International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 13 Issue: 05 | May 2026 www.irjet.net p-ISSN: 2395-0072
Lightweight Aggregate Concrete (LWAC) Incorporating Plastic Waste as Partial Aggregate Replacement
Prof. R R Chandanshive1, Prof. T K Shikalgar2, Prof. V M Sanade3
123Assistant Professor, Department of Civil Engineering, TKIET Warana nagar
Abstract-The continuous increase in plastic waste generationanddepletionofnaturalaggregateresourceshave become major environmental and sustainability concerns worldwide. Disposal of plastic waste in landfills and open environmentsleadstosoilpollution,watercontamination,and ecologicalimbalancebecauseplasticsarenon-biodegradable in nature. At the same time, the construction industry consumes enormous quantities of natural aggregates for concrete production, resulting in excessive exploitation of natural resources. In this context, the utilization of plastic waste in Lightweight Aggregate Concrete (LWAC) has emerged as a promising sustainable solution. This study reviews the potential application of waste plastic materials such as Polyethylene Terephthalate (PET), High-Density Polyethylene (HDPE), Polypropylene (PP), and Expanded Polystyrene (EPS) as partial replacement for conventional aggregatesinconcrete.Theinfluenceofplasticaggregateson workability, density, compressive strength, tensile strength, flexuralstrength,thermalinsulation,anddurabilityproperties of LWAC is discussed in detail. Previous studies indicate that optimumreplacementlevelscansignificantlyreduceconcrete densitywhilemaintainingacceptablestructuralperformance for non-structural and selected structural applications The incorporation of plastic waste in concrete also contributes toward sustainable waste management, reduction in landfill burden, and conservation of natural aggregates. However, excessive replacement percentages may negatively affect mechanical properties because of weak interfacial bonding between plastic particles and cement paste. Therefore, optimization of replacement levels and enhancement of bonding characteristics are important for achieving durable andstructurallyefficientlightweightconcrete. Thestudyalso highlights major research gaps, challenges, and future research opportunities related to plastic-based LWAC. The findings may support development of environmentally sustainable construction materials and contribute toward circular economy practices in the construction industry.
Key Words: Lightweight Aggregate Concrete, Plastic Waste, Sustainable Concrete, PET, HDPE, Aggregate Replacement, Durability.
1. INTRODUCTION
Plastic waste accumulation has become one of the most serious environmental challenges due to rapid industrialization, urbanization, and increasing consumer demandforplasticproducts.Plasticsareextensivelyusedin packaging, household materials, electronic devices,
automotiveindustries,andconstructionapplicationsbecause of their lightweight nature, durability, flexibility, and low manufacturingcost.However, improperdisposal of plastic waste has resulted in severe environmental pollution, including blockage of drainage systems, contamination of waterbodies,andgenerationofmicroplastics.
According to recent environmental studies, millions of tons of plastic waste are generated every year worldwide, whileonlyasmallportioniseffectivelyrecycled.Mostplastic waste is either dumped in landfills or burned in open environments,leadingtoharmfulgreenhousegasemissions and long-term ecological damage. Therefore, sustainable methods for plastic waste utilization and recycling have becomeanurgentnecessity.
Concrete remains one of the most widely used construction materials because of its high compressive strength, durability, versatility, and economic feasibility. Aggregates constitute approximately 60–75% of the total volume of concrete and significantlyinfluence its physical, mechanical, and durability properties [10]. The growing demandforconcreteproductionhasincreasedconsumption of natural aggregates, leading to depletion of natural resources and environmental degradation caused by quarryingactivities.
LightweightAggregateConcrete(LWAC)isaspecialized type of concrete produced using lightweight aggregates havinglowerdensitycomparedtoconventionalaggregates. The density ofLWAC generally ranges below 2000 kg/m³. Lightweight concrete offers several advantages such as reduction in dead load of structures, improved thermal insulation,betterfireresistance,easierhandling,andlower transportationcosts.
Conventional lightweight aggregates include expanded clay, pumice, shale, vermiculite, perlite, and fly ash aggregates. In recent years, researchers have focused on utilizingindustrialby-productsandrecycledwastematerials as lightweight aggregate alternatives to improve sustainabilityandreduceenvironmentalimpact.
WasteplasticmaterialssuchasPET,HDPE,PP,andEPS haveshownsignificantpotentialforuseaspartialaggregate replacement materials in concrete [7], [8], [9]. The lightweightnatureofplasticaggregatescontributestoward reductioninconcretedensityandimprovementinthermal insulationcharacteristics.Furthermore,utilizationofwaste plastic in concrete provides an environmentally friendly solutionforrecyclingnon-biodegradablewastematerials.
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 13 Issue: 05 | May 2026 www.irjet.net p-ISSN: 2395-0072
Several researchers have reported that moderate replacement levels of plastic aggregates can produce lightweightconcretewithacceptablecompressivestrength and durability properties suitable for non-structural and selected structural applications. In addition, plastic aggregates may improve impact resistance and energy absorptioncapacitybecauseoftheirflexiblenature.
