Roman concrete
The facing of the piers and the foundation consists of cut sandstone blocks bonded by mortar and joined by iron clamps; the interior was filled with Roman concrete, a building technique also observed in the Pa-i-pol bridge. On the upstream face, the river-bed was paved with large stone slabs, probably to prevent the current from undermining the dam base. One former Persian name of the dam, "Shadirwan", derives from this paving.