Dastgir
108 posts
TimePosted 02/07/2009 06:16:12
Dastgir says

Hydration and Curing

Dear All,

I want to know when does complete hydration of cement takes place?

Is it completes within moments of pouring of water or takes complete curing period for its completion?

If the first case is true then only hardening takes place during curing?

If the second case is true then  there will be no hydration of interiormost particles since such parts of the cube mould appears dry on crushing even after 28 days curing period?

 

Kind Regards,

Gulam Dastgir

 

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Michael Clark
312 posts
TimePosted 02/07/2009 09:29:44

Re: Hydration and Curing

Hydration of cement continues for many months and years after it is mixed with water. That is why concrete continues to increase in strength for years and why we measure strength at 1, 3, 7, 28 days, etc.

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ovancantfort
57 posts
TimePosted 03/07/2009 06:49:35

Re: Hydration and Curing

I would concur with Dr. Clark. Studies have shown that on samples conserved in good conditions (both laboratory and real-life like bridges supports), slow increase in strength can still be measured more than twenty years after concrete production.

Of course, one could argue that after such a long time, hydration is mostly complete and what we observe is a slow reorganization of the hydrated matrix.

Concerning your initial question, the fact that the concrete looks dry does not mean that hydration, that is chemical reaction with water, is not taking place. Any porous material can hold a certain amount of water (even not chemically bonded) and still look dry.

Best regards,

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Dastgir
108 posts
TimePosted 04/07/2009 15:59:32
Dastgir says

Re: Hydration and Curing

Dear All,

Exactly the same answer i was hoping. But there is one more 

query here. We add water in cement after determining its W/C ratio

by vicat appratus. This ratio gives amount of total water required for 

forming a paste of cement of required consistency. Is this required consistency means the amount of water required for hydration after leaving water loss during paste formation?

If this is so then why curing is needed, when we have already mixed water reqiured for the hydration?

 

Regards,

Gulam Dastgir

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