Optical Fibre Sensor System for Real-Time Concrete Compressive Strength Monitoring

The development of mechanical strength in concrete during curing is a crucial factor in evaluating the structural integrity and quality control of concrete. This study proposes the application of an optical fibre-based Mach-Zehnder Interferometric (MZI) system for non-destructive monitoring of the compressive strength development of unreinforced concrete beams. Low- and high-strength concrete mixtures were cast, with a single-mode fibre (SMF) embedded at the centre of the beam. In each beam, a single-mode fibre (SMF) was embedded at the centre of the beam. The samples were cured in a temperature-controlled water tank, and compressive strength was continuously monitored in each mixture for 28 days. The logarithmic slopes derived from the MZI-calibrated compressive strength development obtained a sensitivity of 5.373 MPa/ln(days) for the low-strength mix and 19.635 MPa/ln(days) for the high-strength mix, in comparison to the corresponding cube-derived strength sensitivity of 4.782 and 18.178 MPa/ln(days), respectively. This increased sensitivity verifies the embedded sensing arm of the MZI reliability as a non-destructive tool for measuring in-situ strength growth across mixture quality.