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.
TABLE 2.—Analysis Of Sands In The Neighborhood Of Monterrey.
| No. | Location. | Percentage of silica (absolute), SiO2 | Percentage of alumina, Al2O3 | Percentage of sesquioxide, Fe2O3 | Percentage of lime carbonate, CaCO3 |
| 1. | Arroyo Seco, near brickyard at Monterrey | 60.10 | 17.95 | 2.89 | 8.01 |
| 2. | Arroyo Seco, near brickyard at Monterrey, No. 2 | 42.92 | 14.26 | 4.66 | 34.58 |
| 3. | Near Garcia Station, Mexican National R. R., Chiquito River, No. 1 | 50.22 | 9.72 | 1.44 | 34.62 |
| 4. | Near Garcia Station. Mexican National R. R., Chiquito River, No. 2 | 48.7 | 4.92 | 8.28 | 35.43 |
| 5. | San Luis Potosí | 85.02 | 5.00 | 7.38 | 2.21 |
| 6. | Topo Grande, Pesquería River | 40.20 | 5.15 | 4.25 | 46.50 |
| 7. | Hornos, near Torreón | 77.9 | 13.1 | 2.4 | 4.9 |
| 8. | Salinas River, at Salinas | 41.5 | 5.7 | 1.4 | 48.2 |
| 9. | Pits near Caballeros, on Tampico Branch of Mexican Central R. R. | 73.4 | 5.6 | 4.4 | 10.1 |
| 10. | Santa Catarina River,
near San Geronimo (washed sand) | 12.40 | 2.06 | 1.14 | 81.70 |
| 11. | Santa Catarina River, at Monterrey | 17.4 | 2.50 | 2.00 | 77.00 |
| 12. | Composition of rock, quarry in foot-hills opposite Monterrey, Monterrey Water-Works and Sewer Company's property | 40.44 | 15.70 | 2.20 | 34.30 |
| 13. | Manufactured sand from above quarry (run of crusher) | 51.80 | 12.14 | 8.7 | 32.6 |
The chief sands used for ordinary building purposes in Monterrey are Nos. 10 and 11, which are procured from the bed of the Santa Catarina River. As these sands contain large proportions of lime carbonates, which make them very undesirable for important structures, their use was limited to relatively unimportant work. The best sands procurable were Nos. 5 and 9, but the long distance of the pits from Monterrey, and consequently the heavy freight rate, made their use prohibitive on economical grounds. The best of the available sands, although it was very fine, was No. 7, from Hornos, near Torreon, as it could be depended on for uniformity and could be obtained f. o. b. cars at Monterrey for 3.18[5] pesos per ton.
[5] All costs given in this paper are in Mexican pesos, one peso being equivalent to 50 cents in U. S. currency.
The bulk of the sand and crushed rock used was similar to Nos. 12 and 13, and reference to the cement sand tests in Table 3, will show that the manufactured sands gave very satisfactory results.
Table 3 gives the average tests made with the "Hidalgo" cement and various sands, alone and in combination, for the purpose of obtaining comparative results; the mixtures tested were composed of 3 parts of sand to 1 of cement.
TABLE 3.—Tests Of "Hidalgo" Cement With Various Sands.
| Sand. | At 7 days. | At 28 days. | ||
| Ottawa (Standard) | 305 | lb. | 414 | lb. |
| Monterrey, 11⁄2 parts,Hornos, 11⁄2 parts | 188 | " | 313 | " |
| Monterrey | 253 | " | 365 | " |
| Hornos | 202 | " | 301 | " |
| Manufactured sand, Company's crusher | 372 | " | 566 | " |
| Hornos, 2 parts,Crusher sand, 1 part | 231 | " | 352 | " |
| Hornos, 11⁄2 parts,Crusher sand, 11⁄2 parts | 265 | " | 346 | " |
| Hornos, 1 part,Crusher sand, 2 parts | 248 | " | 328 | " |