Author: Chwen-Jang LiawPublisher:
ISBN:
Category :
Languages : en
Pages : 400
Book Description
Effects of Temperature on the Fracture Behavior of Early Aged Concrete Pavements and Asphalt Concrete Overlays
Author: Chwen-Jang LiawA Guide to Evaluating Thermal Effects in Concrete Pavements
Author: Per Just AndersenPublisher:
ISBN:
Category : Concrete
Languages : en
Pages : 118
Book Description
This report describes the use of tables developed to help determine problems that may result from early thermal effects in concrete. The thermal behavior of concrete can be estimated from a knowledge of concrete temperature, air temperature, type of cement, and content of cement in the mixture. The thermal effects tables can be used to predict whether too high a temperature will be reached in the pavement; whether early thermal cracking will result from larger differences between the temperature of the concrete slab and the temperature of either the air or the base; or whether there is a risk of early cracking of the concrete. Examples of the use of the table are given along with guidelines for avoiding undesirable thermal effects.
Early-age Concrete Temperature and Moisture Relative to Curing Effectiveness and Projected Effects on Selected Aspects of Slab Behavior
Author: Dan YePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Concrete curing has long been realized to be important to produce durable concrete. Curing compound is widely used to cure concrete in the field. The current curing membrane evaluation method ASTM C 156, however, is incapable of distinguishing the curing compound quality and guiding the curing practice in the field. A new laboratory curing membrane evaluation protocol is developed in this study. It has the ability to rank the quality of curing compound and guide curing practice in the field according to the field ambient weather conditions and the type of curing compound. A series of field tests were conducted to investigate the key factors that affect the curing effectiveness in the field conditions. A finite element program, temperature and moisture analysis for curing concrete (TMAC2), is updated to solve the coupled and nonlinear heat transfer and moisture transport problems in early-age concrete. Moisture capacity is induced into the TMAC2, which makes it unique to characterize the self-desiccation. A full scale concrete pavement test study was conducted at the FAA National Airport Pavement Test Facility (NAPTF) near Atlantic City, New Jersey. In this study, the material properties, i.e. thermal conductivity and moisture diffusivity, were backcalculated from field data. Thereafter, backcalculated material properties were used to forward-calculate the temperature and moisture histories of all other sections. High order shear deformable theory is used to model the concrete slab curling and warping behavior because of highly nonlinear temperature and moisture gradients. The maximum shear strain is obtained a couple of inches below the concrete slab. This might account for the occurrence of delamination.
Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements
Author: William G. ButtlarPublisher: Springer
ISBN: 3319768492
Category : Technology & Engineering
Languages : en
Pages : 256
Book Description
Premature cracking in asphalt pavements and overlays continues to shorten pavement lifecycles and creates significant economic and environmental burden. In response, RILEM Technical Committee TC 241-MCD on Mechanisms of Cracking and Debonding in Asphalt and Composite Pavements has conducted a State-of-the-Art Review (STAR), as detailed in this comprehensive book. Cutting-edge research performed by RILEM members and their international partners is presented, along with summaries of open research questions and recommendations for future research. This book is organized according to the theme areas of TC 241-MCD - i.e., fracture in the asphalt bulk material, interface debonding behaviour, and advanced measurement systems. This STAR is expected to serve as a long term reference for researchers and practitioners, as it contributes to a deeper fundamental understanding of the mechanisms behind cracking and debonding in asphalt concrete and composite pavement systems.
