Thermal transmission characteristics of plastic optical fibre embedded light transmitting concrete

Innovations among the Civil Engineering fraternity have focused mainly on alternate materials and environmentally friendly materials in the recent past. Light transmitting concrete has been developed to reduce the energy demand of illumination. Achieving transmission is done by embedding glass or plastic optic fibres in concrete. The applicability of plastic optic fibres and their transmission behaviour with temperature change is critical to understanding the implementation of the material in various temperature regions, mainly due to its low melting point. The insulation properties will dictate the safety and comfort of the inhabitants. If any, the thermal deterioration of fibres can affect the transmittance and seriously limit the efficiency and applicability of the material. The study aims to quantify the thermal transmittance to understand the safe application, efficiency and behaviour under prolonged exposure to elevated temperature. To achieve this, light transmitting concrete cubes were subject to a light box test with an infrared light source, and the optical and thermal transmittance were measured. Samples contained between 1 and 7 optical fibres of either 0.5 mm or 1 mm diameter spaced at 12 mm or 15 mm. The material was exposed to elevated temperatures for up to 4 h as the temperatures stabilised beyond this. Regression analysis of the obtained data was also undertaken to validate the obtained results and the inferences. The findings broadly indicate a direct relationship between time, number of fibres and temperature. The distance of placement of the sample from the source, on the other hand, shows an inverse relationship to thermal transmission.