Environmental safety of electronic and construction and demolition waste based geopolymer breakwaters under simulated marine leaching

Wijesekara, KKDA, Carnacina, I ORCID: 0000-0001-5567-7180, Sadique, M ORCID: 0000-0001-7967-2659, Dave, U and Abdullah, MMAB (2026) Environmental safety of electronic and construction and demolition waste based geopolymer breakwaters under simulated marine leaching. Scientific Reports. ISSN 2045-2322

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Abstract

This study presents the evaluation of the environmental performance of a geopolymer based breakwater using a novel dual-waste valorisation approach that combines electronic waste (e-waste) derived sodium silicate from cathode ray tube glass (CRT) as a geopolymer activator, and construction and demolition waste (C&DW) aggregates. It will systematically investigate the leaching of major (Ca, Si, Al, Mg, Na) and trace/heavy metals (Cr, As, Zn, Fe, Pb, Ni, Cd, Cu) under simulated marine exposure. Geopolymer blocks incorporating e-waste derived sodium silicate and C&DW aggregates were compared with ordinary Portland cement (OPC) concrete and commercial silicate-based geopolymers. Standard dynamic surface leaching tests were performed in deionized water (DIW) and seawater (SW) for 64 days, with extrapolated predictions for a 50-year service life. Cumulative release of major ions during 64-day immersion ranged from 3.5 to 700 gm−2, while trace/heavy metals remained within 30–150 mgm−2. Extrapolation over 50 years indicated that all trace/heavy metals, including Pb, Cd, Ni, Cu, Mn, As, Cr, Zn, and Fe, would remain below 1 gm−2, while abundant elements such as Al, Mg, Si, Na, and Ca would remain below 1 kgm−2 in seawater. Higher Na (in GEO-RSiA-NA) and Ca (in NC-NA and GEO-RSiA-RA) releases were observed in DIW compared to SW, confirming its more aggressive leaching environment. Overall, trace/heavy metal concentrations remained well below Dutch regulatory thresholds, confirming the environmental safety of geopolymer breakwaters. These findings demonstrate the feasibility of recycled silicate–aggregate geopolymers as a sustainable breakwater material with reduced carbon footprint and controlled environmental impact. Further field validation under real hydrodynamic forces is recommended.

Item Type:	Article
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TC Hydraulic engineering. Ocean engineering
Divisions:	Civil Engineering and Built Environment
Publisher:	Nature Publishing Group
Date of acceptance:	11 June 2026
Date of first compliant Open Access:	26 June 2026
Date Deposited:	26 Jun 2026 13:41
Last Modified:	26 Jun 2026 13:41
DOI or ID number:	10.1038/s41598-026-58190-x
URI:	https://researchonline.ljmu.ac.uk/id/eprint/28900

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