This treatment consists in washing the surface of the concrete with diluted acid, then with an alkaline solution. The diluted acid is applied first, to remove the cement and expose the sand and stone; the alkaline solution is then applied to remove all of the free acid; and finally the surface is washed with clear water. The treatment may be applied at any time after the forms are removed. It is simple and effective. Limestone cannot be used in the concrete for any surfaces that are to have this treatment, as the limestone would be affected by the acid. This process has been used very successfully. It is said to be patented.

Aggregate 3/16 Inch white Pebbles

Aggregate 3/16-Inch white Pebbles.

Aggregate 3/8 Inch Screened Stone.

Aggregate 3/8-Inch Screened Stone.

Fig. 119. Quimby's Finish on Concrete Surfaces. Reproduced at actual size.