Advantages of Reinforced Concrete

From these experiments and those made by other investigators, and from the examination of structures, which have been taken apart, it may be concluded that concrete, when properly mixed and placed, gives the best protection yet discovered for the steel embedded in it, and that concrete may be safely used in all structures except where the chemical action would affect the concrete itself.

Durability.

There is scarcely any class of manufacture which is not now being carried on in a reinforced concrete building. It is adapt able to any weight of loading, to high speed and heavy machinery, as well as to light machine tools, and to almost any style of design.

Recent scientific experiments, as well as act ual experience, are favorable to the use of con crete under repeated and vibrating loads.

The use of concrete in brackets for support ing crane-runs is an interesting example of se vere application of loading. Several concrete buildings in San Francisco withstood the shock of the earthquake, while those around them of brick and stone and wood were destroyed.

While most materials tend to rust or decay with time, concrete under proper conditions con tinues to increase in strength for months or even for years.

Concrete expands and contracts with changes of temperature. Its coefficient of expansion— that is, its expansion in a unit-length for each degree of increase in temperature—is almost identical with that of steel, and on this account there is no tendency of the steel to separate from the concrete, and they act together under all As in building with other materials,, provision must be made, in long walls or other surfaces, for the expansion and contraction due to temperature, by placing occasional expansion joints or by adding extra steel. In factories of

ordinary size, no special provision need be made, as the regular steel reinforcement will prevent cracking.

Stiffness. A reinforced concrete building really resembles a structure carved out of a single block of solid rock. It is monolithic, or of one piece throughout. The beams and girders are continuous from side to side and from end to end of the building, while even the floor slab itself forms a part of the beams, and the columns are also either coincident with them or else tied to them by their vertical steel rods.

All this accounts for the extraordinary stiff ness and solidity of a reinforced concrete struc ture, and puts it into a different class from tim ber construction, where positive joints occur over every column; and even from steel con struction, in which the deflection is greater.