Preliminary study on influence of UV radiation on the light transmittance of light-transmitting concrete

This study presented a preliminary investigation into the effect of ultraviolet (UV) radiation on the light transmittance properties of light-transmitting concrete (LTC) embedded with polymethyl methacrylate (PMMA) optical fibres. Light transmittance tests, FTIR, UV–VIS spectroscopy, and SEM analyses were conducted on LTC and PMMA optical fibres to assess the impact of UV radiation on the light transmittance of LTC. Following 1 h of accelerated UV exposure, surface smoothing, oxidation and densification was induced rather than crosslinking or chain scission in the PMMA fibres, resulting in enhanced light transmittance of the LTC. The extent of surface modification and the corresponding improvement in optical performance were found to be fibre diameter-dependent. Fibres with a 1.0 mm diameter exhibited the most uniform microstructural rearrangement and the highest improvement in light transmittance after UV exposure, whereas larger fibres (2.0 mm) and smaller fibres (0.75 mm) showed suboptimal changes attributed to non-uniform oxidation and limited exposed surface area, respectively. The short-term UV exposure did not affect the compressive strength of LTC. These findings provide insight into the mechanisms driving optical performance enhancement of LTC under short-term UV exposure and offer practical guidance for fibre diameter selection in LTC applications, considering trade-offs between optical performance, durability and cost. Further investigations involving prolonged UV exposure and environmental weathering effects are recommended to assess the long-term durability of LTC in real-world conditions.