THE Dubai-based branch of the UK’s Pitchmastic PmB has delivered a simple, quick, durable and quieter solution for a road rehabilitation project in Abu Dhabi emirate, which forms part of ongoing maintenance works by Al Ain Municipality.

The project involves the Dawoodi Bridge, a 55-m-long-span concrete arch bridge, which is being rejuvenated by removing the expansion joints in addition to road repairs and reconstruction of a new footway/median.

The existing joints on the bridge had failed due to various inadequacies and were causing deformation to the adjacent asphalt, and hence required an alternative expansion joint solution. Given its extensive track record in the region, Pitchmastic was approached to put forward its recommendations for the most appropriate joint system for the project.

The key criteria for the joint replacement solution were: durability at elevated temperatures; low noise in a sensitive residential area; quick to install and return to service time; and the ability to span joint widths of up to 1 m without needing to replace the existing asphalt.

Pitchmastic proposed its advanced nosing joint (ANJ), a surface-mounted nosing joint, comprising a pre-formed compression seal, bonded between high-strength nosings which are widely used in the UK and in other parts of the world on highway structures. “This type of joint is ideal for movement up to ±20 mm, is more durable than the current system and would not suffer the same symptoms as the problematic joint,” says a spokesman for Pitchmastic.

ANJ was chosen as it was seen as the ideal solution with benefits such as: its proven track record in the Middle East, local experience and reputation; international approvals and accreditations; warranty for installed materials; short lead times as project required an early start; limited return to service time as traffic disruption had to be kept to a minimum on this major artery in Al Ain; and durability in a heavily trafficked region with deck temperatures up to 70 deg C. Also the client was not happy with alternative materials due to installation times and noise issues.

The scheme comprised placement of crossover to enable traffic to be switched onto separate carriageway to allow works to proceed on closed lanes. Once these changes were implemented, the existing mechanical comb-type joint and bedding compounds were removed and the exposed joint was then prepared by scabbling.

Once the deck was cleaned and prepared, the existing asphalt was saw-cut to allow neat termination of the new ANJ joint, ready for the placement of the polystyrene joint filler and former. The ANJ resin mortar was mixed on site and then placed into the prepared trench in the carriageway and trowelled flush with the surfacing. To reduce hydraulic pressure, drainage was placed at the base of the joint and through the air gap. In order to increase slid resistance, an anti-skid finish was then be applied to the exposed surface of the joint. The final procedure was the installation of the elastomeric insert using compressed tongs.

The scheme was completed on time, opened to traffic 24 hours ahead of schedule, on budget to the client’s satisfaction.