mit handling the object if reasonable care is used. Ridges formed by joints in forms are carefully chipped off, the concrete surface is thoroughly wet down and rubbed with a carborundum block, being kept wet constantly. The earlier the surface is rubbed after form removal, the easier will it be to remove any surface irregularities due to form inequalities. In other words, the concrete should be rather green. The rubbing removes the inequalities
crushed feldspar, mica and mica spar, crushed slag, white sand and white cement in various combinations permit an endless variety of tone. Such concrete mixtures are prepared and placed in the usual way. When the concrete has hardened so that forms may safely be removed the surface of the concrete is gone over in one of several ways to expose the aggregates. When selected aggregates are used the surface finish is obtained by washing off
Delicate tracery such as ordinarily would be left to the stone cutter’s art is readily molded in concrete. The more intricate patterns are reproduced by casting the material in glue molds. The units are afterward assem
bled just as is any other masonry.
and fills the pores and small cavities, giving the surface a uniform appearance. Such a treatment is proof against the pitting and scaling that frequently results from painting on a cement and water paint, which is not to be advocated as a surface finish.
By far the most attractive surface finishes that can be given to concrete are those which are in large part arranged when preparing the concrete mixtures. Selected aggregates used instead of sand will control, almost as desired, the color of the finished surface. Marble chips, granite screenings,
the film of cement that coats the particles, thus exposing their surfaces in the surface of the concrete and in that way revealing their color. If the forms are removed within twenty-four hours after placing the concrete in the mold it is usually possible to wash off the surface film of cement by merely scrubbing the surface of the object with a stiff bristle brush kept wet with water. If, however, the concrete has become too hard to permit exposing aggregate surfaces in this manner an acid wash is used. Generally a solution consisting of i part of commercial muriatic acid in 3 or 4 parts of water is applied
crushed feldspar, mica and mica spar, crushed slag, white sand and white cement in various combinations permit an endless variety of tone. Such concrete mixtures are prepared and placed in the usual way. When the concrete has hardened so that forms may safely be removed the surface of the concrete is gone over in one of several ways to expose the aggregates. When selected aggregates are used the surface finish is obtained by washing off
Delicate tracery such as ordinarily would be left to the stone cutter’s art is readily molded in concrete. The more intricate patterns are reproduced by casting the material in glue molds. The units are afterward assem
bled just as is any other masonry.
and fills the pores and small cavities, giving the surface a uniform appearance. Such a treatment is proof against the pitting and scaling that frequently results from painting on a cement and water paint, which is not to be advocated as a surface finish.
By far the most attractive surface finishes that can be given to concrete are those which are in large part arranged when preparing the concrete mixtures. Selected aggregates used instead of sand will control, almost as desired, the color of the finished surface. Marble chips, granite screenings,
the film of cement that coats the particles, thus exposing their surfaces in the surface of the concrete and in that way revealing their color. If the forms are removed within twenty-four hours after placing the concrete in the mold it is usually possible to wash off the surface film of cement by merely scrubbing the surface of the object with a stiff bristle brush kept wet with water. If, however, the concrete has become too hard to permit exposing aggregate surfaces in this manner an acid wash is used. Generally a solution consisting of i part of commercial muriatic acid in 3 or 4 parts of water is applied