Improvement of insulation property of Kahgel plaster with Kaolin and Bentonite micronized

Kahgel is one of the oldest traditional mortars in Iran, which it’s capabilities and performance in throughout history to conserve earthen buildings, show that it can be used as a covering for conservation of earthen architectural structures, but low durability and the need for renewal the plaster due to erosion of rainfall suggest that Kahgel plaster is weak and unstable. It is very essential in finding appropriate scientific methods to enhance the durability and lifespan of Kahgel plaster. The effect of micronized Kaolin and Bentonite additives used to build the different samples of Kahgel plaster on physical and mechanical properties to enhance the durability of Kahgel plaster, showed that micronized Kaolin, reduced saturated hydraulic conductivity of the Kahgel plaster at 82 % level and micronized Bentonite, is decreased by 121 %. In addition micronized Kaolin and Bentonite, increased uniaxial compression strength of the Kahgel plaster at 39 % and 33 %, respectively. Evaluation of water erosion of the samples during rainfall by rainfall simulator showed that use ofKaolin 3% (by weight of Khahgel), the minimum sample’s total dry material loss of the Kahgel plaster reduced to 16/7% and the maximum decrease to 31/4% and increase durability of the Kahgel plaster against water erosion. Experimental results indicated that with decreasing the dimensions of the additive particles, its influence is improved due to the increased surface area of materials.