mixtures with these marginal aggregates, different binder consistencies and PET contents replacing part of the aggregate are studied. The results indicate that limited proportions of waste PET (up to 1 %) are compatible with extremely porous aggregates and can improve certain mixture engineering properties, such as the resistance to water action and to rutting. These mixtures meet specifications for base courses and even for pavement surfaces under limited heavy-truck traffic, while contributing to the sustainability of asphalt pavements by reducing the extractive demand of natural resources and replacing them with waste materials.

The Potential Utilization of Plastic Waste as a Building Material

One of the innovations in utilizing plastic waste is to process it into Plastic Blocks for Wall Pairs (BPBPD). This research aimed to analyze the temperature required in melting used plastic and cooking oil for making BPBPD mixtures. Variations in the research are temperature under the range 180°C, 200°C, and 220°C. Comparison of the proportions of the mixture of plastic, oil, and coarse aggregate 5-10 mm, namely 1.5:1:0.5, 1:1:0.5, and 1:1:0.25. The types of plastic used are plastic bags, aluminum-coated plastic, and mica plastic. The parameters in this study are the compressive strength value, the initial rate of suction (IRS) value, the porosity value, and the water absorption rate. The study results showed that the minimum temperature for melting plastic bags and aluminum is 180°C, and for melting mica plastic is 220°C. The recommended proportion for making this BPBPD is a ratio of 1.5:1:0.5. The results of the IRS test on the plastic bags BPBPD ranged from 0.037-0.057 Kg/m2, the aluminum plastic BPBPD 0.030-0.057 Kg/m2, and the mica plastic BPBPD 0.033-0.043 Kg/m2. The water absorption rate for plastic BPBPD ranges from 0.233-0.378%, aluminum plastic BPBPD 1.644-4.233%, and mica plastic BPBPD 1.233-2.756%. Porosity results from the plastic bag BPBPD ranged from 0.355-0.931%, the aluminum plastic BPBPD 10.83-12.1%, and the mica plastic BPBPD 2.25-3.9%. In general, the compressive strength of BPBPD plastic bags, both without and with immersion, meets the minimum average compressive strength according to BSN 1989 with quality IV with the highest value in the 1.5:1:0.5 mixture of 38.2 Kg/cm2.

Economic viability analysis of recycling waste plastic as aggregates in green sustainable concrete

Plastic waste management is one of the major global challenges at present. Recycling single used plastic waste as partial replacement of natural aggregates in concrete may reduce problems regarding mismanagement of plastic waste and unsustainable utilisation of natural resources as aggregates. This concept has been explored in many studies and positive results are obtained, but it has not been materialized at a large scale due to the uncertainty regarding economic viability. The present study therefore focuses on the economic aspects of using Polyethylene based fine aggregates and Polyethylene Terephthalate based coarse aggregates as partial replacement (10%, 20%, 30% and 40%) of natural fine and coarse aggregates separately and simultaneously, with special emphasis given on environmental and social cost. A material flow diagram using STAN is first developed to calculate plastic waste generation. An industrial survey has been conducted to estimate production cost of plastic aggregates, while social cost as WTP is determined through CVM method. The result shows that the total cost of concrete decreases with increase of replacement percentage and cost reduction varies between 0.65% and 7.58% compare to conventional concrete depending on the percentage and type of replacement without compromising strength. So, alongside being hugely beneficial to environment and society in terms of reduction of leachate and greenhouse gas generation, micro-plastic pollution, requirement of landfill area, mosquito borne diseases, erosion, sedimentation, land loss etc.; the concept of recycling plastic waste as partial replacement of natural aggregates in concrete has been proved to be economically viable and beneficial too.

Application of soft computing in predicting the compressive strength of self-compacted concrete containing recyclable aggregate

AbstractSelf-compacting concrete (SCC) is a type of concrete known for its environmental benefits and improved workability. In this study, data-driven approaches were used to anticipate the compressive strength (CS) of self-compacting concrete (SCC) containing recycled plastic aggregates (RPA). A database of 400 experimental data sets was used to assess the capabilities of multi-objective genetic algorithm evolutionary polynomial regression (MOGA-EPR) and gene expression programming (GEP). The analysis results indicated that the proposed equations provided more accurate CS predictions than traditional approaches such as the linear regression model (LRM). The proposed equations achieved lower mean absolute error (MAE) and root mean square error (RMSE) values, a mean close to the optimum value (1.0), and a higher coefficient of determination (R2) than the LRM. As such, the proposed approaches can be utilized to obtain more reliable design calculations and better predictions of CS in SCC incorporating RPA.

