Structural assessment and conditional monitoring of light rail transit (LRT) line

Abstract

This research presents the findings of structural assessment and conditional monitoring of Light Rail Transit (LRT) Line. The assessment was aimed to measure the present condition in order to update the structure inventory including further detailed inspection and remedial works. The LRT elements investigated are stations, viaducts, piers, guideways and tunnels. The detailed investigation consist of test carried out includes petrographic, carbonation; electrode potential measurement, half cell testing, and concrete cover depth. The methodology of this study carried out through a study of project documents, a routine of preliminary structure assessment, detailed inspection, an analysis of the results of testing conducted upon the sample material from the affected structure and remedial works. The preliminary assessment shows that 10 Piers, an internal viaduct, 3 tunnels stretch, 6 stations and an abutment require further detailed inspection. The findings indicate that the majority of the defects monitored and tested at the viaduct structures, station and tunnels can be dealt with as part of routine maintenance with the exception of the defects noted at the Abutment P21/40. All these elements have been subjected to design review and suitable remedial works are recommended to be undertaken immediately to maintain the integrity of the structures. The study concluded the main causes of the extensive cracking and efflorescence on the abutment pilecap due to construction issues and detailing of abutment extension due to replacement piles, poor curing practices lead to early age plastic and thermal cracking, heat of hydration peak temperature rise during the concrete pour resulting in Delayed Etringite Formation (DEF) and cover provision beyond code recommendations. From this research, appropriate remedial works identified and carried out at the selected locations.