FAILED 7-DAY STRENGTH

hi everyone, What could possibly caused the 7-day strength of mortar to fail and be able to pass in the 3 & 28-day strength requirement?

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re FAILED 7-DAY STRENGTH

Hello Norew,

This sounds like a testing issue. Has this been observed on just one test sample, or is it happening consistently?

Regards,

Ted.

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re FAILED 7-DAY STRENGTH

This has happened already for quite a number of samples.

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re FAILED 7-DAY STRENGTH

Hello Norew,

Is the cement in question GPC or PPC?

By how much is the 7d strength failing?  If it is only failing by a small amount then it may be that there has been a change in the distribution of cement particles somewhere in the range 3-32um, or a change in the amount of C3A in the clinker or the ratio of C2S to C3S.

Or even possibly a change in the alkali sulphate level in the clinker. (the quantity of soluble alkalis affects clinker mineral reactivity and hydration rate)

Regards,
Ted.

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