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64
erties is effected by climate and the ability of various geolo- In some cases, the agencies specify varying levels depending
gies to meet the criteria. on traffic or aggregate type. The frequency distribution in
Figure 27 represents the agencies' most stringent require-
ments. The states with multiple levels are shown in Table 15.
3.3.2 LA Abrasion Test
Information on aggregate hardness and its resulting resis- 3.3.3 Sulfate Soundness
tance to degradation during handling and construction is
almost universally measured using AASHTO T96, "Los Ange- Aggregates can deteriorate from wetting and drying or
les Abrasion Test." AASHTO T96 may also be related to the freezing and thawing cycles. The sulfate soundness test
expected polish resistance of the aggregate under traffic. The simulates the effects of the expansion of water in the aggre-
survey indicated that 96% of the responding agencies spec- gate pores during freezing. An aggregate sample is satu-
ify AASHTO T96. California DOT (CalTrans) and Illinois rated with either a magnesium or sodium sulfate solution,
DOT specify their own version of the test. Only two agencies placed in a drying oven, and dried to a constant mass, which
that responded to the survey, Maine and Ontario, do not spec- causes the sulfate to crystallize in the aggregate pores. Upon
ify AASHTO T96. Instead, they specify the micro-deval test. reintroducing the sample into the sulfate solution, the sul-
In addition, Ontario specifies the British Standard for Polish fate crystals expand when they are rehydrated. This expansion
Stone Value and Aggregate Abrasion Value. The aggregate is similar to the expansion of water freezing in the aggregate
abrasion value test was developed by Ontario and produces pores. Of the responding agencies, 73% specify AASHTO
results similar to the LA abrasion test, with more portable T104 for aggregate durability in HMA. Sodium sulfate is
equipment (115). specified by 64% and magnesium sulfate by 30% of the agen-
Figure 27 shows a frequency distribution of the AASHTO cies specifying AASHTO T104. Two agencies (6%) allow
T96 criteria specified by state agencies based on 43 responses. either sodium or magnesium sulfate. Three agencies specify
60
50
Percent of Agencies Specifying
40
30
20
10
0
30 35 40 45 50 55 60
Maximum Loss, Percent
Figure 27. Frequency distribution of AASHTO T96 specifications.
TABLE 15 AASHTO T96 specifications for states with multiple levels
Agency Maximum Loss (%) by AASHTO T96
Kentucky 40 for most, 50 for sandstone and 60 for slag
Rhode Island 40 for friction course, 50 for others
South Dakota 45 3
M. ESALs
Utah 35 for Category 1 and 40 for Category 2 Routes
Wyoming 35 or 40 depending on class
