The formula for (Roman) concrete was lost for centuries or the Romans didn't share it which also makes sense if you're a militaristic society why give away the

The formula for (Roman) concrete was lost for centuries or the Romans didn't share it which also makes sense if you're a militaristic society why give away the secret to concrete? And it's only recently the secret of Roman concrete was discovered. Also I don't think Roman concrete is exactly the same as what we think of concrete it's not like the Romans poured it out into forms as is done today.