Page 287 - Masonry and Concrete

Paving

286 CHAPTER EIGHT

Excavation, formwork, reinforcement,
pouring, finishing, and curing vary only in
size and shape. Broomed finishes provide
an economical nonslip surface for con-
crete flatwork, but exposed aggregates,
decorative patterns pressed or stamped
into the surface, or coloring pigments can
change the appearance of concrete paving
from mundane to elegant. Minimum rec-
FOOTING
BELOW ommended concrete strength for exterior
FROST LINE residential paving depends on weather
exposure
FIGURE 8-7
■ 2,500 psi in mild climates with no
Footing for steps.
freeze-thaw exposure
■ 3,000 psi in moderate climates with
only a few freeze-thaw cycles per year
3'-0" MIN.
LANDING and where deicer chemicals are not
typically used

■ 3,500 psi in severe climates with many
freeze-thaw cycles per year and where
deicer chemicals are used routinely.
FIGURE 8-8
In cold climates, air-entrained portland
Split steps.
cement or air-entraining admixtures are
required to provide extra freeze-thaw
durability. Welded wire reinforcing mesh is typical in exterior con-
1
crete paving and should be located 3 up from the bottom of the con-
crete for maximum strength. Control joints, construction joints, and
isolation joints should be located as recommended in Chapter 3 to
minimize shrinkage cracking. Exterior concrete paving should be slip-
resistant when it’s wet to avoid accidents. The most common surface
treatments on exterior flatwork are the float finish and the broom fin-
ish. A float finish provides moderate slip resistance for flat and
slightly sloped surfaces. A broom-finish is safer for surfaces with
greater slope, and for maximum safety, the surface can be tooled with
a series of parallel grooves running perpendicular to the direction of
traffic. Decorative finishes can also be used if the additional cost is

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.