The National Academies Press

Currently Skimming:

Pages 8-28

The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.

From page 8... ... 8 2.1 Introduction Both short- and long-term performance of any constructed pavement system largely depends on the quality of materials used in different layers. To ensure adequate performance of pavements under traffic loading and environmental conditions, transportation agencies have developed specifications to check source properties considering aggregate quality. Read the entire page →
From page 9... ... Aggregate Sources, Recycling, and Blending 9 Intrusive igneous rocks have a chance to grow large enough minerals to give it a coarsegrained texture, whereas extrusive igneous rocks cool more rapidly and can be more fine grained. Igneous rocks often have high amounts of silica. Read the entire page →
From page 10... ... 10 Aggregate Quality Requirements for Pavements provinces) reported that they do not have any approved lists of aggregates. Read the entire page →
From page 11... ... Aggregate Sources, Recycling, and Blending 11 respondents (26 U.S. DOTs and five Canadian provinces) Read the entire page →
From page 12... ... 12 Aggregate Quality Requirements for Pavements (river) deposits. Read the entire page →
From page 13... ... Aggregate Sources, Recycling, and Blending 13 2.3 Aggregate Applications in Pavement Construction As discussed in Section 1.1, many highway agencies have already established certain aggregate quality requirements associated with specific applications of aggregates in pavement construction. Accordingly, transportation agencies were asked to indicate which pavement layers are constructed with specific aggregate quality requirements. Read the entire page →
From page 14... ... 14 Aggregate Quality Requirements for Pavements As part of the questionnaire, the frequency in utilizing different aggregate sources in pavement construction was investigated. Figure 2-6 summarizes transportation agency responses, in which 94% indicated the use of RAP and almost 70% indicated the utilization of blended virgin aggregate sources. Read the entire page →
From page 15... ... Aggregate Sources, Recycling, and Blending 15 • For coarse aggregates, AASHTO T 85 or ASTM C127, Standard Method of Test for Specific Gravity and Absorption of Coarse Aggregate, is used. For example, Oklahoma DOT requires this test to be conducted on coarse aggregates at the quarries in order to qualify these materials to be used in construction projects (Oklahoma DOT 2016) Read the entire page →
From page 16... ... 16 Aggregate Quality Requirements for Pavements Test methods are used for determining the quality of fines or finer particles (e.g., plasticity and degradation) and the quantities of deleterious materials in aggregates such as highly reactive clays, organic matter, and friable particles. Read the entire page →
From page 17... ... Aggregate Sources, Recycling, and Blending 17 and five Canadian provinces) reported that they do not. Read the entire page →
From page 18... ... 18 Aggregate Quality Requirements for Pavements coating and morphology. Particle size and shape properties, amount of asphalt coating the RAP particles, and the binder content of the RAP are among the important engineering properties that control the quality of this material. Read the entire page →
From page 19... ... Aggregate Sources, Recycling, and Blending 19 quality-related properties that are investigated by respondent agencies. Some agencies mentioned other quality-related properties associated with utilization of RAP that are listed as follows: • Effective specific gravity backcalculated from theoretical maximum specific gravity (Rice method) Read the entire page →
From page 20... ... 20 Aggregate Quality Requirements for Pavements Magnesium Sulfate (ACI 2001) Read the entire page →
From page 21... ... Aggregate Sources, Recycling, and Blending 21 2.4.4 Quality-Related Source Properties of Artificial/Byproduct Aggregates Common byproduct materials used in pavement applications are SFS, BFS, and QB. Ferrous slags (e.g., SFS and BFS) Read the entire page →
From page 22... ... 22 Aggregate Quality Requirements for Pavements the Expanded Shale, Clay and Slate Institute (ESCSI) , LWA use in chip seals, compared with conventional aggregates, results in safer, cheaper, and longer lasting seal coats. Read the entire page →
From page 23... ... Aggregate Sources, Recycling, and Blending 23 gravity, freeze-thaw resistance, and expansion properties were the common quality properties that were tested or screened. Note that expansion properties here refer to general expansion regardless of use in PCC or HMA. Read the entire page →
From page 24... ... 24 Aggregate Quality Requirements for Pavements performance in field has been reported. Therefore, some agencies do not consider the degradation requirements based on LAA testing for utilization of BFS [Recycled Materials Resource Center (RMRC) Read the entire page →
From page 25... ... Aggregate Sources, Recycling, and Blending 25 mixed at various percentages with the DGABC to evaluate whether an optimum mix blend could be formulated. They reported that RAP, RCA, and DGABC-blended materials obtained higher resilient modulus values than the currently used virgin aggregates, while RCA mixed samples resulted in the lowest amount of permanent deformation. Read the entire page →
From page 26... ... 26 Aggregate Quality Requirements for Pavements hand, does not allow blending any two aggregate sources for mineral fillers used in HMA mixes and limits the usage to one mineral filler source per HMA design (Kansas DOT 2015) Read the entire page →
From page 27... ... Aggregate Sources, Recycling, and Blending 27 95% 38% 80% 28% 3% 38 15 32 11 1 0 10 20 30 40 0% 20% 40% 60% 80% 100% Virgin + Virgin Virgin + Marginal Virgin + Recycled (RAP or RCA or artificial aggregates) Virgin + Quarry Byproduct Other Number of Responses Percentage of Survey Respondents 40 survey respondents Figure 2-14. Read the entire page →
From page 28... ... 28 Aggregate Quality Requirements for Pavements Transportation Agency Restriction Considering Quality Concerns Alaska Up to 10% by weight crushed glass (cullet) smaller than 3/8 in. Read the entire page →

From page 8...

... 8 2.1 Introduction Both short- and long-term performance of any constructed pavement system largely depends on the quality of materials used in different layers. To ensure adequate performance of pavements under traffic loading and environmental conditions, transportation agencies have developed specifications to check source properties considering aggregate quality.