Charles W. Schwartz - The University of Maryland Dr. Charles W. Schwartz is a professor and chair of Civil and Environmental Engineering at the University of Maryland, College Park. His teaching and research activities encompass pavement design and analysis, advanced soil mechanics, computational geomechanics/pavement mechanics, and material characterization and constitutive modeling. He has played leadership roles in many national research projects and regularly assists federal, state, and local agencies and private firms on pavement-related topics. He is a member of TRB (Chair, AFD80-Strength and Deformation Characteristics of Pavement Layers, ASCE (Chair, Geo-Institute Pavements Committee), AAPT, and ISAP and serves on the editorial boards of the International Journal of Pavement Engineering and Transportation Geotechnics. He is a co-developer and lead instructor of the NHI course Geotechnical Aspects of Pavements. Monday, February 29, 2016 | 11:00 a.m. - 12:00 p.m. 410 Hitchcock Hall STIFFNESS-BASED COMPACTION QUALITY ASSURANCE TESTING USING LIGHTWEIGHT DEFLECTOMETERS Charles W. Schwartz, PhD Professor and Chair, Department of Civil and Environmental Engineering University of Maryland - College Park The Department of Civil, Environmental and Geodetic Engineering Compaction control using lightweight deflectometers (LWD) is currently being evaluated in several states and countries and fully implemented for pavement construction quality assurance (QA) by a few. Broader implementation has been hampered by the lack of a widely recognized standard for interpreting the load and deflection data obtained during construction QA testing. More specifically, reliable and practical procedures are required for relating these measurements to the fundamental material property—resilient modulus—used in pavement design. Modulus or stiffness-based QA for pavement construction requires two components: (1) a target resilient modulus value to be achieved after compaction; and (2) a procedure for determining the resilient modulus achieved in-place. The target resilient modulus can be defined as the value used in pavement structural design, tempered by what is achievable for a given material. Achievable values for resilient modulus for a material can be determined by laboratory testing with adjustments for the density, moisture, and traffic-induced stress levels expected in the field. LWDs can be used to determine in-place stiffness, but only after correcting for moisture/drying effects, stress levels, and finite layer effects. e The objective of this study is to develop a straightforward procedure for using LWD for modulus/stiffness-based compaction control that is suitable for practical implementation by field inspection personnel. This procedure must: (1) fully account for the influence of moisture on LWD measurements, (2) include the effects of stress state on measured modulus and the differences between the LWD induced stress state and the stress states induced by design traffic loads, (3) be applicable to LWD testing of half-space (i.e., subgrade) and finite thickness layered conditions (i.e., granular base layers); and (4) be able to account for individual LWD device details - e.g., plate diameter, plate rigidity, contact area stress distribution, loading rate, deflection measurement location(s). stress states induced by design traffic loads, (3) be applicable to LWD testing of half-space (i.e., subgrade) and finite Abstract

STIFFNESS-BASED COMPACTION QUALITY ASSURANCE … · Modulus or stiffness-based QA for pavement construction requires two components: (1) a target resilient modulus value to be achieved

Download PDF Report

Upload
others
View
5
Download
0

Embed Size (px)

Citation preview

Page 1: STIFFNESS-BASED COMPACTION QUALITY ASSURANCE … · Modulus or stiffness-based QA for pavement construction requires two components: (1) a target resilient modulus value to be achieved

He has played leadership roles in many national research projects and regularly assists federal, state, and local agencies and private firms on pavement-related topics. He is a member of TRB (Chair, AFD80-Strength and Deformation Characteristics of Pavement Layers, ASCE (Chair, Geo-Institute Pavements Committee), AAPT, and ISAP and serves on the editorial boards of the International Journal of Pavement Engineering and Transportation Geotechnics. He is a co-developer and lead instructor of the NHI course Geotechnical Aspects of Pavements.

Monday, February 29, 2016 | 11:00 a.m. - 12:00 p.m. 410 Hitchcock Hall

STIFFNESS-BASED COMPACTION QUALITY ASSURANCE TESTING USING LIGHTWEIGHT DEFLECTOMETERS

Charles W. Schwartz, PhDProfessor and Chair, Department of Civil and Environmental Engineering

University of Maryland - College Park

The Department of Civil, Environmental and Geodetic Engineering

Compaction control using lightweight deflectometers (LWD) is currently being evaluated in several states and countries and fully implemented for pavement construction quality assurance (QA) by a few. Broader implementation has been hampered by the lack of a widely recognized standard for interpreting the load and deflection data obtained during construction QA testing. More specifically, reliable and practical procedures are required for relating these measurements to the fundamental material property—resilient modulus—used in pavement design. Modulus or stiffness-based QA for pavement construction requires two components: (1) a target resilient modulus value to be achieved after compaction; and (2) a procedure for determining the resilient modulus achieved in-place. The target resilient modulus can be defined as the value used in pavement structural design, tempered by what is achievable for a given material. Achievable values for resilient modulus for a material can be determined by laboratory testing with adjustments for the density, moisture, and traffic-induced stress levels expected in the field. LWDs can be used to determine in-place stiffness, but only after correcting for moisture/drying effects, stress levels, and finite layer effects.eThe objective of this study is to develop a straightforward procedure for using LWD for modulus/stiffness-based compaction control that is suitable for practical implementation by field inspection personnel. This procedure must: (1) fully account for the influence of moisture on LWD measurements, (2) include the effects of stress state on measured modulus and the differences between the LWD induced stress state and the stress states induced by design traffic loads, (3) be applicable to LWD testing of half-space (i.e., subgrade) and finite thickness layered conditions (i.e., granular base layers); and (4) be able to account for individual LWD device details - e.g., plate diameter, plate rigidity, contact area stress distribution, loading rate, deflection measurement location(s). stress states induced by design traffic loads, (3) be applicable to LWD testing of half-space (i.e., subgrade) and finite

Abstract