Fracture Characterization of Thin Bonded Asphalt Concrete Overlay Systems
Author: Sarfraz AhmedPublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Asphalt overlays provide an economical means for treating deteriorated pavements. Thin bonded overlay (TBO) systems have become popular options for pavement rehabilitation. In addition to functional improvements, these systems ensure a high degree of waterproofing benefits. Conventional asphalt concrete fracture tests were developed for pavements with homogeneous asphalt concrete mixtures, and typically their thicknesses exceed two inches. The use of spray paver technology for construction of TBO leads to continuously varying asphalt binder content, up to approximately one-third of the layer thickness. The graded properties of asphalt concrete and thickness of the TBO (typically less than 50 mm) pose challenges for the use of conventional fracture test geometries. For example, obtaining the beams for SEN[B] specimens from pavement may not practical because of insufficient layer thickness of the TBO or may lead to excessive pavement damage. Applications of the other established test geometries, the DC[T] and SC[B] tests, are limited because of the material nonhomogeneity caused by nonuniform distribution of asphalt binder and smaller as-constructed thicknesses of TBO, which are usually less than 25 mm (1 inch) for gap-graded and 50 mm (2 inch) for dense-graded hot mix asphalt (HMA) mixtures. Both the DC[T] and SC[B] tests simulate movement of the crack fronts in transverse or longitudinal directions in the pavement. Use of these tests on field-procured samples of TBO yields a crack front that encounters nonhomogeneous material through the specimen thickness. The crack moves perpendicular to the axis of material nonhomogeneity, which makes data interpretation and fundamental material fracture characterization challenging. In addition, the crack in the specimens is correlated to a crack channeling across the pavement width rather than a more anticipated bottom-up or top-down direction. New test procedures for fracture characterization of graded asphalt pavement systems that have significant material property gradients through their thicknesses have been proposed. Suitable specimen geometry and testing procedures were developed using ASTM E399 and ASTM D7313-07 as a starting point. Laboratory tests were performed using an optimized compact tension C[T] test geometry for field cores as well as laboratory-fabricated composite specimens. Laboratory testing using the proposed procedure clearly showed distinction in the fracture characteristics for specimens prepared with varying material compositions. This capability of distinguishing different materials combined with stable crack growth makes the proposed testing procedure ideal for fracture characterization of thin and graded pavement systems. Statistical analysis of test data revealed that the proposed C[T] test procedure is capable of detecting differences in fracture energy results across a wide range of pavement systems and yields a low test variability. Finite element simulations of the test procedure further indicate the suitability of the test procedure as well as demonstrate a procedure for extraction of fundamental material properties. The suitability of the proposed C[T] test in the context of warmer temperatures was also evaluated. Changes in the loading rate were suggested to minimize the creep energy dissipation during the test at different test temperatures. Composite specimen fabrication procedure has been developed to optimize the design of TBOs. The proposed procedure can also be used to prepared composite specimens for interface bond strength and rutting resistance tests with emulsion and asphalt cement as tack coat material. Suggested wet application of tack coat emulsion on textured base, compacted with heated Superpave gyratory compactor top plate closely resembles field installation of TBOs. Moreover tack coat emulsion permeation effects on mixture fracture and bulk properties were also evaluated in an experimental study. Image analysis technique was utilized to characterize the tack coat emulsion impregnation gradient through the thickness of the overlays. An integrated approach to predict cracking performance of TBOs was presented combining laboratory test results, numerical simulations and early field performance.
Prevention of Thermal Cracking in Concrete at Early Ages
Author: R. SpringenschmidPublisher: CRC Press
ISBN: 1482271818
Category : Architecture
Languages : en
Pages : 365
Book Description
An important new report from the RILEM Technical Committee 119. This book presents models and methods to determine thermal stresses and cracking risks in concrete. The possible influences on and causes of thermal cracking of concrete are discussed and cases of practical measures for avoiding cracking are detailed.
Pavement Engineering
Author: Rajib B. MallickPublisher: CRC Press
ISBN: 1439870357
Category : Technology & Engineering
Languages : en
Pages : 697
Book Description
Pavements are engineered structures essential to transportation, commerce and trade, and everyday life. In order for them to perform as expected, they must be designed, constructed, maintained, and managed properly. Providing a comprehensive overview of the subject, Pavement Engineering: Principles and Practice, Second Edition covers a wide range of topics in asphalt and concrete pavements, from soil preparation to structural design and construction. This new edition includes updates in all chapters and two new chapters on emerging topics that are becoming universally important: engineering of sustainable pavements and environmental mitigation in transportation projects. It also contains new examples and new figures with more informative schematics as well as helpful photographs. The text describes the significance of standards and examines traffic, drainage, concrete mixes, asphalt binders, distress and performance in concrete and asphalt pavements, and pavement maintenance and rehabilitation. It also contains a chapter on airport pavements and discusses nondestructive tests for pavement engineering using nuclear, deflection-based, electromagnetic, and seismic equipment. The authors explore key concepts and techniques for economic analysis and computing life-cycle cost, instrumentation for acquiring test data, and specialty applications of asphalt and concrete. The Second Edition includes more relevant issues and recently developed techniques and guidelines for practical problems, such as selection of pavement type, effect of vehicle tires, and use of smart sensors in rollers and software for drainage analysis. This book presents in-depth, state-of-the-art knowledge in a range of relevant topics in pavement engineering, with numerous examples and figures and comprehensive references to online resources for literature and software. It provides a good understanding of construction practices essential for new engineers and materials processing and construction needed for solving numerous problems.
Temperature effects in compacting an asphalt concrete overlay
Author: Robert A. EatonThermal Behavior of Crumb-rubber Modified Asphalt Concrete Mixtures
Author: Amy Epps MartinPublisher:
ISBN:
Category : Asphalt concrete
Languages : en
Pages : 826
Book Description
Author: Hak-Chul Shin