Re: Hydration and Curing

The w/c ratio is a mechanical property that depends mainly on the fineness and granulometric distribution. It is not related to the stoechiometric water needed.

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Re: Hydration and Curing

Dear Dastgir

During mechanical testing of cement we are determining water for W/C and for normal consistency. For only hydration portland cement requires about 18% water of its mass. But for normal consistency we're usually adding 24-28% water. Part of excess water evaporates and other parts remains in structure of concrete, pores etc.

Regarding to period of hydration of cement I want to add, that curing  of cement takes place long, but we can't see that without special devices. Bellow I bring the table, that show the level of hydration (thickness of hydrated layer in microns) of main clinker minerals.

  Depth of hydration of clinker minerals, mk (By Butt, Sychev, Okorokov, Timashev)

  Minerals   3d.      7d.     28d.   3m.    6m. 

   C3S        3.5      4.7     7.9     14.5    15

   C2S        0.6      0.9     1.0      2.6     2.7

   C3A       10.4    10.7    11.2    13.5    14.5

  C4AF       7.7      8.0      8.4    12.2    13.2

Of caurse you know the avarage sizes of clinker minerals. As you can see there are grains' layers that have to be hydrated (especially C2S). So the table data is additional information for you.

Best regards. Davit Babayan. 

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Re: Hydration and Curing

Dear Davo,

Is there any mathematical relationship between Time V/S strength?

When we plot graph for 1 to 28 days strength, logarithmic relatiosheep seems

best fit, but it shows increase in strength continuously.

Regards,

Gulam Dastgir

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