Britannica
Sources used in this answer
How do slag cements differ in composition from portland cement?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Cement
The cement-making process, from crushing and grinding of raw materials, through roasting of the ground and mixed ingredients, to final cooling and storing of the finished product.
Slag cements differ from portland cement primarily in their chemical makeup and the inclusion of granulated blast-furnace slag, a byproduct of iron production.12
While portland cement is composed essentially of compounds of lime (calcium oxide), silica, and alumina, slag cements are produced by intergrinding or mixing portland cement clinker with varying proportions of granulated slag.312
Key compositional differences include:
- Chemical Balance: Slag cements generally have a lower lime content and a higher concentration of silica and alumina compared to standard portland cement.2
- Proportions: Depending on the specific type—such as Eisenportlandzement or Hochofenzement—the slag content can range from 40 percent to as high as 85 percent.2
- Performance: Due to these compositional adjustments, slag cements often provide increased resistance to chemical attack compared to pure portland cement.2
Additionally, some variations, such as supersulfated cement, incorporate significant amounts of gypsum or anhydrite alongside the slag and a small portion of portland cement to achieve specific setting and strength properties.2