Cement Mason Apprentice - Nature of Work
Cement Masons work with
concrete, one of the most common and durable materials used in
construction. Once set, concrete—a mixture of Portland cement, sand,
gravel, and water—becomes the foundation for everything from decorative
patios and floors to huge dams or miles of roadways.
masons place and finish the concrete. They also may color concrete
surfaces; expose aggregate (small stones) in walls and sidewalks; or
fabricate concrete beams, columns, and panels. In preparing a site for
placing concrete, cement masons first set the forms for holding the
concrete and properly align them.
They then direct the
casting of the concrete and supervise laborers who use shovels or
special tools to spread it. Masons then guide a straightedge back and
forth across the top of the forms to “screed,” or level, the freshly
placed concrete. Immediately after leveling the concrete, masons
carefully smooth the concrete surface with a “bull float,” a
long-handled tool about 8 by 48 inches that covers the coarser materials
in the concrete and brings a rich mixture of fine cement paste to the
After the concrete has been leveled and floated, cement
masons press an edger between the forms and the concrete and guide it
along the edge and the surface. This produces slightly rounded edges
and helps prevent chipping or cracking. Cement masons use a special
tool called a “groover” to make joints or grooves at specific intervals
that help control cracking. Next, they trowel the surface by hand
and/or might even use powered trowel machines.
masons perform all the steps of laying concrete, including the
finishing. As the final step, they again trowel the concrete surface
back and forth with hand or powered trowels to create a smooth finish.
For a coarse, nonskid finish, cement masons brush the surface with a
broom or stiff-bristled brush. For a pebble finish, they embed small
gravel chips into the surface. They then wash any excess cement from
the exposed chips with a mild acid solution. For color, they use
colored premixed concrete or color hardener. On concrete surfaces that
will remain exposed after the forms are stripped, such as columns,
ceilings, and wall panels, cement masons cut away high spots and loose
concrete with (powered) hammer and chisel, fill any large indentations
with a Portland cement paste, and smooth the surface with a carborundum
stone. Finally, they coat the exposed area with a rich Portland cement
mixture, using either a special tool or a coarse cloth to rub the
concrete to a uniform finish.
Throughout the entire process, cement
masons must monitor how the wind, heat, or cold affects the curing of
the concrete. They must have a thorough knowledge of concrete
characteristics so that, by using sight and touch, they can determine
what is happening to the concrete and take measures to prevent defects.