00677573

Component

http://onlinepubs.trb.org...trr/1994/1462/1462-001.pdf

https://scholar.google.co...lson&publication_year=1994

Construction control for engineered fills is usually provided by a specification requirement that the in-place dry density of the fill be at least a specified percentage of a reference dry density. The reference dry density is usually measured by a laboratory compaction test, such as the ASTM D698 (Standard Proctor) moisture-density relationship test. The use of laboratory determination of the reference dry density for construction control is based on the implicit assumption that the material compacted in the lab is substantially equivalent to the material compacted in the field. However, when the fill material contains gravel (material coarser than the No. 4 sieve), this assumption is generally not correct. Therefore the contractor and engineer must rely on experience with the performance of high gravel content fills at certain specified percentages of a reference dry density, selecting specification requirements appropriate to individual circumstances. Several methods are available to account for the effect of the coarse fraction on the reference dry density, including various rock correction equations and laboratory scalp-and-replace techniques. Each method may provide a different reference dry density. The impact of the rock-correction method on construction control is addressed. The results of a survey of several large construction companies in the southwestern United States revealed that contractors have a great deal of experience with scalp-and-replace rock correction methods and apparently not as much experience with rock correction equations, particularly in highway work. Although contractors may tend to have most of their experience with scalp-and-replace methods, many engineering testing firms tend toward the use of rock correction equations. Given the significant variation in computed relative compaction that can arise from the different rock correction methods, well-written compaction specifications for high gravel content soils, explicitly stating the technique for rock correction in compaction control, are a must. An understanding of the potential differences in rock correction methods, by contractors and engineers alike, should reduce conflicts and future problems with the compacted fill.

This paper appears in Transportation Research Record No. 1462, Compaction of Difficult Soils and Resilient Modulus Testing. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved

01495760

English

p. 3-9

1994

Transportation Research Record

0309060680

Figures (4) ; References (6) ; Tables (2)

Compaction; Construction management; Fills; Gravelly soils; Specifications

Construction; Geotechnology; Highways; I42: Soil Mechanics

TRIS, TRB

May 2 1995 12:00AM

• ACCURACY IMPROVEMENT OF EXTERNAL RESILIENT MODULUS MEASUREMENTS USING SPECIMEN GROUTING TO END PLATENS
• ANALYSIS OF PROCEDURES FOR ESTABLISHING IN SITU SUBGRADE MODULI
• BEHAVIOR OF EXPANDED POLYSTYRENE BLOCKS
• COMPACTED CLAY EMBANKMENT FAILURES
• COMPACTION CONTROL CRITERIA FOR CLAY HYDRAULIC BARRIERS
• COMPACTION SPECIFICATIONS FOR LOW HYDRAULIC CONDUCTIVITY CLAY EMBANKMENTS
• FACTORS INFLUENCING DETERMINATION OF A SUBGRADE RESILIENT MODULUS VALUE
• INFLUENCE OF TESTING PROCEDURE AND LVDT LOCATION ON RESILIENT MODULUS OF SOILS
• INVESTIGATION OF ROAD WIDENING ON SOFT SOILS USING A SMALL CENTRIFUGE
• RESILIENT MODULI OF AGGREGATE MATERIALS: VARIABILITY DUE TO TESTING PROCEDURE AND AGGREGATE TYPE
• RESILIENT MODULUS OF SUBGRADE SOILS: COMPARISON OF TWO CONSTITUTIVE EQUATIONS