Mud brick is one of the materials of main structures of Iranian ancient buildings One of these buildings, is the Sam Castle in Kuhe-Khawje in Sistan . The necessity of restoration of this castle, shows the necessity of research about mud bricks. This paper deals with the finding an optimum composition for the mud bricks that used in restoration of the Sam Castle. The studies and the experiments show that the improved bricks (with the optimum composition) in comparison with the normal one; have a better
quality. In addition to economical aspects, using agricultural and animal husbandrial wastages (that available in Sistan) must also be considered from the environmental views.
)