Specification - Concrete Mix Design, Quality Control and Specification - page 115

Table 6.2 Test methods for alkali-silica reactivity
Test name Purpose Type of test Duration of test Comments

ASTM C 227, Potential
alkali-reactivity of
cement-aggregate
combinations
(mortar-bar method)

To test the susceptibility
of cement-aggregate
combinations to
expansive reactions
involving alkalies

Mortar bars stored
over water at
37.8°C (100°F) and
high relative
humidity

Varies: irst
measurement at
14 days, then 1, 2,
3, 4, 6, 9, and 12
months; every 6
months after that
as necessary

Test may not produce signiicant
expansion, especially for carbonate
aggregate. Long test duration.
Expansions may not be from alkali-
aggregate reaction (AAR).

ASTM C 289, Potential
alkali-silica reactivity
of aggregates

To determine potential
reactivity of siliceous
aggregates

Sample reacted with
alkaline solution at
80°C (176°F).

24 hours Quick results. Some aggregates give low

expansions even though they have high
silica content. Not reliable.

ASTM C 294,
Constituents of
natural mineral
aggregates

To give descriptive
nomenclature for the
more common or
important natural
minerals; an aid in
determining their
performance

Visual identiication Short duration; as

long as it takes to
visually examine
the sample

These descriptions are used to
characterise naturally occurring
minerals that make up common
aggregate sources.

ASTM C 295,
Petrographic
examination of
aggregates for
concrete

To outline petrographic
examination
procedures for
aggregates; an aid in
determining their
performance

Visual and
microscopic
examination of
prepared samples;
sieve analysis,
microscopy, scratch
or acid tests

Short duration;
visual examination
does not involve
long test periods

Usually includes optical microscopy.
Also may include x-ray diffraction
(XRD) analysis, differential thermal
analysis, or infrared spectroscopy (see
ASTM C 294 for descriptive
nomenclature).

( Continued )