Abstract
Alkali-silica reaction (ASR) is a deleterious chemical reaction affecting the durability and service life of concrete structures worldwide. Specifications and recommendations were produced in many countries to ensure that non-reactive aggregates are used in concrete construction or, when reactive aggregates must be used, appropriate preventive measures are implemented. Such recommendations, especially those related to the use of supplementary cementitious materials (SCM) to prevent ASR, are generally based on laboratory investigations, but preferably on field performance surveys of concrete structures where such measures have been implemented. Over the past 50 years, outdoor exposure sites have been developed in several countries with the objective of validating data obtained from laboratory testing for various combinations of reactive aggregates and SCM, as well as for determining long-term performance of specific mix designs. This paper reviews worldwide efforts regarding outdoor exposure site testing for ASR prevention.