Bridge Expansion Joint for Bridges with Expansion Joints in Deck Slabs on Recycled Concrete Aggregate

Recycled concrete aggregate (RCA) is a sustainable fill material made from crushed concrete from demolished structures. RCA is used as a replacement for natural aggregate in bridge fills and subbase layers. RCA near existing expansion joints requires careful planning to minimize the effects on the joints. RCA properties include similar density to natural aggregate (1600-1900 kg/m3), lower strength than natural aggregate due to the attached mortar, and higher water absorption. RCA is used as a replacement for natural aggregate in areas where natural aggregate is scarce or expensive. RCA quality control requires testing of the RCA to verify that it meets the specified requirements. Particle size distribution, Los Angeles abrasion, and water absorption tests verify that the RCA is suitable for the intended application. The test results are compared with the specification requirements to verify that the RCA is performing as intended. Alkali-silica reaction (ASR) risk from RCA must be considered. RCA from concrete with reactive aggregates can cause ASR in new concrete if the RCA is used as a concrete aggregate. The ASR risk must be assessed by testing the RCA for reactive silica content. Settlement of RCA fills is similar to natural aggregate fills if the RCA is properly compacted. The settlement depends on the RCA density and the applied load. Settlement monitoring is recommended during and after RCA placement near existing joints. Post-installation inspection of existing expansion joints must verify that the RCA installation has not caused any damage. The inspection should check the joint gap width, the concrete edge beam condition, and the anchor bolt torque. Any damage must be repaired before the bridge is returned to service.