Natural volcanic ash autoclaved aerated concrete block and preparation method thereof

The invention relates to a natural volcanic ash autoclaved aerated concrete block. The block consists of natural volcanic ash accounting for 50 to 60 percent of total weight, cement accounting for 4 to 6 percent of total weight, quick lime accounting for 15 to 20 percent of total weight, building gypsum accounting for 0 to 2.0 percent of total weight, aluminum powder paste accounting for 0.03 to 0.04 percent of total weight and water accounting for 20to 25 percent of total weight. Meanwhile, the invention also discloses a method for preparing the block. The block has good strength, low density, low thermal conductivity coefficient, low shrinkage and other performances. The method can fully utilize local resources in regions which are abundant in natural volcanic ash but short of sand and fly ash so as to solve the need of local building insulation markets.