V3I9P19

Durability Performance of E-Waste Plastic Incorporated Ambient-Cured Metakaolin–Fly Ash Geopolymer Concrete

Dr. Rajiv Khatri¹, Rakesh Kumar Rathore², Guru Sharan Mishra^3*, Dr. Chandra Prakash Gour⁴

Abstract

The disposal of electronic waste (e-waste) and the environmental burden associated with Portland-cement production are two complementary sustainability challenges for the construction sector. This study experimentally investigates the durability of e-waste plastic (EWP) incorporated ambient-cured metakaolin–fly ash geopolymer concrete (MK–FA GPC). An optimized binary geopolymer matrix containing 60% metakaolin and 40% fly ash was developed using 10 M NaOH, a liquid-to-binder ratio of 0.60 and a sodium-silicate-to-sodium-hydroxide ratio of 2.5. EWP, characterized in the thesis as a low-density, predominantly flaky/elongated material with a maximum size of 10 mm, specific gravity of 1.10 and water absorption of 0.10%, was used as partial coarse-aggregate replacement at 0, 2.5, 5, 7.5, 10, 12.5 and 15%. Durability was assessed using water absorption, sorptivity, rapid chloride permeability, 5% sulphuric-acid exposure, sodium-sulphate exposure and saltwater exposure. Mechanical properties and non-destructive measurements were used to establish the engineering trade-off associated with increasing EWP. Water absorption decreased from 4.97% for the control to 4.38% at 5% EWP and 3.45% at 15% EWP; 120-min sorptivity decreased from 0.060 to 0.047 and 0.031, respectively. Ninety-day RCPT charge decreased from 881 C for the control to 863 C at 5% and 803 C at 15% EWP. At 120 days, 5% EWP reduced sulphuric-acid mass loss from 25.35 to 21.54% and strength loss from 28.92 to 22.88%; sodium-sulphate strength loss decreased from 9.56 to 8.23%; and saltwater mass and strength losses decreased from 2.31 to 1.80% and 8.16 to 7.15%, respectively. In contrast, 28-day compressive strength decreased from 42.31 MPa for the control to 39.34 MPa at 5% and 26.86 MPa at 15% EWP. The results demonstrate that EWP can improve selected transport and chemical-exposure indicators while progressively reducing mechanical strength. Within the investigated range, 5% EWP provided the most balanced performance and retained an M30-level compressive strength. The findings support the feasibility of EWP utilization in ambient-cured MK–FA GPC but also demonstrate that lower absorption or chloride charge alone cannot establish comprehensive durability. Polymer-specific characterization, leaching, thermal/fire performance, long-term diffusion, coupled exposures and life-cycle assessment are required before field-scale implementation.

Keywords:

E-waste plastic; geopolymer concrete; metakaolin; fly ash; durability; sorptivity; chloride permeability; sulphuric acid; sulphate attack; saltwater; ambient curing; recycled aggregate.