Zeolite for Increasing the Compressive Strength of Adobe in the Historical Site of Belqis

“Belqis” is a historical and archeological site located in Khourasan province in northeast of Iran close to the city of Esfarayen. This study was conducted to consider the composition of the soil used to make the adobe in these structures, which has been exposed to deterioration processes followed by accelerate erosion. In response to this problem, Zeolite was used as an additive to improve soil quality. The finegrained soil texture is full of sand and silt with small amounts of clay. Zeolites has been used in the study in the form of granules (maximum 5 mm). X‐ray diffraction (XRD) and X‐ray fluorescence (XRF) used to define chemical composition and crystalline phase. Scanning electron microscope (SEM) was used for Determination surface characteristics and morphology. The presence of sand in the soil of the region and its decrease in adhesion is the reason for the decrease the compressive strength of clay. The results showed that the amount of 6% zeolite is most effective in improving the compressive strength of adobe. This amount of zeolite increases the compressive strength of clay compared to the samples without zeolite.