a. Rock Cube Soundness. The sodium or magnesium sulfate soundness
test for all rock Types (1, 2, or 3) shall be performed on a test sample of
5000 ± 300 grams of rock fragments, reasonably uniform is size and cubical
in shape and weighing, after sampling, approximately 100 grams each. They
shall be obtained from rock samples that are representative of the total
rock mass, as noted in ASTM D 4992, and that have been sawed into slabs as
described in ASTM D 5121. The samples shall further be reduced in size by
sawing the slabs into cubical blocks. The thickness of the slabs and the
size of the sawed fragments shall be determined by the size of the available
test apparatus and as necessary to provide, after sawing, the approximate
100 gram samples.
Due to internal defects, some of the cubes may break during the sawing
process or during the initial soaking period. Do not test any of the cubes
that break during this preparatory process. Such breakage, including an
approximation of the percentage of cubes that break, shall be noted in the
test report.
After the sample has been dried, following completion of the final test
cycle and washed to remove the sodium sulfate or magnesium sulfate, the loss
of weight shall be determined by subtracting from the original weight of the
sample the final weight of all fragments which have not broken into three or
more fragments.
The test report shall show the percentage loss of the weight and the
results of the qualitative examination.
b. Rock Slab Soundness. When specified, the rock
shall also be tested in accordance with ASTM D 5240.
(1) For projects located north of the Number 20 Freeze-Thaw Severity
Index Isoline (Map below approximates the map located in ASTM D 5312):
Unless otherwise specified, the average percent weight loss for Rock Type
1 shall not exceed 20 percent when sodium sulfate is used or 25 percent
when magnesium sulfate is used, and for Rock Types 2 and 3, the average
percent weight loss shall not exceed 25 percent for sodium sulfate
soundness or 30 percent for magnesium sulfate soundness.
(2) For projects located south of the Number 20 Freeze-Thaw Severity
Index Isoline, unless otherwise specified, the average percent weight loss
for Rock Type 1 shall not exceed 30 percent when sodium sulfate is used or
38 percent when magnesium sulfate is used, and for Rock Types 2 and 3, the
average percent weight loss shall not exceed 38 percent for sodium sulfate
soundness or 45 percent for magnesium sulfate soundness.
Map of the Conterminous United States Showing the Number 20 Freeze-Thaw
Severity Index Isoline
Adapted from ASTM D 5312
4. FIELD DURABILITY INSPECTION
Rock that fails to meet the material requirements stated above in a, b, or
c (if specified), may be accepted only if similar rock from the same source
has been demonstrated to be sound after five (5) years or more of service
under conditions of weather, wetting and drying, and erosive forces similar to
those anticipated for the rock to be installed under this specification.
A rock source may be rejected if the rock from that source deteriorates in
three (3) to five (5) years under similar use and exposure conditions expected
for the rock to be installed under this specification, even though it meets
the testing requirements stated above.
Deterioration is defined as the loss of more than one-quarter (1/4) of the
original rock volume, or severe cracking that would cause a block to split.
Measurements of deterioration are taken from linear or surface area particle
counts to determine the percentage of deteriorated blocks. Deterioration of
more than 25 percent of the blocks shall be cause for rejection of rock from
the source.
5. GRADING
The rock shall conform to the specified grading limits
after it has been placed within the matrix of the rock riprap.
Specification Date 1/97
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