Polymer modifier for concrete, preparation method thereof, and impermeable and waterproof concrete

The invention discloses a polymer modifier for concrete. The polymer modifier for concrete comprises a polymer emulsion and an interface modifier, and the interface modifier comprises silica sol and asilane coupling agent; and the addition amount of the polymer emulsion to the interface modifier is 1:(0.2-1). A preparation method of the polymer modifier comprises the following steps: weighing thepolymer emulsion, the silica sol and the silane coupling agent according to the weight ratio; mixing the silica sol, the silane coupling agent and the polymer emulsion, and performing ultrasonic treatment to obtain a mixed solution. An impermeable and waterproof concrete comprises 230-360 parts of cement, 60-100 parts of fly ash, 28-50 parts of an expanding agent, 650-820 parts of fine aggregate,950-1100 parts of coarse aggregate, 4.35-5.85 parts of a water reducing agent, 100-150 parts of water, 0.85-1.35 parts of an antifoaming agent and 40-80 parts of the polymer modifier. The interface modifier can enhance the dis