Sarooj is a traditional water-resistant mortar used in Iranian architecture,[1][2] used in the construction of bridges[3] and yakhchāl, ancient Persian ice houses.
[citation needed] A portion of furnace slags from baths is combined with cattail (Typha) fibers, egg, and straw, and fixed, then beaten with a wooden stick for even mixing.
Mosaddad et al. report the use of a mixture consisting of lime, sand and ash in the construction of an 1800 year-old Sasanian bridge-dam on the Karoon river south of Shooshtar.
[3] The Sheikh's biogas bath-house in Isphahan featured a water-impermeable sarooj composed of lime, egg white, and bamboo dust.
[2] Another alternative formulation used for yakhchāl and water tanks in Iran uses "sand, clay, egg whites, lime, goat hair, and ash in specific proportions.