Precast white concrete ceiling units at the Inland Revenue, Nottingham. Exposed 'architectural' concrete has been making a comeback after a considerable period out of favour. Much knowledge was lost during that period and it is hard to find experienced designers and contractors. A new generation will re-learn and take advantage of later developments such as the use of pigments, controlled-permeability formwork systems, and better understanding of the effect of curing on micro structure and hence weathering.
High-strength concrete at Taikoo Shing Cityplaza. The strength of concrete in buildings is increasing and 50-60 N/mm2 is fairly commonly used compared with 35-40 N/mm2, which is the norm, itself a big improvement on the 20-30 N/mm2 of 30 years ago. It is possible to achieve 100-120 N/mm2 on a ready-mix scale, but there is no demand in the uk because we do not generally build tall buildings. Maybe the cost equation will change. A possible inhibition is that BS 8110 only refers to concrete up to 60 N/mm2, but guidance on higher strengths is now available. Strengths up to 400 N/mm2 can be achieved in workshop conditions.
The macro defect-free concrete spring demonstrates the strength properties of this new form of cement.