A simple apparatus, measuring the volume of chips required to cover a standard area, gives the spread ratio directly on a dipstick reading and allows automatically for the shape of the chips. The spray rate for bitumen is determined jointly from the measured voids between chips, the nature and intensity of traffic and the texture of the existing road surface. A nomogram obviates calculations. To allow for contraction and evaporation, a table of application factors is given.
Reinforced concrete water-retaining structures are designed to be non-cracking but it is doubtful whether the provisions of CP 2007 ensure this. If a structure does crack it is desirable that the width of crack will not exceed a safe value, i.e. a value which will not give rise to harmful corrosion of the reinforcement or excessive leakage. Small cracks tend to be self-healing if the environment is sufficiently moist. Theoretical and experimental investigations show that crack-width in an axially-tensioned centrally-reinforced prism is directly proportional to the stress in the steel at the crack, to the area of surrounding concrete, arid inversely proportional to the sum of the perimeter of the bars.
The paper descriptionbed some general aspects relating to civil engineering construction, including temporary and ancillary works. An account was given of the methods of water control during construction and of concrete production. Brief descriptionptions were given concerning the organization and layout of plant and services, design criteria, control of materials, accommodation and labour with reference to environment and health.