Allington Sluice Lock Gate, River Medway, Kent

A £2.7million Environment Agency project to renovate an ageing river sluice facility on the River Medway in Kent, has required the technical attributes of webercem five star repair concrete and the high-build properties of webercem HB30 mortar. 

The structural sluice repairs are now complete with new gates and operating systems installed, bringing the sluice performance up to standard. Reflecting the substantial improvement in the river water quality over recent years, a new fish and elver pass has been created to enable fish to travel further upstream in the clean waters. This has enhanced the habitat in upper sections of the Medway, whilst allowing migratory and freshwater fish free passage. 

Constructed in 1937 the Allington Sluice lock gate is the last on the River Medway before it becomes tidal. Although the sluice is not listed, the Environment Agency took a keen interest in the repair of the structure due to its location adjacent to the Museum of Kent. Areas of failed surface concrete that had spalled, due to 70 years of weathering, were repaired sympathetically to match the existing finishes. 

These areas were cleaned back to sound material with all loose material removed. The major repair areas required shuttering before pouring in the flowing recasting concrete. webercem five star repair concrete is a pre-blended cementitious material that conforms with BS EN 1504 : 3 as an R4 mortar and also with the Highways Agency specification BD 27/86. It contains non-reactive aggregates and low alkali content. This is a shrinkage-compensated, high-strength flowing repair concrete specifically designed for permanent structural repairs that delivers a compressive strength of 65N/mm² after 28 days.

Additional smaller damaged areas of the sluice structure have been improved with webercem HB30 repair mortar which is ideal for façade repairs where high compressive strength is not required. webercem HB30 is an acrylic-polymer modified, high-build façade repair mortar that complies with BS EN 1504 : 3 as an R3 mortar. Damaged areas were cut away and any steel re-enforcement was cleaned and coated with webercem keycoat prior to the application of the webercem HB30. This product has a unique shrinkage compensation system that ensures long-term dimensional stability. webercem HB30 is easy to apply with low permeability to water, carbon dioxide and chlorides.

Main contractor Jackson Civil Engineering of Maidstone, Kent, carried out the sluice gate works while Structural Renovations Ltd of Slough, Berkshire, carried out the concrete repairs in the overall reconstruction, renovation and modification programme of the main structure. The project was designed by Atkins for the Environment Agency, who also undertook site supervision during the renovation procedure. In addition to the repairs and fish pass, a new wheelchair access has been formed allowing cross river access at this point on the Medway.