concrete curing

[white98ta]

greetings to all...
what is the recommended curing time for a concrete 4" monolithic or slab on grade, 3000psi with fibremesh...BEFORE masonary block is stocked?

 

[Ron]

I would give it at least 7 days, depending on the strength gain of the concrete, the weather conditions, and the unit load on the slab.

 

[jjeng2]

85% of design strength is a rule of thumb I use for removing shoring of walls or building masonry walls on top of slabs. You need to use judgement though. If its just a 8" masonry interior partition you could be a little more lenient, if its a filled solid wall that is load bearing, maybe more stringent.

 

[concreteguru]

Using a percentage of design strength allows for the use of performance based concrete mix designs, which is the better alternative. Performance based mix designs allow suppliers to design mixes that will achieve higher ultimate strengths, lower maintenance costs and extend the life cylcle of the concrete structure/pavement, etc. Curing for 7 days gives you no tangible data that the required strength has been reached. This is especially true now that supplementary cements such as fly ash or ground-granulated blast furnace slag cement are prevalent in the marketplace. These SCM's traditionally hydrate and gain strength slower than Ordinary Portland Cement.

Fred J. Croen, RSM
Engius, LLC
Boston, MA
www: engius.com

 

[JConc]

I would ask the concrete supplier's Tech Services to give you their recommendations. They will have the best estimate of what strength you will achieve under the ambient conditions and your curing practices.

 

[sdz]

7 days if you can keep the block layers off for that long. Perhaps a curing membrane would be a good solution.