2523 - Portland cement, aluminous cement, slag cement, supersulfate cement and similar hydraulic cements, whether or not colored or in the form of clinkers:

This HTS category, 2523, encompasses various types of hydraulic cements essential for construction and manufacturing. It specifically includes Portland cement, known for its widespread use in concrete, as well as aluminous cement (also known as high-alumina cement), which offers rapid hardening and resistance to chemical attack. Additionally, slag cement, created from industrial byproducts, and supersulfate cement, a specialized blend, fall under this classification. The category also covers similar hydraulic cements, whether they are naturally colored or presented in their clinker form, which are intermediate products requiring further processing into finished cement.

Distinguishing this category from its sibling entries at the Section V, Chapter 25 level, it is crucial to note that 2523 focuses exclusively on cements. While other categories in Chapter 25 might deal with raw mineral materials like stone (Chapter 25), plastering materials, lime, or sulfur, this heading specifically addresses the manufactured binder agents that chemically harden when mixed with water. It moves beyond the raw inputs to the foundational component of many building materials.

Within HTS 2523, the subsequent subdivisions refine the classification of these hydraulic cements. Cement clinkers, the granular material produced during the cement manufacturing process that serves as the primary ingredient for finished cement, are specifically identified under 2523.10.00.00. Further distinctions are made for aluminous cement (2523.30.00.00) and other hydraulic cements (2523.90.00.00) not otherwise specified, allowing for precise tariff application based on the specific type and composition of the hydraulic cement product.