The invention discloses multi-phase combined lightweight aggregate concrete and a preparation method thereof. The multi-phase combined lightweight aggregate concrete is prepared from the following raw materials in part by weight: 1 part of
cement, 0.40 to 0.50 part of
fly ash, 1.836 to 2.219 parts of
pumice sand, 0.028 to 0.043 part of corn
straw fibers, 0.006 to 0.008 part of polyphenyl particles, 0.23 to 0.33 parts of rubber particles, 0.010 to 0.015 part of additive, 0.005 to 0.007 part of
foaming agent, and 0.50 to 0.55 parts of water. The preparation method comprises the following steps:1, preparing thin-
coating pumice sand and thin-
coating straw fibers; 2, performing interference treatment of polyphenyl particles and rubber particles; 3, uniformly stirring the
cement,
fly ash, water, additive and thin-
coating pumice sand; and 4, adding the polyphenyl particles, rubber particles and thin-coating
straw fibers in turn, and continuing to stir. When the method is used, the mechanical performance of the lightweight aggregate concrete can be improved effectively, the thermal-insulation and heat-preservation performance is enhanced, and production cost is lowered.