TM
5-818-6/AFM
88-32
where
is the 15 percent finer grain size of the medium to be grouted
D
15
and
D 85 is the 85 percent finer grain size of the grout
N generally should be greater than 25 but in some cases may be as low
as 15, depending upon physical properties of the grout materials. Figure 2
gives a graphic interpretation of this equation. It shows (a) typical grain-
size curves for portland cement, Boston blue clay, ordinary asphalt emul-
sion, and special Shellperm asphalt emulsion, and (b) the lower limits (D 1 5 )
of sand groutable by the above-described grout materials.
6.
P O R T L A N D - C E M E N T G R O U T . Portland- cement grout is a mixture of
portland cement, water, and, frequently, chemical and mineral additives.
The properties of materials generally used in portland-cement grout are
d e s c r i b e d below.
a. Portland Cements. Five types of portland cement, produced to con-
f o r m to the specifications of ASTM Designation C 150 (see ref 15), are used
in cement grouts.
(1) Type I is a general-purpose cement suitable for most cement grout
jobs. It is used where the special properties of the other four types are not
needed to meet job requirements.
(2) Type II cement has improved resistance to sulfate attack, and its
heat of hydration is less and develops at a slower rate than that of type I. It
is often used interchangeably with type I cement in grouting and is suggested
for use where precautions against moderate concentration of sulfate in
groundwaters are important.
(3) Type III cement is used where early strength gains are required in
grout within a period of 10 days or less. It may also be used in lieu of
type I or type II in injection work because of its finer grind, which improves
its injectability.
(4) Type IV cement generates less heat than type II cement and develops
strength at a very slow rate. It is rarely used in grouting.
(5) Type V cement has a high resistance to sulfates. It is not often used
in grouts, but its use is desirable if either the soil to be grouted or the
groundwater at the jobsite has a high sulfate content.
b.
Mixing
Water.
Generally, water suitable for drinking may be
8
Previous Page
