Bridges

Transport for New South Wales (TfNSW) QA Specification B80 'Concrete work for Bridge' (TfNSW B80)10 has seen continual improvement over the years. These improvements adopted recent industry trends and new technologies including self-compacting concrete and high-workability concrete which has evolved from high slump concrete and concrete used for tremie placement, largely termed 'tremie' concrete. After the inclusion of self-compacting concrete in TfNSW B8010, a gap was recognized between high slump concrete and self-compacting concrete. This category appears to be informally filled-in by the traditional flowing concrete placed by tremie (aka 'tremie' concrete) which is normally used for deep foundations with varying quality of end-product. Some 'tremie' concrete mixes perform better than others. Within this space, a variant is used in the precast industry which is more related to self-compacting concrete but requiring limited compaction. To fill the specification gap, TfNSW, in collaboration with three major concrete suppliers in New South Wales, carried out laboratory trials to verify performance criteria through testing to assess fresh properties, placement process and assessment of hardened properties based on earlier research elsewhere.

This paper will discuss the:

• Modified test methods for assessing fresh properties
• Placement procedure trial to verify optimum degree of compaction
• Hardened and durability properties
• Adopted performance criteria in TfNSW B8010