BASF assist record-breaking concrete pour at The Shard
The contrast could hardly be greater: just a stone's throw from venerable old London Bridge, a gigantic futuristic skyscraper dominates the city's skyline. Dubbed "The Shard", it has an all-glass facade and is shaped like a steep pyramid. At a height of 310 metres, it is Western Europe's tallest building.
Completed in July 2012, the building was constructed using specially matched concrete admixtures from BASF from the foundations up. Here admixtures were used to facilitate a single concrete pour of almost 5,500 cubic metres – a record in the history of British construction.
Record set on the weekend
"The entire foundation slab was poured on a single weekend, because causing prolonged traffic snarl-ups with construction vehicles right in the middle of London was out of the question," explains Brian Williams, Southern Regional Sales Manager BASF Admixture Systems UK.
"To ensure that the densely packed steel reinforcement bars at the base of the slab were coated quickly and completely within this short time, the concrete had to be particularly flowable - clearly a job for BASF's specially developed Glenium® Sky." A further advantage of this admixture in high-rise construction is that it enables concrete to be pumped to a height of 300 metres without problems.
Stable and homogeneous concrete
Another major challenge was the immense amount of concrete needed to cast the foundation. As concrete generates heat while setting, a lot of concrete means a lot of heat. The hotter concrete becomes, the faster it sets. This can create a serious problem: if the first layers poured set too quickly, the following layers cannot bond with them properly. The resulting concrete is neither homogeneous nor stable enough. At The Shard, BASF's Pozzolith® admixture prevented the concrete from setting too soon, thereby ensuring high quality, homogeneous concrete.
This high quality concrete also ensures that the construction material can cope with the huge pressure generated by the enormous height of the tower. Thanks to Glenium® admixtures, the concrete withstands a pressure equivalent to the weight of a small car resting on an area the size of a big toe. This outstanding strength ensures a long lifetime for the concrete structure and makes for sustainable building usage.