huangyhg

grout curing time
how long does it take for grout to cure when it is used to fill cmu?
usually usable for construction loads in 1 to 2 days if not the next day. the 28 story excalibur in las vegas was built on about a 1 floor per week rate.
the purpose of the grout is not for compressive strength of the wall. it is to bond the reinforcement and make the wall serve as a structural element fot lateral/seismic loads. unfortunately, most grout is too strong, so the building does not always act as designed.
the outer fibers of the wall are the concrete masonry units that see the higher stresses. they are essentially fully cured (not like concrete) and control the strength of the masonry. the mortar has a minor effect on the strength of the masonry.
true, unless the question is related to when it is okay to backfill a basement wall.
don phillips
the question is not related to backfilling a basement wall. it has to do with a cmu beam and how long it should be shored for before 100% of the strength is gained (fully cured).
when the grout sample cubes are broken at the specified f'c, then the full strength is available. (make extra cubes and request breaks at 3, 7, 10 days etc.)
keep in mind that the cmus are already cured. the mortar will be cured more than the grout. the grout tests will approximate the curing and ability to transfer the loads from the steel to the masonry units. - are you testing lab cured samples or did you try to approximate the site conditions?
if you have properly prepared grout samples (and not cylinders), you should find very high early strengths in 3 to 7 days. all you need is the aci minimum of the f'm of the hollow prisms (whichever is greater).
once your grout has cured enough to trandfer the load from the steel to the wall construction, you should have enough masonry strength (f'm).

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