Investigation of road wearing surface systems for glue laminated softwood timber bridge decks

Cherry, Rebecca (2016) Investigation of road wearing surface systems for glue laminated softwood timber bridge decks. [USQ Project]

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Thousands of old timber bridges throughout Australia are in need of replacement and companies such as Hyne Timber are meeting this need with new innovative solutions such as modular glue laminated softwood timber bridges. These new products are bringing new needs of their own. This project aims to investigate road wearing surface systems for a longitudinally continuous modular bridge deck system constructed from glue laminated softwood timber, treated with the water based copper azole.

This dissertation has been completed in 3 main sections, firstly to research road wearing surface systems used on bridge decks throughout the world and select the best theoretical options for this application, secondly to investigate testing methods and develop a suitable testing regime and thirdly to carry out this testing on the best theoretical options and rank them based on the results. Discussions on the success of the testing methodology used have also been included.

The best theoretical options for the road wearing surface system that were put forward for testing included an epoxy (Omnigrip HF), polyurethane (Rhino Guard 2195), polyaspartic (Rhino ArmaFloor
500AU), epoxy modified acrylic resin (Street Bond 150) and C170 bitumen for a base comparison. These were selected by using a decision matrix based on the needs of the bridge user, bridge owner, regulatory authorities and bridge deck.

No standard test methods were found for this application, therefore a variety of tests and sample conditioning processes were researched with a focus on delamination and bond strength. Three standard tests and three sample conditioning processes were selected and modified to suit the glue laminated softwood timber bridge deck (GSTBD) application and are listed below.

. Delamination test: AS/NZS 4364:2010 Timber-Bond performance of structural adhesives section 7.6 Delamination resistance test.

. Shear Block Test: BD47/99 Design Manual for Roads and Bridges, Volume 2 Highway Structures Design.

. Pull Off Test: TRL Report 176 Laboratory Tests on High-Friction Surfaces for Highways, Appendix J Test Procedure for Tensile Adhesion (pull off test).

. Dry condition: based on other timber researchers work.

. Wet condition: AS/NZS 4364 Bond performance of structural adhesives – Vacuum pressure test.

. Delaminated condition: AS/NZS 4364: 2010, 7.6 Delamination resistance test.

All tests and sample conditioning processes were deemed successful providing quality data and comparisons to facilitate the aims of this project, except the delamination conditioning process. This process was used to replicate deterioration due to aging, however the results from the shear
block and pull off tests using these samples unexpectedly showed increased bond strengths. It is recommended that this conditioning process be further researched and improved. The test results revealed that the critical condition for all cases was wet with significant reduction in bond strength for both the shear block and pull off tests. All products outperformed the C170 bitumen in all sample conditions except for the epoxy modified acrylic resin (StreetBond 150) in wet condition.

The rankings determined in this dissertation were restricted to the results of the delamination and bond strength testing carried out and further research has been recommended to provide a more complete analysis and comparison of the systems.

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Item Type: USQ Project
Item Status: Live Archive
Additional Information: Bachelor of Engineering (Honours) Major Civil Engineering project
Faculty/School / Institute/Centre: Historic - Faculty of Health, Engineering and Sciences - School of Civil Engineering and Surveying (1 Jul 2013 - 31 Dec 2021)
Supervisors: Karunasena, Karu; Nataatmadja, Andreas
Date Deposited: 19 Jul 2017 01:53
Last Modified: 20 Jul 2017 00:05
Uncontrolled Keywords: road wearing surface systems; laminated softwood; bridge decks
Fields of Research (2008): 09 Engineering > 0905 Civil Engineering > 090503 Construction Materials
Fields of Research (2020): 40 ENGINEERING > 4005 Civil engineering > 400505 Construction materials

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