UFC 3-270-04
15 March 2001
Table 13.1. Aggregate Desirability
Group
Rating
Description
Typical Aggregates
I
Most desirable
Calcareous
Limestone, Dolomite
II
Intermediate
Nonquartzose silicates
Basalt, Dolorite Gabbro,
Andesite, Diabase
(traprock)
III
Aggregates that spall
High silica content
Granites, High Silica
and crack at high
quartzose
Content Igneous Rocks,
temperature
Quarts Bearing Schists
and Gneisses
IV
Least desirable
Silica not combined to
Quartzite, Quartz,
form silicates
Chert, Flint
13.3. Aggregate Performances. Lightweight aggregates such as expanded shale tend to
perform better than conventional natural concrete aggregates when exposed to high
temperatures. Good results have also been reported for air-cooled slag aggregates. Hydrated
portland cement that has lower calcium hydroxide content appears to be preferable to those with
higher contents for high-temerature applications. Therefore, some benefit may be obtained by
using portland cement blended with slag cement. For temperatures of 1,500 degrees Fahrenheit
(816 degrees Celsius) or more, high alumina cement will provide superior performance over
conventional portland cement. Repair of concrete that has suffered thermal damage is a difficult
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