Concrete normally is defined by the compressive strength it achieves after curing for 28 days.  We intentionally designed the SMarT Foundation for co with a 28-day strength of 2500 psi (pounds per square inch) because this relatively simple mix does not require special inspections.  However, most installers prefer not to wait 28 days to complete a Skystream installation. In those cases, a special mix of high-early-strength (HES) concrete may be used.  High early strength is achieved either with concrete additives or by using special types or greater proportions of Portland cement. The table shows the number of days required to achieve the 2500 psi strength specified for the SMarT Foundation.

There usually is a premium to be paid for HES concrete. However, the “standard” strength of ready-mix concrete from many suppliers is typically 3000 psi to 3500 psi. If this is your situation, the cure time may be much less than 28 days and towers may be installed sooner at no additional cost.  AnemErgonics recommends that you discuss this with your contractor and / or concrete supplier when evaluating foundation cost and installation schedule.  We also suggest that you require the concrete supplier to provide documentation of the mix strength.