Voids in Hydrated Cement Paste-HCP

The voids in hydrated cement paste are:

Voids in hydrated cement paste
Fig no:1 Structure of hydrated cement paste

Voids in Hydrated cement paste

1.Interlayer space in C-S-H

  • About 18 Å ( 5 to 25 Å) and determined that it accounts for 28 percent porosity in solid C-S-H
  • This void size is too small to have an adverse effect on the strength and permeability of the hydrated cement paste
  • Water in these small voids can be held by hydrogen bonding, and its removal under certain conditions may contribute to drying shrinkage and creep

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2.Capillary voids

  • Capillary voids represent the space not filled by the solid components of the hydrated cement paste. The total volume of a typical cement-water
  • Space not taken up by mixture remains essentially unchanged during the hydration process
  • The cement or the hydration products consists of capillary voids, the volume and size of the capillary voids being determined by the original distance between the anhydrous cement particles in the freshly mixed cement paste (i.e., water-cement ratio), and the degree of cement hydration
  • Well-hydrated, low water-cement ratio pastes, the capillary voids may range from 10 to 50 nm; in high water-cement ratio pastes, at early ages of hydration, the capillary voids may be as large as 3 to 5 μm
  • Larger than 50 nm, referred to as macropores modern literature, are probably more influential in determining the strength and impermeability characteristics, whereas voids smaller than 50 nm, referred to as micropores play an important part in drying shrinkage and creep.

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3.Air Voids

  • Generally spherical in shape
  • Entrapped air voids may be as large as 3 mm; entrained air voids usually range from 50 to 200 μm.air voids in the hydrated cement paste are much bigger than the capillary voids and are capable of adversely affecting the strength

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MartinPrere

Hellow my name is MartinPrere. Wery capable article! Thx 🙂