Improved Test Methods for Specific Gravity and Absorption of Coarse and Fine Aggregate (2015) / Chapter Skim
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Pages 53-63
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From page 53... ...
53 Ruggedness Study Plan The objective of this ruggedness study was to evaluate the sensitivity of the proposed test methods to the changes in levels of operating and environmental factors. The results of ruggedness testing were used to eliminate or reduce the sources of variation, which would ensure better precision of test results and establish appropriate ranges of operating parameters for standardizing the test methods.
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From page 54... ...
54 ID Variable AASHTO T 85 Requirement Comments Low Value High Value A Section 7.2 – Aggregate size Test materials retained on the No. 4 sieve Some aggregates contain significant amount of material finer than No.
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From page 55... ...
55 test results, the difference between the minimum and maximum levels of the factor would be reduced. Experimental Design for Ruggedness Testing For ruggedness testing, test data were collected for specific combinations of the variable factors and their levels.
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56 No. Factor Determinations (Test Combinations)
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57 homogeneous. After the samples had been prepared, sample numbers were randomized utilizing the same procedure used for proficiency samples before they were sent to the testing laboratories.
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58 Absorption Level Material Lab Avg. Absorption A B C D E F G < 2% Granite AAPRL 0.5% NS NS NS NS NS 8.9 NS NCAT 0.5% NS NS NS NS NS NS NS NIST 0.5% NS NS NS NS NS NS NS Gravel AAPRL 1.4% 6.2 NS NS 9.9 NS 11.0 NS NCAT 1.4% NS NS NS NS NS NS NS NIST 1.4% 13.4 16.3 NS NS NS 19.6 NS 2% AL-LMS AAPRL 2.3% NS NS NS NS NS NS NS NCAT 2.3% NS NS NS NS NS 6.3 NS NIST 2.3% NS NS NS NS 7.6 NS NS AL-Slag AAPRL 2.7% NS NS NS NS 8.8 NS NS NCAT 2.7% NS NS NS NS NS NS NS NIST 2.7% NS NS NS NS NS NS NS Table 4-11.
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From page 59... ...
59 Section 7.2 yield statistically different water absorption results for low absorption (< 2 percent) coarse aggregates.
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60 room temperature. This is to avoid thermal shock that may cause differential contraction in the hot aggregate particles.
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61 show F-statistics for Gsb, Gssd, Gsa, and water absorption of the four fine aggregates, respectively. In these tables, NS means "Not Significant," and the shaded cells show the F-values exceeding the critical F-value of 5.59.
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From page 62... ...
Absorption Level Material Lab Avg. Absorption A B C D E F G < 2% Granite AAPRL 0.4% 73.8 107.6 NS 184.9 18.7 22.9 231.7 NCAT 0.4% 21.9 NS NS NS NS NS NS NIST 0.4% 12.9 NS NS NS NS NS 9.3 LS-105 AAPRL 1.4% 240.0 NS 15.2 75.7 NS 0.9 120.8 NCAT 1.4% 24.1 NS NS 11.2 NS NS NS NIST 1.4% 55.3 13.0 NS 12.3 NS NS 114.8 2% AL-LMS AAPRL 2.2% 95.0 31.5 11.3 124.9 NS NS 46.3 NCAT 2.2% 51.7 30.2 6.9 10.2 NS NS 5.7 NIST 2.2% 47.1 22.7 NS 52.2 NS NS NS AL-Slag AAPRL 2.2% 846.2 150.6 NS 96.7 NS 13.2 193.9 NCAT 2.2% 98.1 NS NS 34.6 NS NS 26.2 NIST 2.2% 186.3 18.9 NS 63.2 NS 13.6 158.5 Table 4-20.
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From page 63... ...
63 • If the P200 portion is tested separately, it can be dry-sieved or washed out of the fine aggregate sample. However, the agency's and contractor's laboratories should use the same method for separating the P200 fraction.
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