The use of ready-mixed concrete (defined in BS 1926 as concrete delivered at the site in a plastic condition requiring no further treatment) has developed from its beginnings in the USA in 1913 to the stage where it now amounts to some 1.5 million cubic yards of concrete annually in the UK. This Digest briefly describes its advantages, such as savings in time and materials, but careful timing is required at the construction site, which must be ready to receive the concrete at a specific date and time.

Methods for the prediction of levels of daylight in buildings were reviewed in Digest no. 80, which included a brief account of the BRS protractors and the Waldram Diagram for the estimation of direct daylight and gave tables and data for judging the indirect or reflected daylight. The Building Research Station has now prepared tables that enable total daylight factors to be determined without the need for scale drawings. This Digest does not provide the tables (see National Building Studies, Special Report no.26), but gives an example to show their usefulness for calculating the sky components.