High strength high temperature resistance semi-lightweight high alumina castable and its preparation method

The invention discloses a high strength high temperature resistance semi-lightweight high alumina castable and its preparation method. The castable is prepared by mixing 60 wt% of a grading high alumina hollow ceramsite main material, 40 wt% of an auxiliary material and 0.55 wt% of an additive, wherein the main material is made from the matrix of high alumina hollow ceramsite with the particle size being 5-10mm and high alumina hollow ceramsite with the particle size being 1-5mm; the auxiliary material is composed of an expanding agent, a filler, a hard clay powder, binding clay, a volume density modifying agent and a calcium aluminate cement; and the additive is composed of a water-reducing dispersant and an anti-knock agent. The castable prepared in the invention has advantages of high strength, high temperature resistance and semi-lightweight. Detected after sintering for 3 hours at the temperature of 1350 DEG C, the average value of volume density is 1.77g/cm , the average value of flexural strength is 11.4MPa, and the average value of compressive strength is 85.3MPa. Chemical components contain 35.60% of SiO2 and 48.50% of Al2O3.