TARMAC.COM

TALL BUILDING CONSTRUCTION BENEFITING FROM INNOVATIVE SPECIAL CONCRETES

With the volume of available prime development space in our major cities continuing to decline at a time when the demand for new residential and commercial space is growing, the solution for a high proportion of developers is multi-storey buildings.

A trend for taller structures of 40 storeys and above requires the use of innovative materials with significantly higher compressive strengths, with developers often specifying high strength and high early strength concrete for the vertical elements of new tall buildings.

The use of these special concretes can extend beyond merely the vertical components of a new build, yet the materials only tend to be adopted if the schedule of a project begins to slip.

If specified from the outset however, these types of products can maximise the usable space within a structure, as well as generate savings and have a positive effect on productivity and the overall build programme.

Ignacio Escobar, National Engineering Manager

TARMAC.COM

BENEFICIAL OUTCOMESLaying thinner, stronger material for both the walls and floors not only has a beneficial outcome on the light in the subsequent rooms, available space and the external envelope, but also makes the building weigh less. Cost savings can be achieved as a consequence of smaller foundations and a reduced façade surface, because less material is needed for construction than when using traditional concrete.

The construction industry therefore has a significant opportunity to deliver commercial value through the increased use of special concrete solutions for tall buildings.

This view has been backed up with independent research conducted by professional services firm Arup, which reviewed both in-situ concrete and composite-steel framed multi-storey building structures. The study helped to pinpoint the ways that two concrete innovations – self-compacting and high early strength concretes – are able to add value to projects in these types of construction for residential and commercial buildings.

By reviewing two real-world projects – one a 21-storey steel-framed commercial building with reinforced concrete (RC) cores and composite slabs and the other a 16-storey RC flat slab residential building – factual information was analysed to identify the potential benefits of using these innovative concrete solutions.

EFFICIENCY SAVINGSIt was clear from the results that there are significant programme savings to be achieved for composite slabs and shear cores for steel-framed commercial buildings. Efficiency savings can be realised as the material is able to be poured more quickly and requires less finishing than a traditional standard mix. It was calculated that a building owner could make an overall cost saving of approximately £268,000, with the additional benefit that the faster construction also allows earlier access for follow on trades, both above and beneath the slab.

For a concrete-framed residential building, the combined savings on materials, plant and labour with the reduced external envelope totals £391,000, representing a cost saving of 8.4 per cent.

Furthermore, if the concrete cores for these types of buildings are on the critical path and constructed using jump-form, further programme reductions can be achieved. Using high early strength concrete in this way can potentially offer a 40 per cent time saving for the core construction, translating into a five per cent reduction to the total overall programme.

Consideration of special concretes at the design and construction stages can clearly be beneficial. Being able to reduce element sizes, speed up construction and facilitate an easy placement of the product at height by using special concretes all create project cost savings.

The specification of innovative special concretes when on the critical path is essential for boosting productivity, cutting build timescales, reducing materials, maximising space and ultimately delivering financial savings. We need to ensure that we are building smarter and more productively in order to create a new skyline that showcases tall buildings.