Figure 17-4.—Retaining wall.
to be poured, adding a waste factor, and multiplying this
volume times the amount of each component in the
1-cubic-yard mix design. The manner of doing this is
described in the following example.
Example Problem: Using the mix design deter-
mined previously in this chapter, determine the total
amount of materials needed to construct the
75-foot-long retaining wall shown in figure 17-4. The
1-cubic-yard mix design is recapped below.
Cement:
6.49 sacks (Type IA)
Water
36.6 gallons
Coarse aggregate:
1,735.0 pounds
Fine aggregate:
1,153.0 pounds
Air content:
5.0 percent
To determine the total quantity of each of the above
ingredients needed for the retaining wall, you must first
calculate the total volume of concrete required. As you
should know by now, an easy way to do this is to break
the retaining wall into simple geometric shapes and then
determine and accumulate the volumes of those shapes.
Since you should know how to do this, we will simply
say that the total volume of the retaining wall is 63.7
cubic yards. To this figure you add a 10-percent waste
17-10
factor so that the adjusted amount of concrete needed
for the project is 70.07 cubic yards. (Had the initial
volume needed been greater than 200 cubic yards, you
would have used a 5-percent waste factor.)
Now that you know the total amount of
concrete needed, you can determine the total
quantity of each of the concrete ingredients by
simply multiplying the amount of each ingredient
needed for 1 cubic yard by the total amount of
concrete required for the retaining wall. As an
example, you need 1,153 x 70.07 = 80,790.7 pounds,
or 40.4 tons, of fine aggregate for the retaining wall.
The other ingredients are computed in the same way.
That being done, you find that the following
quantities of ingredients are need for the project:
Cement:
455.0 sacks (Type IA)
Water:
2,567.0 gallons
Coarse aggregate:
60.8 tons
Fine aggregate:
40.4 tons
BITUMINOUS MIX DESIGN
Hot-mix bituminous concrete for pavements is a
mixture of blended aggregate filled with bituminous
cement binder. The materials are heated while being
mixed to promote fluidity of the bitumen for thorough
coverage of the aggregate particles. The design of a
bituminous concrete mix consists of the determination
of an economical blend and gradation of aggregates
together with the necessary content of bituminous
cement to produce a mixture that will be durable, have
the stability to withstand traffic loads, and be workable
for placement and compaction with the construction
equipment available.
The procedures described in this section are
performed during the design of a hot-mix bituminous
concrete. They include testing, plotting the results on
graphs, and checking the readings against values from
the design tables. Testing of the ingredients and the mix
is started before and continued throughout the paving
operations. Specific test procedures are not covered in
this discussion; instead, you should refer to chapter 13
of this TRAMAN and to Materials Testing,
NAVFAC MO-330.
