Bridge Expansion Joint for Bridges with Expansion Joints in Deck Slabs on Compaction Grouting

Compaction grouting is a ground improvement technique that densifies loose soils by injecting stiff grout under pressure. The grout displaces and compacts the surrounding soil, increasing its density and bearing capacity. Compaction grouting near existing expansion joints requires careful planning to minimize the effects on the joints. Compaction grouting process involves drilling a hole into the ground, inserting a grout pipe, and injecting stiff grout under pressure. The grout forms a bulb that displaces and compacts the surrounding soil. The process is repeated at multiple depths to treat the full depth of the loose soil. Ground heave from compaction grouting can occur when the grout volume is too large or the injection pressure is too high. Ground heave can affect adjacent expansion joints by changing the joint gap width. Ground heave monitoring is recommended during compaction grouting near existing joints. Grout pressure control during compaction grouting is critical for preventing ground heave. The grout pressure must be monitored and controlled to prevent it from exceeding the design value. The grout volume must also be monitored to prevent over-injection. Post-grouting inspection of existing expansion joints must verify that the compaction grouting 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. Compaction grouting effectiveness is verified by comparing the soil properties before and after grouting. Standard penetration tests (SPT) or cone penetration tests (CPT) are performed before and after grouting to measure the improvement in soil density. The test results are compared with the design requirements to verify that the grouting has achieved the required improvement.