01562968

Monograph

http://www.trb.org/Main/Blurbs/172541.aspx

Design and production of paving asphalt and portland cement concrete (PCC) mixtures rely on accurate, precise measurement of aggregate specific gravity and absorption. Aggregate specific gravities are needed to calculate the voids in mineral aggregate (VMA) and effective binder content of asphalt mixtures, which are key volumetric properties used in mix design and acceptance testing. For PCC, aggregate absorption is used to adjust water/ cement or water/cementitious material ratios which affect the workability of PCC and are a good indicator of PCC’s resistance to freezing and thawing and PCC’s durability. The current AASHTO standard test methods for aggregate specific gravity and absorption, namely, T 84, Specific Gravity and Absorption of Fine Aggregate, and T 85, Specific Gravity and Absorption of Coarse Aggregate, share several shortcomings in terms of subjectivity of the measurements, time requirements for conditioning and testing, and precision. The objective of NCHRP Project 4-35 was to develop test methods for determining the specific gravity and absorption of coarse and fine aggregates with improved accuracy, precision, ease of use, and time required for conditioning and testing, compared to the current AASHTO T 84 and T 85 methods. The key outcome of the research is the finding that AASHTO T 85 with several proposed changes, AASHTO T 84 (modified to remove and separately test P200 material), and ASTM D7172 (Standard Test Method for Determining the Relative Density (Specific Gravity) and Absorption of Fine Aggregates Using Infrared) provide a good balance of accuracy and precision compared to the other methods evaluated, including the current AASHTO T 85 and T 84. This finding was developed through a critical literature review on the basis of which an initial set of ten test methods was selected for evaluation in a series of five laboratory experiments and a ruggedness study. This report fully documents the research and includes the following two appendixes: Revised AASHTO T 85 and Revised AASHTO T 84 In addition, seven appendixes are available to download from the NCHRP Project 4-35 web page at http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=1614. These appendixes summarize the literature review, testing results of the experiments, and results of a ruggedness study.

Project 04-35

English

105p

2015

NCHRP Report

9780309308533

Print

Appendices; Bibliography; Figures; Tables

Absorption; Coarse aggregates; Fine aggregates; Paving materials; Specific gravity; Standards; Test procedures

Ruggedness

Highways; Materials; Pavements; I36: Aggregates

TRIS, TRB, ATRI

May 15 2015 10:49AM