Fosroc were approached by Breedon Ready Mixed Concrete to supply an admixture suitable for large concrete pours on the new Aberdeen highways works. The project includes two significant focal point bridges over the rivers Dee and Don.
With the bridge abutment structures being heavily reinforced, the ability for vibration would be limited and with large pours in excess of 200m3 the requirement for a high flow concrete allowing good compaction was a necessity. The mix had been designed for high strength and durability, a cement content of 550kg per m3 with low water cement ratios.
Fosroc have developed many project specific admixtures over the years, offering solutions to many high profile projects serviced through our global network of manufacturing units and highly qualified support people.
Auramix 740SR developed for extended workability retention went through rigorous testing before being chosen as the admixture of choice. With such high cement contents and the requirement for a flowable concrete, a higher than normal dosage of admixture would be needed. We have found over the years that this level of admixture would normally contribute to an extremely viscous and volatile concrete giving its own problems in control and placing. Following trials Auramix 740SR was dosed at 1% per the weight of cement offering flows in excess of 700mm, eliminating the need for vibration for compaction.
Installation on the project went smoothly, offering benefits both on manpower and in speed of placing. The extended workability benefits offered by using Auramix 740SR proved invaluable both in the radials traveled to site and in the compaction of the finished structure. The low viscous concrete was easily placed with less manpower than would normally be associated with this type of pour.