The Use of Gunite as a Structural Material A Survey of Developments, 1930 -1955

ALL structural engineers are familiar with the simple structure that is in fact difficult to design in precise terms because of uncertainties in the assumptions on which any accurate analysis of stresses can be based. The road is a notable example of this because the analysis of stresses in a slab supported on a foundation that is at best only semi-elastic is not an easy matter and, in addition, because stresses due to temperature changes are almost as important as those due to the applied loading. Another factor is that structural failure in roads is seldom a definite phenomenon. It takes place over a considerable period of time and can often be counteracted by increased maintenance work or resurfacing. Therefore, there is not the same need as in other structures to allow for a substantial “factor of safety,” the design being a compromise between first cost and length of life. For a stress analysis to be of much value in these circumstances it must achieve a considerable degree of accuracy. A. R. Collins

THIS paper gives a short account of the application of soil mechanics to road design. The principles by which wheel loads are transmitted to and resisted by the subgrade are discussed. Several methods of pavement design are reviewed, in which the necessary pavement thickness is related to the soil properties. Some experimental results are given to show the correlation of certain soil properties and their variation with moisture content. Finally brief reference is made to cement stabilisation. P. L. Capper

THIS subject covers so much of the whole art and science of road-malting that its proper treatment in a relatively short paper is not easily decided. In the present instance an attempt has been made to give a brief review of its nature, development and scope in the hope that such information, although not novel, can form the background for a more detailed discussion. A.W. Jarman