Structure of Hydrated Cement:

The product of hydration of cement, most generally known as C-S-H gel, is in the form of thin fibrous crystals of infinitely small size. The C-S-H gel has little more than two times the volume of the original unhydrated cement volume. The

C-S-H gel plays an important role in governing the various properties of concrete both in plastic as well as in hardened stage, such as strength, permeability, durability, drying shrinkage, elastic properties, creep, volume stability, etc. The hydrated cement paste is considered to consist of hydrates of various compounds, unhydrated cement particles and water. Water within the hydrated cement paste partly remains inside the gel pores and partly in the capillary cavities.