ICE - Institution of Civil Engineers - Virtual Library

Bitumen, a constructional material used Since ancient times where occurring naturally, has, during the present century, become universally available as a product of the petroleum industry. Ita main use has been in roadwork, and much work and research have been carried out. Techniques developed for roadwork have been applied to hydraulic works in the past 20 years. Appropriate definitions, properties, four headings : tests, and types are set out in this Paper, and the hydraulic works are grouped under

• (1) breakwaters and groynes;

• (2) coast and estuary protection ;

• (3) protection and lining of rivers and inland waterways ;

• (4) linings for reservoirs and dams.

Works described include the grouting of the breakatem at the Hook of Holland and the novel construction of a harbour arm at Harhgen of sand protected only by the practice of three authorities. Sheet Bsphalt has also been used ; this material bitumenized sand. Coast protection by means of concrete blocks set in bitumen is commonly employed on the Continent for canal linings and in the United States of America for reservoirs. On the River Mississippi, protection is laid in mattress form given in two Appendices. Conclusions drawn are that hydraulic applications are likely or by dumping through water. Details of misturea employed, and some costs, are to increase and that, a greater knowledge is acquired, factors of safety and costs will be reduced.

Measurements of the coefficient of thermal expansion of different aggregates, and of concretes prepared from them with different cements, have been made over the temperature range 32F. to 104F.

The values for aggregates have been found to range from 2.1 to 6.5 l0^-6 per F. Siliceous materials have the highest coefficients, limestones the lowest, and igneous materials intermediate.

Concretes have values in the range 3.4 to 7.3 10^-6 per F. The magnitude of the coefficient of expansion of concrete depends largely on the aggregate used; concretes with siliceous aggregate have the highest values and those with limestone aggregate the lowest, whilst concretes with igneous aggregate have intermediate values.

The coefficient of thermal expansion of neat hydrated cement is higher than that of any aggregate measured. The richer mixes tend to have the higher thermal expansion but the order of difference is not high; the age of concrete has little effect on its thermal expansion.

The method of curing and the water content have only a small influence on the thermal expansion. Desiccated and water-saturated concretes have similar coefficients of expansion but the values are lower than that of partly-dry concrete.