Use of “Plazrok” Aggregate to Produce Durable Grade 3.0 and 4.0 Concrete
The rising demands for high-quality aggregates, alongside efforts to reduce the environmental impact of mining, have encouraged using recycled material as aggregate in concrete. Over the decades, plastic production has surged, yet only 25% of used plastics have been recycled or incinerated (US EPA 2023). Numerous studies investigating the strength development and modulus of elasticity of concrete containing plastic waste as an aggregate have reported reduced strength and stiffness with increasing replacement levels. Despite this reduction in strength compared to traditional mixes, Kansas State University developed mixtures containing Plazrok, a commercially available extruded product containing fly ash, waste plastics, and glass, that achieved sufficient strength (5264 psi) to be classified as grade 4.0 concrete. The increasing replacement of mined aggregate with Plazrok was found to have a greater impact on the compressive strength than the modulus of rupture and tensile strength. Furthermore, structural testing of a 10-inch by 6-inch by 12-foot beam demonstrated that a beam containing Plazrok (at 30% replacement level) performed similarly to other lightly reinforced normal-weight concrete members. Moisture corrections (to account for the wash water of the concrete truck drum) were not applied during this preliminary investigation, therefore, the reported mechanical properties may be an underestimation. Another issue identified during this preliminary study was the potential for Plazrok to float to the top of the forms, but no segregation was observed in hardened concrete samples. Building on these experiences, the primary goal of this study is to develop grade 3.0 and 4.0 concrete with maximum possible Plazrok content. Environmental Produce Declarations (EPDs) for successful mixture designs will be produced to help demonstrate the environmental impact of such concretes. Segregation will be monitored as it is a known possible issue and, if observed, will be controlled by modifying the viscosity of the paste and/or increasing the fine/coarse aggregate ratio for the concrete mixture. Another focus area will be studying the freeze-thaw durability of Plazrok concrete. Since Plazrok particles have low absorption and stiffness, and the concrete containing Plazrok retained tensile strength (compared to the control), it could be hypothesized to have satisfactory freeze-thaw durability provided the paste is protected with adequate air content. If deemed freeze-thaw durable, concrete containing Plazrok could be suitable for outdoor applications like sidewalks, provided they meet the strength requirement for grade 4.0 concrete. Since aggregates impact the stress-strain behavior of concrete, this project will also document elastic properties for plazrok concrete. Furthermore, impact on other mechanical, durability, and fresh properties such as modulus of rupture, shrinkage, permeability, slump, etc. will also be recorded.
Language
- English
Project
- Status: Active
- Funding: $82,927.00
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Contract Numbers:
K-TRAN: KSU-26-6
RE-0924-01
C2256
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Sponsor Organizations:
Kansas Department of Transportation
Eisenhower State Office Building
700 SW Harrison Street
Topeka, KS United States 66603-3754 - Performing Organizations: Manhattan, KS United States 66506
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Principal Investigators:
Panchmatia, Parth
- Start Date: 20250815
- Expected Completion Date: 20270215
- Actual Completion Date: 0
Subject/Index Terms
- TRT Terms: Artificial aggregates; Concrete; Environmental impacts; Mix design; Plastics; Recycled materials
- Subject Areas: Construction; Design; Environment; Highways; Materials; Pavements;
Filing Info
- Accession Number: 01976246
- Record Type: Research project
- Source Agency: Kansas Department of Transportation
- Contract Numbers: K-TRAN: KSU-26-6, RE-0924-01, C2256
- Files: RIP, STATEDOT
- Created Date: Jan 13 2026 4:28PM