BATUKAWA BRIDGE EXTENSION: EXPANSION JOINT INTRODUCTION
Since installation, the expansion joints are attacked not only by natural elements such as water, dust, dirt, ultraviolet rays, and ozone, but also elements introduced by humans such as deicing chemicals, or traffic impacts. Each possible defect is a contributing factor to deterioration. The performance in service of the common type of bridge joints has been studied and present in report published by The New England Transportation Consortium June 29, 2006. The factors that are considered important in influencing the performance of bridge of bridge joints are:
1. Structural movement at the joints 2. Traffic over the joint
3. Bond and anchorage 4. Conditions of the substrate
5. Detritus, foreign matter and corrosion
6. Weather & temperature
7. Site Preparation and workmanship The existing Batukawa Bridge was facing the same problem like other bridges. The existing expansion joint show failure and bring discomfort able to the road user. The damaged of the exiting expansion joint had reminded us for the selection of the joint for the extension bridges. OBSERVATION
The existing expansion joint was elastomeric joints which consist of the prefabricated rubber reinforced or metal running plate with the flexible strip seal to accommodate deck movement. Then running Plate Bridge is fixed to the bridge decks over the joint gap using the anchorage system. It holds down by the bolts or anchor bars.
The photo shows the defects existing expansion joint at the Batukawa Side (Abutment A)
1. The anchorage system, cap covering the holding bolts splits out. Protruding Bolts exposed as traffic hazard.
2. The elastomeric plank torn and splits after damaged or hardened seal. 3. Nosing crack and separation of the nosing from premix surfacing
1 2 3 1 2 Bridge side Land side
This photo shows the defects existing expansion joint at the Kuching Side (Abutment B)
1. The protruding Bolts exposed as traffic hazard, cap covering the holding bolts splits out. 2. Nosing crack and separation of the nosing from premix surfacing
2 1 2 1 1 2 Land side Bridge side
COMMENTS
The defects found over the expansion joint are mainly on the anchorage system over the bolt connection and the nosing cracking. The separation of concrete and the premix also kind of failure due to the poor workmanship. Material used deformed under weather and temperature. From the observation, the damage of the anchorage system at the land side was more serious compared to the bridge side. The bolts covering was splits off and the road user experience the ungrateful drive when crossing the expansion joint. It might caused by the difference level between the land side and the bridge side. The condition of substrate might change after long term settlement which in different rate.
Traffic loading also leads the expansion joint to failure. The rapid increase of traffic of the user especially heavy vehicle like Lorries and trailers. The traffic load had been increase to support the fast development of the residential area.
The elastomeric plank of the expansion joint which split off at abutment A, Batukawa side shows that the “rubber reinforced” material of the elastomeric plank happening as the deformation due to long-term expose to the hot weather and temperature. The rubber seems to be hardened after oxidized. It tears along the alignment of the expansion joint.
The oxidized elastomeric tear off from the expansion joint.
The existing expansion joints had been study to improve the selection of joint for the extension joint and the repair work for the package B which included replace / repair of the existing bridge.
The selection if the expansion joint remain as the preliminary design of the shop drawing but the installation method of the Multiflex expansion joint was modified for the joint with the following purpose.
1. To prevent the direct horizontal impact on the joint edge and causing damage. The placing of the joint and the transition strip have to be slowly taper to the asphstic road surface by following the road finish profile.
2. To hook the bolts to the desk slab reinforcement as the strengthening of the anchor bolt.
The method statement for installation is as below:
Step 1
1. Reserved the transition strip at the Abutment and Bridge side without concrete casting 2. Place the expansion joint following the finish road profile with the block out.
Step 2
1. Tape the edge of the multiflex joint pieces and premix the surface with masking tape along the entire joint length.
2. Prime the entire joint transition block out prior to the pouring of the Megareco Elastomeric concrete together with the desk slab and abutment reserved area. 3. Make sure the joint transition strip block out after priming is clean of dirt or debris.
Step 3
1. Mix the correct proportion of Megareco Elastomeric Concrete binder Part A and Part B hardener into a pail and stir thoroughly.
2. Pour in sand and aggregates into the rotation mixer and blow dry with hot lance to remove excess moisture.
3. After that pour in the stirred binder mixture into mixer and mix thoroughly until a uniform blackish mixture before pouring into block out.
Step 4
1. Pour the mixed Megareco elastomeric concrete material into the joint block out.
2. Compacted and trowel the material into the gap of the joint transition block- out with the use of spade and trowel tools until a level surface is achieve with premix surface.
Step 5
1. Filled up the bolts holes with sealant after final tightening of the nuts.
2. Check that the Megareco Elastomeric concrete transition material had hardened. 3. Clean and tidy the area around the joints after completion
