Durability of Exposed Aggregate Pavement

In recent years, exposed aggregate concrete has been used increasingly for the construction of the top surface of concrete pavement in Germany. Following placement, the fresh concrete surface is usually sprayed with a combination of a retarder and a curing agent (first curing). Depending on weather conditions and concrete composition, the surface mortar is brushed off after 8 to 24 hours to expose the coarse aggregate structure. A curing agent is then applied to prevent the concrete surface drying (second curing). The effect of different first and second curing methods on the durability of exposed aggregate concrete pavement was investigated. Durability was characterized by the capillary uptake of water, freeze-thaw deicing salt resistance and a laboratory test simulating field conditions. The capillary uptake of water showed that both first and second curing affect concrete microstructure, second curing having a larger effect than first curing. No effect of first curing on freeze-thaw deicing salt resistance was found for exposed aggregate concrete. Good quality second curing was observed to reduce scaling and abrasion due to field conditions.