With new technology available, Isaac Johnson made the first Modern Portland cement. New firing techniques allowed for the management of extremely hot kilns. This allowed clinkering of the minerals in chalk and clay that produce the chemical hardening of cement under water. The raw materials required are calcium, silicon, aluminum, and iron. This manufacturing allows for much stronger cement to be produced. The industrial Revolution also provided gypsum control methods, and ball mills to grind mass amounts of raw materials. There are currently six classifications of Portland cement. The specific types and characteristics of each are listed in the table below.
| Class | Characteristics | Use | |
|---|---|---|---|
| Type I | General Purpose | High C₃S Content / Early Strength Development | General Construction |
| Type II | Mod. Sulfate Resistant | Low C₃A Content | Structures Exposed to Soil and Water |
| Type III | High Early Strength | Elevated C₃S Content / Finely Ground | Rapid & Cold Weather Construction |
| Type IV | Slow Reacting | Low C₃S & C₃A Content | Massive Structures |
| Type V | High Sulfate Resistance | Very Low C₃A Content | Structures Exposed to High Levels of Sulfates |
| White | White Coloring | No C₄AF / Low MgO | Decorative |