Alkali-silica reaction (ASR) and freezing and thawing (F/T) cause premature deterioration and reduce the service life of concrete structures, and both are difficult to mitigate in existing concrete pavements once deterioration occurs. The objective of this research program was to evaluate the efficacy of silane surface treatments used to reduce the moisture state of concrete pavements, thereby reducing further deterioration from ASR and F/T and increasing the remaining useful life of the pavement. The pavement test section evaluated contained a borderline-reactive fine aggregate and marginal air entrainment. The efficacy of silane was evaluated by instrumenting a pavement test section with devices for monitoring strain and internal RH. Core samples were extracted before and after treatment. The core samples were evaluated using the damage rating index (DRI). Results indicate silane may reduce the rate of deterioration in the concrete pavement compared to untreated control sections.

Producing concrete requires considerable quantities of natural aggregates, and contributes to large amounts of solid waste in both production and when removed from service. With many structures reaching the end of their service life, a means of concrete disposal is needed that is both practical and eco-friendly. Reusing concrete waste as recycled concrete aggregate (RCA) in new concrete is a promising solution. However, the current use of RCA is generally limited to backfill and road base. Additionally, alkali-silica reaction (ASR) can pose a substantial obstacle to highly durable concrete and with limited research on ASR behavior in RCA, effective design recommendations are lacking. Current methods of ASR mitigation depend on experimental testing for aggregate classification. Therefore, a multi-laboratory study was done using ASTM C1260 with nine laboratories and 10 operators to determine within- and between-laboratory variation on ASR expansions. The result of this investigation suggests a small change to the existing precision statements of ASTM C1260 to allow the standard to incorporate RCA into the accelerated mortar bar test (AMBT). In addition, testing revealed that expansions using RCA and natural aggregates produced nonreactive or moderately reactive mortar mixtures far more frequently than highly reactive mixtures.

Alkali-silica reaction (ASR) and reinforcement corrosion are wellknown deterioration mechanisms in concrete structures. This research investigates how ASR affects corrosion in reinforced concrete specimens. Concrete specimens containing aggregate susceptible to ASR (reactive) and aggregate not susceptible to ASR (nonreactive) were cast. Expansion of the specimens, corrosion potential, macrocell current, and chloride diffusivity were measured for each specimen until the embedded reinforcement began to actively corrode. Scanning electron microscopy (SEM) results indicate that ASR gel can fill the interfacial transition zone (ITZ) and cracks, which can reduce the transport of the chlorides in concrete. The presence of ASR gel at the HCP-steel interface likely reduces the pH at the interface, which can reduce the critical chloride threshold level (CT). The results indicate that ASR expansion does not significantly influence the time to corrosion initiation of reinforced concrete systems for laboratory specimens exposed to wetting/drying cycles at 100°F (38°C).

The long-term effect of supplementary cementitious materials (SCMs) on alkali-carbonate reaction was evaluated using the concrete prism test for up to 10 years. None of the SCMs showed complete mitigation effects, although some types were more effective than others in reducing the expansion. Blending 10% reactive with 90% nonreactive aggregates was effective in meeting the 0.040% expansion limit at 1 year; however, the expansion was 0.074% after 10 years at room temperature. The chemical method for evaluating aggregate was found to give false negative or underestimate the potential expansion of blends of reactive and nonreactive aggregates. The use of SCMs with blends of aggregates that marginally meet the 1-year expansion limit provides some benefits in reducing the expansion at later ages. The concrete microbar test provides good correlations with the concrete prism test containing 100% reactive aggregates with and without SCM, but underestimates the expansion of blends of aggregates.