Alkali-Silica Reactivity of Aggregates from Airfield Pavements and Its Correlation with Historic Field Performance

The Federal Highway Administration (FHWA) has recently introduced a new reactivity index (RI) to predict alkali–silica reaction (ASR). This novel chemical reactivity index can be used to develop two different types of screening tests to evaluate aggregates alone or job mix designs. The objective of the study presented in this paper was to explore the applicability of the new RI for ASR screening in aggregates used in the construction of airport facilities. The alkali–silica reactivity of the aggregates selected in this study varied from nonreactive to slowly reactive based on their historic field records. The ASR susceptibility of these aggregates was determined using two different testing protocols based on the RI. The first protocol, known as the Turner-Fairbank ASR susceptibility test (T-FAST), was used to determine the alkali–silica reactivity of the aggregates alone. The second protocol, also based on the RI, was applied to determine the ASR susceptibility of the job mix designs. The results of these two new ASR screening protocols were compared against those obtained using the Advisory Circular 150/5370-10H Item P-501, and ultimately with the historical field performance of the aggregates. The new RI accurately identified a slow reactive aggregate that triggered ASR deterioration in the concrete pavement and other structures in Denver International Airport (DEN) after 25 years of service life.