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Technical Cement Forum / Cement Autocalve test Fail

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Naresh 13/05/2016 11:38:54

Cement Autocalve test Fail

Dear Sir,

What may be the reason of failing Autoclave test in OPC 53, please note that we are maintaining Free Lime 1.60 -1.70 and MgO content in clinker is 1.50 % and Le-Chatlier expansion is 1 - 2 MM.

Also note that % C3A is around 5 - 6.

Now, We want to know that what is the reason that autoclave test is fail in this situation.

Regards,

Naresh Gohil

el quimico 22/06/2016 14:34:06

1-2 mm is by any means no fail. Standard reqs are <10 mm, I see no worries here. Cross check with other new le chatelie.
Could happen that if the KF uniformity is not good, one could get bigger particles of clinker free lime in clusters next to belite, although the total free lime shows normal.

Regards

chari 29/06/2016 11:13:14

As told by Ted a year back "failure of cement to pass the autoclave test was not due to only free lime or free magnesia, but to the amount of coarse (>74um) particles in the cement. Unsoundness is caused by a increase in volume (due to hydration products) which occurs after the cement paste has set. The larger particles in coarse cement continue to hydrate well after the rest of the paste has set around them. Therefore any subsequent volume increases cannot be absorbed by the plasticity of the paste, and expansive cracking may occur."

chari

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