Compressive Strength of Light-Transmitting Concrete (LTC) Incorporated with Optical Fibre

This paper aims to investigate the effect of incorporating optical fibre on the concrete compressive strength by varying the fibre diameter and fibre grid (spacing) in light-transmitting concrete (LTC). Optical fibres made of polymethymethacrylate (PMMA) are used as translucent material for the production of LTC. The fibre diameters considered are 0.75 mm, 1.0 mm, 1.5 mm, and 2.0 mm, while the fibre grids are 4 × 4 grids (25 mm), 5 × 5 grids (18.75 mm) and 6 × 6 grids (15 mm). Self-compacting concrete (SCC) was used for casting. The specimens were tested for UPV test and compressive strength test on the 7th and 28th day. SEM analysis was also carried out to observe the fibre-matrix interface of the LTC specimens. The addition of optical fibre did not necessarily deteriorate the strength of the concrete. It was found that LTC with a fibre diameter of 1.0 mm had the highest compressive strength, while thereafter the strength started to decrease with increasing fibre diameter. It was found that the smaller fibre spacing reduced the concrete compressive strength. All specimens reached the design strength of 40 MPa. The UPV results showed that all specimens were of good quality regardless of the incorporation of the optical fibre. The microstructure analysis showed that there were no visible gaps within the fibre-matrix interface of all LTC specimens except for LTC with a fibre diameter of 1.5 mm. Overall, the effect of the use of optical fibre on the concrete compressive strength is insignificant.