Despitetheseadvantages,incorporationofplasticwaste in concrete also presents certain challenges. Excessive replacementlevelsmayreducecompressivestrength,tensile strength,andbondcharacteristicsbecauseplasticsurfaces are generally smooth and hydrophobic. Weak interfacial bonding between plastic particles and cement paste may increase porosity and reduce durability performance [11]. Therefore, optimization of replacement percentage and surfacetreatmenttechniquesarenecessaryforimprovingthe engineeringperformanceofplastic-basedLWAC.
Thepresentstudyfocusesonreviewingtheproperties, advantages, limitations, and future possibilities of LightweightAggregateConcretecontainingplasticwasteas partial aggregate replacement. The study also identifies importantresearchgapsandprovidesrecommendationsfor futureresearchinsustainableconcretetechnology.
1.1 SIGNIFICANCE OF THE STUDY
The utilization of waste plastic in Lightweight Aggregate Concrete is important from environmental, economic, and technicalperspectives.Incorporationofrecycledplasticinto concretehelpsreducelandfilldisposalandconservesnatural aggregateresources.
From a sustainability viewpoint, plastic-based LWAC can reducetheenvironmentalimpactassociatedwithaggregate quarryingandconcreteproduction.Thelightweightnatureof plastic aggregates decreases concrete density, thereby reducingdeadloadandtransportationcosts.
Technically,thestudycontributestowardunderstandingthe influenceofplasticaggregatesonworkability,compressive strength, tensile strength, durability, thermal conductivity, and density of concrete. The findings may support development of eco-friendly and lightweight construction materialssuitableformoderninfrastructure.
2. LITERATURE REVIEW
Several researchers have investigated the use of waste plasticinlightweightconcreteproduction.Hamadaetal.[9] reviewed the application of plastic waste as aggregate material andreported that plasticaggregatessignificantly reduceconcretedensityandimprovesustainability.
DelReyCastilloetal.[8]developedartificiallightweight aggregates manufactured from recycled plastic waste and
observed improvements in thermal insulation properties andreductioninunitweightofconcrete.
Bashaetal.[7]investigatedthemechanicalandthermal behaviorofrecycledplasticaggregateconcreteandreported that moderate replacement levels maintained acceptable compressive strength while improving lightweight characteristics.
Studies involving PET waste aggregates demonstrated reductions in compressive and tensile strength at higher replacementlevelsbecauseofweakinterfacialbondingand increased porosity [15]. Parsons and Nwaubani [11] also reportedreductionindurabilityperformancewithincreased plasticaggregatecontent.
Recent research by Amjad et al. [6] indicated that incorporation of nano-iron oxide and sisal fibers can improvemechanicalanddurabilityperformanceofplastic aggregateconcrete.
Overall,previousstudiesconfirmthatwasteplasticcanbe effectively utilized in LWAC; however, optimization of replacement percentage and durability enhancement remainsnecessary.
Table1.ComparisonofPreviousStudiesonPlasticBasedLWAC
Researcher Type of Plastic Used Replaceme ntLevel Major Findings Limitati on
Hamada et al.[9]
Mixed Plastic Waste 5–30%
Bashaetal.[7] Recycled Plastic Aggregate 10–20%
DelReyCastillo etal.[8] Artificial Plastic Aggregate 10–25%
Dawood et al.[15] PET Waste 5–20%
Parsons et al.[11] ABS Plastic Aggregate 10–30%
Amjadetal.[6] Plastic Aggregate +Fibers 30%
Reduced density and improved sustainability
Improved thermal insulation
Lower unit weight and better insulation
Lightweight concrete production
Sustainable aggregate alternative
Improved durabilityand strength
Reduced strength athigher replacem ent
Weak bonding characte ristics
Reduced compres sive strength
Increase d porosity
Durabilit y reductio n
Complex mix design
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 13 Issue: 05 | May 2026 www.irjet.net p-ISSN: 2395-0072
3. RESEARCH GAP
Although considerable research has been carried out on plasticaggregateconcrete,severalimportantresearchgaps stillexist:
1.Limitedinformationisavailableregardinglong-term durabilityperformanceofplastic-basedLWAC.
2.Standardguidelinesforplasticaggregategradationand surfacetreatmentarenotyetestablished.
3.Moststudiesfocusonlyoncompressivestrength,while limitedworkhasbeenconductedonthermalconductivity, shrinkage,andfireresistance.
4. The optimum percentage of plastic replacement for structural-gradeLWACisstilluncertain.
5.Limitedstudiesareavailableonlife-cycleassessment andlarge-scalefieldapplications.
6. The effect ofcombined curing environments suchas saline and alkaline conditions requires further investigation.
4. OBJECTIVES
1. To develop Lightweight Aggregate Concrete using plasticwasteaspartialaggregatereplacement.
2. To determine the optimum percentage of plastic aggregatereplacement.
3.Toevaluatecompressive,tensile,andflexuralstrength ofplastic-basedLWAC.
