This is a great question. I think there are three aspects to consider for every concrete pour, depending on the application. The first of these is the PSI, or the compressive strength rating of the concrete. In the Atlanta-metro area of Georgia, our seismic zone and local ordinances 3000PSI for most exterior and structural concrete pours. At BOSS Concrete we go a step further and use 4000PSI on almost everything we do. Higher Concrete PSI means stronger compressive strength and more resistance to surface abrasion.