STATE GEOLOGISH. 63 
CHAPTER III. 
THE USES OF CEMENT IN CONCRETE. 
Cement was first extensively used to make concrete for foundations 
of large masonry structures. It may be well at this point to define con- 
crete. Concrete is formed by a mixture of cement or lime mortar with 
any aggregate such as gravel, broken stone, cinders, or broken brick, the 
whole forming a solid conglomerate mass of stone. That formed with 
a cement mortar is sometimes called “beton.” In this article, in speaking 
of concrete, that formed from natural or Portland cement will be under- 
stood unless otherwise stated in the immediate paragraph. 
FOOTINGS AND FOUNDATIONS. 
Concrete becomes of particular importance in footings and foundation 
work. In all properly designed structures the weight of the structure 
should be so distributed upon the foundation soil, that no unusual pres- 
sures can be developed. Undue pressure causes unequal settlement 
and therefore produces excessive and unknown strains within the various 
portions of the structure. With the usual rough stone masonry put in 
place for footing courses, it is almost impossible to obtain foundations 
having equal strength at all points and which transfer the weight of the 
structure uniformly to the soil beneath. On the other hand concrete can 
be placed in position by unskilled labor, with reasonable supervision, and 
become a homogeneous monolithic mass, capable of transferring the weight 
of the building very evenly to the subsoil foundation. 
One important advantage which concrete has over stone masonry for 
foundations is in the rapidity and cheapness with which it can be placed in 
position. Masons must have room in which to work, and space for surplus 
material, mortar boards, etc. But few masons can be economically em- 
ployed upon the foundations of even large structures. With concrete foun- 
dations, the excavation can be limited to the size of the foundation. The 
material may be stored at any convenient place, mixed there and conveyed 
to the foundation trench in wheelbarrows, by derrick and box, belt con- 
veyor, inclined chutes, or by any of the many approved economical 
methods. After being dumped into place, as many men as the work 
requires may be used to properly dispose and ram the material into place. 
