Durability Performance Criteria for Precast RC Box Units and Repair Measures Based on Nondestructive Testing and Evaluation

Abstract

This paper presents the durability performance criteria for precast reinforced concrete (RC) box units for long-term durability against corrosion deterioration. This paper also presents the condition evaluation of precast RC box units constructed (at site) for road under bridge (RUB) that were exposed to open atmosphere for a period of about seven to eight years. This warranted the evaluation of the quality, integrity, strength, and durability of precast RC box units. Nondestructive testing and evaluation (NDT&E) reveal that some portions of RC box units are found to be of poor quality showing voids, honeycombing, and very low cover thickness to the rebar. The study shows that satisfying the minimum compressive strength criteria will not be sufficient for ensuring quality, integrity, and long-term durability of an RC structure since the deficiency in terms of poor quality and insufficient rebar cover thickness initiated corrosion deterioration at some portions in the selected RC box units. The detailed comprehensive investigation emphasizes the urgent need for the implementation of ‘durability performance’ criteria, in addition to the strength criteria for ensuring the long-term durability of the as-built structure. Necessary repair measures are suggested to enhance the long-term durability of RUB.