RETRACTED: Fresh and mechanical performances of recycled plastic aggregate geopolymer concrete modified with Nano-silica: Experimental and computational investigation

Concerning environmental concerns, it has become crucial to invent and develop alternative construction materials that can replace ordinary Portland cement and use waste materials instead of natural aggregates in the production of concrete. An important advancement in this area is the utilization of recycled plastics to create geopolymer concrete, which helps reduce plastic waste and minimize the environmental impact of construction materials. Since plastics have become a significant environmental issue, it is imperative to find ways to recycle them for a sustainable future. Thus, this study was conducted involving the preparation of seventeen different mixtures of geopolymer concrete (GPC) in three stages. In the first stage, five GPC mixes were created with varying amounts of nano-silica (NS) ranging from 0 % to 4 %. The main objective of this stage was to determine the optimal NS content that could enhance the performance of the GPC matrix. In the second stage, recycled plastic aggregates (RPA) were introduced to replace a portion of the fine aggregates, ranging from 0.05 to 0.5 volume percentages. This aimed to assess the impact of RPAs on the fresh GPC and its mechanical properties. The third stage involved an analysis to improve the performance of the GPC compound incorporating RPAs. The optimal NS content identified in the first stage was utilized for all mixtures with RPA. Lastly, several modeling techniques, including artificial neural network, M5P tree, multiple linear regression, full quadratic, multi-expression programming, and linear regression, were employed to predict the compressive strength of the GPC compound. The results demonstrated that the addition of nano-silica increased the compressive strength of the GPC mixtures by 6.3 %, 13.4 %, 20.5 %, 21 %, and 21.9 % at curing ages of 3, 7, 28, 90, and 180 days, respectively, when using 3 % NS content compared to the control GPC mixture. However, the inclusion of NS had a negative impact on the workability of the GPC mixes. Furthermore, incorporating RPAs reduced both the workability and compressive strength of the GPC compound. In the end, the results obtained from the modeling analysis revealed that the compressive strength of GPC could be predicted with a high degree of accuracy by taking into account the mixture proportions of its constituents. Among the various techniques used, it was found that the artificial neural network model outperformed other methods in accurately forecasting the compressive strength of GPC. This indicates that the neural network model is a superior and reliable approach for estimating the strength characteristics of GPC, providing valuable insights for optimizing its composition and enhancing its overall performance.

UTILIZATION OF MODIFIED PLASTIC WASTE ON THE POROUS CONCRETE BLOCK CONTAINING FINE AGGREGATE

Modification of plastic waste to be use as a replacement of coarse aggregate on the manufacturing of porous concrete block is presented in this paper. Different proportions of sand content were used with percentage of 1%, 5% and 10% by total weight of the sample to investigate its effects on the performance of porous concrete blocks based on some conducted tests i.e., compression and flexural load resistance, porosity, and infiltration rate tests. The results show that the porous concrete block with 5% of sand addition showed better strength properties compared to other mixtures. With 5% modified PET coarse aggregate, the compressive strength decreased for about 26%. Similar trends can be also observed when using PP and HDPE plastic aggregate. However, the inclusion of PET aggregate in porous concrete blocks with 5% of sand inclusion does not significantly show better strength indicating the weak bonding between plastic and cement mortar was performed in porous concrete block matrix as evident through the Scanning Electron Microscopy analysis. The formation of pores and higher permeability can be also expected after adding PET plastic waste as seen in porosity and infiltration rate results. Furthermore, the utilization of coarse aggregate made from plastic waste in porous concrete blocks containing fine aggregate is a potential solution on plastic waste management for permeable pavement including foot traffic and light load application.

Valorization of plastic waste in concrete for sustainable development

Environmental preservation issues are hot topics, as they have come to the fore in recent years due to climate change and the significant pollution that is occurring in the environment especially that related to plastic waste, because the problem of their disposal has become a problem from which governments suffer. We have therefore decided in this study to recycle and recover plastic and are going to study the possibility of replacing the aggregates present in the concrete with plastic granules and to study the physical and mechanical properties of this type of concrete, where the aggregates (sand + gravel) in the concrete will be replaced by plastic aggregates (PET) in variable proportions (0%, 5%, 10%, 15%, 20%, 25%, 30%) in relation to its volume. The results obtained have shown good results, especially in terms of reducing the weight of the concrete and in terms of sound insulation, The aggregates (PET) reduce the compressive strength but not significantly, in the end we can say This type of concrete opens up new horizons and gives a new vision of concrete that respects the environment and sustainable development.