PRELIMINARY ASSESSMENT OF PENNSYLVANIA DOLOSTONES FOR POTENTIAL AS NATURAL CEMENTS

Hydraulic, or water-setting, cement is a vital component in construction. Most modern construction needs are solved through use of Portland cement, a material engineered from limestone, sand, clays, and gypsum. This chemically-constrained mixture often requires sourcing and transportation of materials from afar. Before Portland cement use became dominant after 1910, “natural” cements quarried from the Rosendale and Whiteport Members of the Rondout Formation near Rosendale, New York were extensively used for construction throughout the United States. Although similar clayey and/or sandy dolostones were used across the United States, Rosendale natural cement became the market leader due to its properties and location in the densely populated Northeast.

The historical and modern advantages of using Rosendale cement are that it is single-sourced from one lithologic unit and it requires lower temperatures of calcination (and less energy input) compared to Portland. Growing use for repairs and upkeep of 19th century buildings and infrastructure has resulted in an increased demand for matching materials. Given the rising costs of transport between quarry, cement plant, and usage site, there are financial and environmental incentives for sourcing local equivalents.

~1000 Pennsylvania carbonates with CaCO₃, MgCO₃, and SiO₂ reported were assessed for similarities to the reported bulk chemical composition of the Rosendale and Whiteport members of the Rondout Formation in the Rosendale, New York area (45-51% CaCO₃, 17-26% MgCO₃, 15-23% SiO₂). From this, the most suitable natural cement candidate within Pennsylvania may be the Buffalo Springs Formation. Other possible formations include Ledger, Bellefonte (with and without Axemann), and undifferentiated Beekmantown. Selected portions of the “Coburn-Loysburg” (seven formations extracted together), Keyser and Tonoloway, Nittany, and Gatesburg Formations may be suitable, but finer-resolution geochemical analyses of subunits will be necessary. Many of these units are slightly deficient in SiO₂, and this could be remedied through identifying and quarrying more silica-rich adjacent units. An ongoing sampling and geochemical survey in these target and stratigraphically adjacent units will be used to assess suitability laterally across Pennsylvania.