_Cement._--In the early stages of construction the cement for the work
was obtained from the Associated Portland Cement Manufacturers, Limited,
of London, which supplied the "Pyramid" brand, from the Knight, Bevan,
and Sturges Works, but later the supply was obtained from a new factory
at Hidalgo, near Monterrey. The total quantity of Portland cement used
was 42,500 bbl. of "Pyramid" and 32,500 bbl. of "Hidalgo." The English
cement was tested for the Water-Works Company in London before shipment
and again at Monterrey, to conform to the British Standard
Specifications; the "Hidalgo" cement was required to pass the Standard
Specifications advocated by the Special Committee of the American
Society of Civil Engineers. The quality in each case was of the very
highest, no difficulties being experienced at any time.
_Sand and Rock._--One of the chief difficulties in connection with the
construction work in its initial stages was in procuring satisfactory
sand for the concrete. An investigation of the quality of all the
available sands in the neighborhood of Monterrey resulted in the
decision to use a manufactured sand obtained from the calcareous shales
in the foot-hills opposite the city, on the south side, and near the
site of one of the proposed reservoirs. A quarry was opened, and the raw
material was delivered by a gravity plane to a crushing plant, 230 m.
from the quarry and at a level about 50 m. lower.
The plant consisted of a No. 5 Austin gyratory rock-crusher, fitted with
elevators and revolving screens of various dimensions, driven by a
150-h.p. Erie steam engine; two sets of Traylor's heavy-duty crushing
rolls, one having 30 by 16-in. and the other 18 by 12-in. rolls; and a
Niagara sand disintegrator. This plant, except during a short period
when the requirements were beyond its capacity, was able to produce all
the sand and rock required for construction purposes. More than 40,000
tons of rock were quarried, the greater part of which was converted into
crushed stone and sand.
Table 2 gives the chemical analysis of the chief constituents of the
various sands examined.