A technique for measuring radial deformation during repeated load triaxial testing

1978 ◽  
Vol 15 (3) ◽  
pp. 426-429 ◽  
Author(s):  
David M. Cole
Keyword(s):  
Test Data ◽  
Poisson’S Ratio ◽  
Operating Principle ◽  
Poisson's Ratio ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Radial Deformation ◽  
Repeated Load ◽  
Displacement Transducers ◽  
Repeated Load Triaxial

A system of non-contacting displacement transducers has been used to record radial deformation in repeated load triaxial tests. Operating principle, system capabilities, and installation technique are discussed. Results of tests on clay and silt subgrade materials are presented and Poisson's ratio is calculated directly from test data.

Geogrid Stabilization of Unbound Aggregates Evaluated Through Bender Element Shear Wave Measurement in Repeated Load Triaxial Testing

2020 ◽  
Vol 2674 (3) ◽  
pp. 113-125
Author(s):  
Mingu Kang ◽  
Joon Han Kim ◽  
Issam I. A. Qamhia ◽  
Erol Tutumluer ◽  
Mark H. Wayne
Keyword(s):  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Resilient Modulus ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Bender Element ◽  
Wave Measurement ◽  
Repeated Load ◽  
Repeated Load Triaxial

This paper describes the use of the bender element (BE) shear wave measurement technology for quantifying the effectiveness of geogrid stabilization of unbound aggregate materials with improved mechanical properties from repeated load triaxial testing. Crushed stone aggregate specimens were prepared with three different gradations, that is, upper bound (UB), mid-range engineered (ENG), and lower bound, according to the dense graded base course gradation specification in Illinois. The specimens were compacted at modified Proctor maximum dry densities and optimum moisture contents. Two geogrids with different triaxial aperture sizes were placed at specimen mid-height, and unstabilized specimens with no geogrid were also prepared for comparison. To measure shear wave velocity, three BE pairs were placed at different heights above geogrid. Repeated load triaxial tests were conducted following the AASHTO T307 standard resilient modulus test procedure, while shear wave velocity was measured from the installed BE pairs. After initial specimen conditioning, and at low, intermediate, and high applied stress states, both the resilient moduli and accumulated permanent strains were determined to relate to the geogrid local stiffening effects in the specimens quantified by the measured shear wave velocities. The resilient modulus and shear wave velocity trends exhibited a directly proportional relationship, whereas permanent strain and shear wave velocity values were inversely related. The enhancement ratios calculated for the geogrid stabilized over the unstabilized specimens showed significant improvements in mechanical behavior for the UB and ENG gradations, and a maximum enhancement was achieved for the engineered gradation specimens stabilized with the smaller aperture geogrid.

Assessment of On-Sample Instrumentation for Repeated Load Triaxial Tests

1998 ◽  
Vol 1614 (1) ◽  
pp. 52-60 ◽  
Author(s):  
Andrew R. Dawson ◽  
Simon D. Gillett
Keyword(s):  
Granular Materials ◽  
Comparative Studies ◽  
Measurement Process ◽  
Triaxial Tests ◽  
Triaxial Testing ◽  
Unbound Granular Materials ◽  
Repeated Load ◽  
Pavement Construction ◽  
Repeated Load Triaxial

Five laboratories have been involved in a series of comparative studies of the repeated load triaxial testing of soils and unbound granular materials as found in the lower layers of pavement construction. These comparisons with soil, granular materials, and an artificial specimen are outlined. The performance of the varied types of instruments that measure both axial and radial deformations is assessed, with particular attention to the fixing arrangements, instrument limitations, and weight. On the basis of the information presented, recommendations are given about the most appropriate types of instrument. No universal type is recommended, and it is clear that some variation in performance is an inevitable consequence of the measurement process.

Granular Material Radial Deformation Measurements with a Circumferential Extensometer in Repeated Load Triaxial Testing

1998 ◽  
Vol 1614 (1) ◽  
pp. 61-69 ◽  
Author(s):  
Erol Tutumluer ◽  
Navneet Garg ◽  
Marshall R. Thompson
Keyword(s):  
Granular Material ◽  
Material Behavior ◽  
Measuring System ◽  
Triaxial Testing ◽  
Radial Deformation ◽  
Nonlinear Stress ◽  
Wheel Loading ◽  
Repeated Load ◽  
Stress Dependent ◽  
Repeated Load Triaxial

Determination of both axial and radial specimen strains in a repeated load triaxial test is essential for properly characterizing the directional dependency of resilient granular material behavior. Radial deformation measurement is not yet included in the standard AASHTO test procedure. The method of measuring radial strains adopted in this study emphasizes the use of a contact-type specimen instrumentation technique with a circumferential chain extensometer. The circumferential extensometer was successfully used in repeated load triaxial testing to measure radial strains of three aggregate samples with different material types and properties. The accuracy of the measuring system was within 10−5 (in strains) when the smallest strains recorded were on the order of 10−4. Nonlinear stress-dependent models for properly characterizing the anisotropic granular material stiffnesses were developed from measured axial and radial strains. The vertical/horizontal stiffness ratios in the triaxial sample consistently increased with increasing principal stress ratios, which often occurs in pavements under wheel loading. In general, the repeatability in radial strain measurements was deemed to be satisfactory and more reliable strains were measured at low confining pressures.

Repeated Load Triaxial Tests on a Dolomite Ballast

1978 ◽  
Vol 104 (7) ◽  
pp. 1013-1029
Author(s):  
Gerald Patrick Raymond ◽  
David R. Williams
Keyword(s):  
Triaxial Tests ◽  
Repeated Load ◽  
Repeated Load Triaxial

Geotechnical characteristics of recycled crushed brick blends for pavement sub-base applications

2012 ◽  
Vol 49 (7) ◽  
pp. 796-811 ◽  
Author(s):  
A. Arulrajah ◽  
J. Piratheepan ◽  
M.W. Bo ◽  
N. Sivakugan
Keyword(s):  
Recycled Concrete ◽  
Engineering Properties ◽  
Triaxial Tests ◽  
Crushed Rock ◽  
Dry Density ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Crushed Brick ◽  
Repeated Load ◽  
Repeated Load Triaxial

This paper presents the findings of a laboratory investigation on the characterization of recycled crushed brick when blended with recycled concrete aggregate and crushed rock for pavement sub-base applications. The engineering properties of the crushed brick blends were compared with typical state road authority specifications in Australia for pavement sub-base systems to ascertain the potential use of crushed brick blends in these applications. The experimental programme included particle-size distribution, modified Proctor compaction, particle density, water absorption, California bearing ratio (CBR), Los Angeles abrasion, pH, organic content, and repeated load triaxial tests. Laboratory tests were undertaken on mixtures of 10%, 15%, 20%, 25%, 30%, 40%, and 50% crushed brick blended with recycled concrete aggregate or crushed rock. The research indicates that up to 25% crushed brick could be safely added to recycled concrete aggregate and crushed rock blends in pavement sub-base applications. The repeated load triaxial test results on the blends indicate that the effects of crushed brick content on the mechanical properties in terms of permanent deformation and resilient modulus of both the recycled concrete aggregate and crushed rock blends were marginal compared to the effects on dry density and moisture content.

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