Cement production is the manufacture of hydraulic cement from rock usually quarried by the manufacturer. The principal cement product is Portland cement, patented in England in 1824 and originally used as a substitute for lime mortar, but small quantities of natural cement and pozzolana are also manufactured. Limestone and clay, or materials containing the same mineral constituents, are mixed in definite proportions to produce chemical reactions during a burning process. The finished product is an extremely fine dry powder, which when wet will become hard. Certain regions of Texas, particularly where the Edwards and other limestones outcrop, are ideal for cement production. Cretaceous limestones and shales or clays suitable as raw materials for Portland cement can be found in the Blackland Prairies, Grand Prairies, Edwards Plateau, and Trans-Pecos areas of Texas. Iron oxide, also required for cement production, is found in iron-ore deposits in East Texas. Gypsum, used as a retarder in cement, is available in north central Texas, Central Texas, and the Trans-Pecos region. Along the Gulf Coast, cement producers have used oyster shell for calcium carbonate, while a Texas High Plains cement plant near Amarillo has used impure caliche as its chief raw material.
In 1882 there were two cement factories in operation in San Antonio and one in Austin. As late as 1909 Texas had only three factories, but between 1909 and 1925 cement manufacturing in Texas showed an increase of 185 percent, and the production of cement was the state's twelfth-ranked industry. Cement production in 1929 reached a peak of 7,369,000 barrels, fell to 2,973,000 barrels in 1933, and rose to 8,036,515 barrels from ten plants in 1945, when Texas was the second-largest producer and consumer of cement in the United States. The principal use of cement is in concrete and reinforced concrete. After World War II one of the large-scale uses for cement in Texas was the manufacture of concrete blocks for construction; hundreds of small plants sprang up all over Texas to produce large, hollow building blocks from a semidry mixture of cement and fine aggregate, shaped in a steel or cast-iron mold by either tamping or vibration. For a time these plants produced for a market in which there was a great scarcity of other types of material-and for that reason showed immense profits. As the construction industry stabilized after the war, many of these small cement plants were shut down, while others adjusted to smaller profits and more regular production. But the concrete building block had become a prominent part of postwar Texas architecture.
By 1954 Portland cement production totaled 21,350,000 barrels valued at $53,500,000. Portland cement ranked next to petroleum minerals in 1964, when its production increased to 29,600,000 barrels valued at $94,128,000. In the same year masonry cement production totaled 950,000 barrels valued at $2,917,000. Figures for 1966 indicated that cement production for that year was 2 percent higher than the preceding year, with Portland cement production exceeding 31,000,000 barrels valued at $100,166,000, and masonry cement production decreasing to a total of 922,000 barrels valued at $3,013,000.
In 1970 Portland cement production was over 35,000,000 barrels valued at more than $107 million. Masonry cement production was 955,000 barrels valued at over $3 million. In that year Texas had nineteen cement producers located in Bexar, Dallas, Ector, Ellis, El Paso, Harris, Johnson, McLennan, Nolan, Orange, Potter, and Tarrant counties. By 1976 thirteen companies were operating eighteen cement plants in twelve counties. By 1978 construction materials were in short supply, deliveries were delayed, and plans were announced to build new plants in Comal and Williamson counties. With a value of $393 million, total production in that year made cement the state's top-value construction material. Production of both Portland and masonry cement continued to increase, reaching a high in the mid-1980s, when 10,242,000 short tons of Portland cement valued at over $532 million were produced, along with 310,000 short tons of masonry cement valued at over $22 million. By the late 1980s Texas was the nation's leading producer and consumer of Portland cement, which was then being prepared at thirteen plants in Bexar, Comal, Dallas, Ector, Ellis, Hays, McLennan, Nolan, and Potter counties. Revenues from the state cement tax grew from almost $3 million in 1970 to almost $6 million by 1987. Foreign exports of building cement in 1987 totaled 1,882 short tons, and domestic shipments totaled 332,534 short tons. In addition, Texas imported 745,349 short tons of foreign building cement and had domestic receipts of 202,323. Thereafter, production of both Portland and masonry cement slowly declined. In 1990 Texas producers manufactured 8,000,000 short tons of Portland cement valued at $320 million, and 145,000 short tons of masonry cement valued at almost $12 million.