An ability of aluminum-bearing substances-amorphous aluminum hydroxide, aluminum sulphate and basic aluminum sulphate to mitigate alkali-silica reactions in Portland cement mortars has been studied. At equivalent dosages in terms of Al₂O₃, these substances are ranged in the following order in respect of inhibiting effect: Al(OH)_1.78(SO₄)_0.61 ≥ Al₂(SO₄)₃ > Al(OH)₃. It is found that the plasticizing agents of the main types used in cement compositions have no influence on the inhibiting effect of aluminum-bearing admixtures. To control the setting time of cement paste, iron(II) sulphate may be used for partial substitution of Al₂SO₄·18H₂O, and this operation is not influence on the results of ASR expansion test.