CAN WE CURRENTLY PRODUCE ROSENDALE-STYLE NATURAL CEMENT IN PENNSYLVANIA USING AVAILABLE AND SUITABLE SOURCES OF EXTRACTED CARBONATES?

Hydraulic, or water-setting, cement is critical for construction needs. Modern cement needs are predominantly addressed through use of Portland cement, a material engineered from limestone, sand, clays, and gypsum and processed at a central location. Before 1910, locally produced “natural” cements were extensively used for construction. These were produced at or near quarries directly from carbonate rocks with minimal chemical modifications beyond addition of gypsum. Rosendale natural cement was produced from members of the Rondout Formation near Rosendale, New York, was the market leader in American natural cements, and was extensively used due to its properties, marketing, and location in the Northeast.

The advantages of Rosendale cement are that it is locally sourced from one or more adjacent lithologic units, it requires lower temperatures of calcination compared to Portland, and it needs less energy input for transportation of source materials, roasting, and processing. Its growing use for repairs and upkeep of 19th century buildings and early 20th century roads 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.

We have collected samples of quarry products across Pennsylvania to assess whether commonly produced, pavement sub-base materials may be directly suitable for Rosendale-style natural cement. These samples were selected in quarries extracting Cambrian, Ordovician, and Silurian lithologic units that are compositionally similar to both the Rondout Formation in Rosendale, New York and historical samples of produced natural cement. Through portable XRF analyses of these quarry materials, we have determined that none are currently feasible for this purpose, as they are deficient in MgO and/or SiO₂. However, there are lithologies available in Pennsylvania that are potentially suitable, including but not limited to the Buffalo Springs, Ledger, Tonoloway, Snyder, Hatter, Bellefonte, and Gatesburg Formations and combinations of multiple, adjacent units to satisfy CaO, MgO, SiO₂, and Al₂O₃ requirements. Further work is needed to assess the commercial and compositional suitability of these options.