2 bases and subbases for concrete pavements. 0 10 20 30 40 romans (200 ad) telford (early 1800s) macadam (early 1800s) basesubbase thickness (in) early 1900s. typical basesubbase thickness (early european designs) figure 2. graph. base and subbase thickness for early roads. portland cement concrete (pcc) was originally used as a base and was.