Airtight concrete and preparation method thereof

The invention relates to the technical field of concrete materials, and particularly discloses airtight concrete and a preparation method thereof.The airtight concrete is prepared from, by weight, 800-900 parts of machine-made sand, 950-1050 parts of gravel, 275-320 parts of cement, 65-100 parts of fly ash, 6-10 parts of an additive, 25-30 parts of an airtight agent and 150-160 parts of water, and the ratio of coarse aggregate to fine aggregate of the gravel is 3-4; the preparation method comprises the following steps: uniformly pre-mixing the gravel, the machine-made sand and 50% of cement to obtain a premix I; uniformly pre-mixing the fly ash, the airtight agent, the water reducing agent, the remaining 50% of the cement and the water to obtain a premix II; and adding the premix II into the premix I, and uniformly stirring to obtain the airtight concrete. The airtight concrete can be used for tunnel construction and has the advantage of gas permeation resistance. 本发明涉及混凝土材料技术领域，具体公开了一种气密性混凝土及其制备方法，气密性混凝土包括由以