4. To study durability characteristics including water absorptionandchloridepenetrationresistance.
5. To evaluate density reduction and thermal performance.
6.Toassesssustainabilityandenvironmentalbenefitsof plasticaggregateutilization.
Clean potable water was used for mixing and curing of concretespecimens.
6. METHODOLOGY
Theproposedmethodologyconsistsofthefollowingstages:
1. Literature review and identification of research gaps.
2. Selectionandcharacterizationofmaterials.
3. Preparationofplasticaggregates.
4. Mix design of LWAC with different replacement levels.
5. Castingandcuringofconcretespecimens.
6. Mechanicaltestingofhardenedconcrete.
7. Durabilityevaluation.
8. Statisticalanalysisandinterpretationofresults.
7. TESTS CONDUCTED
FreshConcreteTests
SlumpConeTest
DensityTest
MechanicalTests
CompressiveStrengthTest
SplitTensileStrengthTest
FlexuralStrengthTest
ModulusofElasticityTest
Pull-OutBondStrengthTest
UltrasonicPulseVelocityTest
DurabilityTests
WaterAbsorptionTest
SorptivityTest
RapidChloridePenetrationTest(RCPT)
AcidResistanceTest
AlkaliResistanceTest
ThermalTest
5.
MATERIALS USED
1.OrdinaryPortlandCement(OPC)
Ordinary Portland Cement was used as the primary bindingmaterialforconcreteproduction.
2.FineAggregate
Natural river sand conforming to standard grading requirementswasusedasfineaggregate.
3.LightweightAggregate
Lightweightaggregatessuchasexpandedclayandpumice wereusedtoreduceconcretedensity.
4.PlasticWasteAggregates
Plastic wastes including PET, HDPE, and PP were collected,cleaned,shredded,crushed,andgradedbefore useinconcrete.
5.Admixtures
Superplasticizerswereusedtoimproveworkabilityand consistencyofconcretemixes.
6.Water
ThermalConductivityTest
Table 2. AdvantagesandLimitationsofPlastic-Based LWAC
Advantages Limitations
Reduces plastic waste disposal Reduced compressive strength at higher replacement
Conservesnaturalaggregates Weak bonding with cement paste
Reducesconcretedensity Increasedporosity
Improvesthermalinsulation Durabilityconcerns
Supports sustainable construction Lack of standard specifications
Reduces dead load of structures Limitedfieldapplications
International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056
Volume: 13 Issue: 05 | May 2026 www.irjet.net p-ISSN: 2395-0072
8. FUTURE SCOPE
The future scope of plastic-based Lightweight Aggregate Concreteisextensiveduetogrowingenvironmentalconcerns and increasing emphasis on sustainable infrastructure development.Althoughseveralstudieshavedemonstrated the feasibility of utilizing waste plastic in concrete, many aspectsstillrequiredetailedinvestigation.
Future research may focus on improving the interfacial bonding between plastic aggregates and cement paste throughchemicaltreatment,surfaceroughening,andcoating techniques. Such modifications may help improve compressivestrengthanddurabilityperformance. Further studies are also required on long-term durability propertiessuchascreep,shrinkage,carbonationresistance, freeze-thawresistance,sulfateattackresistance,andchloride penetration behavior under aggressive environmental conditions.
Theincorporationofsupplementarycementitiousmaterials, nanomaterials,fibers,andhybridreinforcementsystemsmay furtherenhancethemechanicalanddurabilityperformance of plastic-based LWAC. Advanced materials such as nanosilica,grapheneoxide,andfiber-reinforcedpolymerscanbe exploredforimprovingmicrostructuralcharacteristics.
Another important future research area involves thermal insulation,acousticperformance,andfireresistancebehavior of plastic aggregate concrete. Since plastic materials are sensitivetotemperature,detailedfireperformanceanalysis isnecessarybeforelarge-scalestructuralapplications.
Life-cycleassessmentandcost-benefitanalysisshouldalsobe performed to evaluate the environmental and economic feasibilityofplastic-basedlightweightconcrete.Inaddition, large-scale field implementation and real-time structural monitoring can provide valuable practical data regarding performanceunderactualserviceconditions.
Artificialintelligenceandmachinelearningtechniquesmay also be applied for optimization of concrete mix design, predictionofstrengthproperties,anddurabilitymodelingof plastic-basedLWAC.
9. CONCLUSIONS
The utilization of waste plastic as partial aggregate replacement in Lightweight Aggregate Concrete offers a sustainablesolutionforaddressingenvironmentalpollution anddepletionofnaturalresources.Plastic-basedLWACcan significantly reduce concrete density while improving thermalinsulationcharacteristics.Previousstudiesindicate that moderate replacement levels provide acceptable mechanical and durability performance. However, higher replacement percentages may reduce strength because of weakinterfacialbondingandincreasedporosity.
Furtherresearchisrequiredtooptimizemixproportions, improve bonding mechanisms, and evaluate long-term durability performance. The successful implementation of plastic-based LWAC may contribute significantly toward sustainable infrastructure development and circular economypractices.
10. REFERENCES
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