THE IMPORTANCE OF CEMENT AND ITS PRODUCTS 
IN HOUSE BUILDING 
By J. M Haskell 
P ORTLAND cement is a dry almost impalpable 
green powder, sometimes blue, sometimes 
yellow in tone, which is sold in barrels or bags. 
It has the peculiar property that, when it is moisten¬ 
ed with water, it forms, on drying, an extremely hard 
mass, like stone. T his result is due to something 
more than the sort of hardening which takes place 
when powdered earth or clay is moistened and 
dries again into a hardened cake, for a chemical 
change has taken place through the action of the water 
upon the cement powder, and the dried product is 
something quite different chemically from the original 
powder. 
Cement 
Mortar 
The principal use to which the Port¬ 
land cements were originally put, and for 
which, indeed, they continue to be univer¬ 
sally employed, was in the making of mortar for 
brickwork and stone masonry. 
Cement mortar is, however, not composed of cement 
powder and water alone. This mixture is not used for 
several reasons. First, because the neat cement mor¬ 
tar, as it i$ termed, is so much harder than bricks or 
most building stones that it would not be good policy 
to use it, as nothing is really gained by having the ce¬ 
menting or binding material harder than the pieces of 
solid material out of which the masonry itself is 
constructed. Secondly, a mixture of cement and 
water alone, shrinks in volume as it dries, and 
cracks on drying owing to the contraction of the mass. 
For these two reasons the cement is usually mixed 
with some inert substance which, while increasing 
the volume of the mortar, and so preventing cracks 
on drying, reduces its strength to that of the materials 
it is to bind. The inert material usually employed 
for the purpose is clean sharp-grained river or pit 
sand; and as such sand is many times cheaper than 
THE VERSATILITY OF CEMENT 
Cement Age. 
2 35 
