Effects of aggregate size and glass powder fineness on the performance and durability of self-compacting concrete with recycled laminated glass.

Abstract

The sustainability of recycled glass in concrete closely depends on the ability to mitigate the alkali-silica reaction (ASR), a significant challenge stemming from the chemical incompatibility between glass and cement. Accordingly, this study aims to quantify the coupled effects of recycled laminated glass particle size and glass-powder (GP) fineness, under ASR-promoting conditions, on the dimensional stability of self-compacting concrete (SCC). It relates these effects to mechanical performance and transport properties and elucidates the underlying mechanisms through microstructural analyses. Three aggregate sizes (3/8, 8/12.5, and 8/16 mm) and two GP Blaine values (3570 and 5797 cm²/g) were incorporated into SCC mixes and cured for 365 days in baths at 38 °C, with or without NaOH added to the mixing water. Additionally, mortar specimens were treated in an autoclave at 127 ± 2 °C to evaluate dimensional variations. The results highlight the importance of particle sizes and glass powder fineness. Microstructural analyses (XRD, TGA/DTA, and SEM/EDX) revealed significant pozzolanic activity of the finer glass powder, reducing calcium hydroxide content and promoting C-S-H gel formation with lower Ca/Si ratios. High-fineness glass powder also showed notable benefits in improving compressive strength and reducing permeability, enhancing the concrete's ability to limit chloride ion diffusion. Conversely, larger glass aggregates (8/16 mm) caused more significant expansion than smaller aggregates (8/12.5 mm).