140_151SubgradeFrmwrk
10/21/04
11:26 PM
Page 145
TYPE V cement is commonly used as type II/type V cement,
which is engineered to resist severe sulfate action where soils
and ground water have high sulfate content. Sulfates can rapidly
deteriorate concrete mixes. As previously stated, most cement
type II are type specified type II/type V.
Admixtures:
Admixtures are often used in concrete when they will affect a
desired change in the properties of freshly mixed concrete. Often
Cement aggregates and sand; note color range of materials.
used admixtures are:
Cement Types (most common types):
1. Synthetic fibers (reinforcing).
TYPE I cement, typically called white cement, and best for
2. Retarders (slows concrete setting).
architectural walls and hardscape.
3. Accelerators (speeds concrete setting).
4. Fly ash, which has many benefits for concrete, e.g. aids in
1. White cement has a much brighter or higher L factor (the
pumpability, finishing, and reduces ASR (Alkali-Silica
amount of measured reflected light) and has less variation
Reaction). May promote cracking and should be avoided in
in color differences between loads.
mix designs unless specifying glass Lithocrete®.
2. White cement gives more intense colors when blended with
integral colors.
3. Contains very little iron or manganese oxides.
4. Due to the fact that it’s a finer grind, white cement hydrates
faster and is less user friendly than other types.
5. White cement is more costly than types II, III, and V.
5. Water reducers.
6. Air entrainment.
7. Color pigments used extensively in architectural concrete,
either via dust-on or integral.
8. Shrinkage reducing admixtures (shrinkage admixtures are
not effective with type III cement).
TYPE II (High Early) is the most commonly used cement.
Shaw & Sons does not recommend dust on colors. Although it
However, due to sulfate problems, this type has been replaced
can contribute to a greater color intensity, its use is usually
by type II/type V for most use.Type II/type V is a courser grind
more inconsistent among installers. The finished surface can
and contains iron and manganese oxides that produce a gray
chip, showing gray matrix, and can result in thin areas that wear
colored product. Benefits are: lower cost than types III and
through prematurely.
type I white; develops strength slower, which reduces rapid
hydration that produces less cracking; and it is more user friendly.
Concrete Material Sourcing:
It is crucial that the concrete being supplied to a project for a
TYPE III is more finely ground. This cement:
given paving type be consistent in material source (cement and
1. Is lighter in color than type II.
aggregates) throughout the duration of the project. There are sever-
2. Develops design strength typically in less than a week.
al reasons why adjacent concrete pours differ in appearance:
3. Has a higher rate of hydration and therefore generally greater
s hrinkage can be expected.
4. Costs between type I white and type II.
5. Color between type I and II and is therefore a good range for
architectural concrete.
1. Change in cement type.
2. Change in fine aggregate (washed concrete sand) type. Sand
is approx. 52% of the volume and is also 52% of what you
visually see with acid etch, sandblast and exposed aggregate
finishes.
TYPE IV is a low-heat cement. This type cement is no longer
3. Change in coarse aggregate type.
manufactured because mineral admixtures offer a less expensive
4. Change in mix design characteristics including slump,
way to achieve low-heat quality.
water/cement ratio or admixtures.
145