Research on Early Age Deformation of High Performance Concrete by Fiber Bragg Grating Sensor

Abstract

For high performance concrete (HPC), due to its low water cement ratio and addition of mineral admixtures, pretty high autogenous shrinkage and thermal deformation occur at early age of HPC casting (especially before hardening), which may lead to early age cracking of HPC structures, and influence the durability of HPC. This paper has monitored the early age properties of HPC successfully by embedded FBG strain sensor. The results show that the deformation increases rapidly within the first day after HPC casting. And its value is up to 57 mu epsilon, which is the 35% of two-week deformation (165 mu epsilon). Considering the durability and permeability of HPC, first-day deformation is pretty high and can not be neglected. Also, FBG monitoring system has been used to measure early age deformation and temperature of HPC retaining wall simultaneously. Temperature compensation for FBG strain sensor is always necessary for accurate strain monitoring. The monitoring technique used here can be extended to concrete early age behavior monitoring in mass concrete structure with any size.