Howe much postage to send a postcard from US to Canada? As of September 2014, it costs $1.15 to ship a post card  internationally. If it exceeds 4 3/4 inches high or 9 1/4 inches  long, you will be charged the First Class Mail In â¦ ternational price. + 3 others found this useful.
Concrete is never truly done curing, but the minimum wait time should be 28 days. A slab typically cures at least 80% during that time. I suspect the manufacturer is asking you to proceed cautiously to avoid a lawsuit. If you (or your client) can wait that long, then wait the 120 (or more) days. But I wouldn't put any flooring on it inside a month.
More Wear-Resistant Concrete: Well-cured concrete (28 day curing period) will develop a surface twice as wear resistant as a surface that is cured for only three days. Proper curing prevents dusting and means less cracking, crazing, and spalling of the concrete.ecommended practice calls for a minimum of seven days curing or the time necessary to attain 70% of the specified compressive or flexural strength, whichever period is less. (Refer to ACI - 308, Standard Practice for Curing Concrete.).