a nitrite salt as essential components the potassium silicate used in the second invention is the same potassium silicate as mentioned above in the description of the first invention the amount incorporated in the snow melting antifreezing agent of the second invention may also be the same as the amount described above as examples of the nitrite salt used in the snow melting antifreezing agent of the second invention sodium nitrite calcium nitrite and the like can be given with a preferable nitrite salt being sodium nitrite although there are no particular limitations to the amount of the nitrite salt in the total amount of the snow melting antifreezing agent of the second invention the amount of 1 to 40 and particularly 3 to 30 is preferable if greater than 40 it is difficult to dissolve the nitrite salt if less than 1 the effect of combined use is reduced the amount of nitrite salt used is preferably in a range of 2 to 4 000 parts by weight and particularly preferably 7 5 to 600 parts by weight for 100 parts by weight the potassium silicate on the solids basis the use of a nitrite salt in combination with potassium silicate in the second invention increases the effect of the potassium silicate to suppress or prevent deterioration of concrete while ensuring the snow melting and antifreezing effect of the potassium silicate as in the case of the first invention the addition of an alkali metal salt excluding a nitrite salt is desirable in order to increase the effect of the snow melting antifreezing agent of the second invention the same.