Case Study

Route One Operatives installed Ennis Flint’s Prismo Thormajoint® BJ 200 ST to the A82 Ballachulish Bridge. This is a combination of an elastomer modified binder BJ200 and a carefully selected aggregate that provides strength and flexibility.

Thormajoint® is a proven bridge expansion joint, providing effectiveness and reliability. Ennis-Flint’s bituminous bridge expansion joints have been developed to provide a reliable, weather resistant joint that is practically indistinguishable from the road surface.

On the first day, works were carried out under lane closures. Our operatives, along with a representative from Freyssinet marked out the joints ready for saw cutting. The surfacing and bridge deck waterproofing was completely removed by saw-cutting and jack hammering on the southbound carriageway to expose the deck as a clean join to the asphalt is essential. The traffic management was then switched and this process was repeated on the northbound carriageway.
Following the completion of the saw cutting, the main contractor halted the works over traffic management clashes between our works and the works Freyssinet were carrying out at the other end of the bridge. Our workforce, along with the main contractor and Freyssinet discussed how they could work around the issue and decided to implement a full closure to encompass all aspects of the works.

On day 2, 11.2m of APJ was installed into the carriageway. This was done by cleaning out the recess and the expansion gap and preparing it with a hot compressed air lance to warm the surrounding surfaces. The expansion gap was then caulked using Thormafoam. The recess was tanked with hot BJ200 binder to seal the joint and improve the adhesion of the joint to the asphalt. The mild steel APJ plates were then installed over the gap. Stone heated to 150°c – 190°c was poured into the joint and then flooded with binder heated to the correct temperature and repeated until the joint was within 25mm of the surface. The thormajoint pre-mix layer was applied and compacted. It was finally sealed using BJ200.

Following this, Freyssinet dug out 50mm in the concrete verges and we extended the plug to the parapet on both sides. The northbound kerbs were reinstated, an air gap cut and filled with polysulphide. The southbound kerbs were formed out of the plug material.

The drainage detail on the drawings couldn’t be installed due to the depth of the joint on the northbound carriageway. This prompted another discussion with ourselves, Freyssinet and the main contractor and it was agreed that a cross drainage would be installed.

On the final day of the works, the Dynagrip 1.4-2mm dressing stone was applied. This aggregate has excellent impact, crushing, abrasion and skid value.

• Ennis Flint Prismo Thormajoint BJ 200 ST
• Worked collaboratively with Freyssinet and the main contractor to overcome TM and drainage issues.
• Completed on programme despite weather conditions.