Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 64
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