Capturing Internal Swelling Reactions (ISR) Damage in Concrete Through the Damage Rating Index (DRI)

Concrete, building most of our infrastructure, is relied upon to provide safe and long-lasting uninterrupted flow of goods and services to the public. However, as deterioration in concrete may be a result of service lives coming to an end, in some cases, factors that were unknown at the time of construction accelerate the process. Such distress mechanisms include alkali-silica reaction (ASR), freezing and thawing (FT), and sulphate attack among which delayed ettringite formation (DEF) make up the three major internal swelling reactions (ISR) known to date. With the rise of more efficient concrete materials comes the lack of field performance for which there is a need to identify damage on its early onset. The damage rating index (DRI) is a microscopy tool currently used in North America to semi-quantify damage in concrete. The DRI combined with other tools such as mechanical/durability property loss, the stiffness damage test (SDT), and characterization of the reaction products can provide a full profile of the damage. This work therefore offers an overview of the DRI procedure and its adaptability to other distress mechanisms such as DEF at a representative scale while highlighting its accessibility worldwide due to its low cost and energy compared to other tools.