Characterization and Modeling of Shrinkage Cracking of Cementitiously Stabilized Layers in Pavement PDF Download
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Author: Jingan Wang
Publisher:
ISBN: 9781303466090
Category :
Languages : en
Pages :
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Book Description
It is found that neither the existing models nor the developed mechanistic based models can predict crack spacing and width in the field. Empirical shrinkage crack spacing and width models are developed based on dimensional analysis using field data.
Author: Jingan Wang
Publisher:
ISBN: 9781303466090
Category :
Languages : en
Pages :
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Book Description
It is found that neither the existing models nor the developed mechanistic based models can predict crack spacing and width in the field. Empirical shrinkage crack spacing and width models are developed based on dimensional analysis using field data.
Author: Stephanus Johannes Hofmeyr Louw
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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This dissertation considers the effects of microcracking and improved mix design procedures on drying shrinkage cracks in full depth reclaimed pavement layers stabilized with cement (FDR-PC). The hypotheses for this dissertation are: •Microcracking can mitigate the effects of drying shrinkage cracking by inducing a network of hairline cracks to relieve the restraint stress to minimize drying shrinkage crack widths. •Improved mix design and laboratory characterization methods can increase the effective fatigue life of a full depth reclaimed layer stabilized with portland cement (FDR-PC) by accepting the presence of drying shrinkage cracks in the layer, and focusing the mix design to minimize the effects of these cracks. These hypotheses were developed from forensic investigation results of drying shrinkage cracking and fatigue cracking of the FDR-PC test track at the University of California Pavement Research Center (UCPRC), and previous research on accelerated pavement testing of cement stabilized based layers. The research approach to investigate these hypotheses consisted of: •A literature review that provided an initial basis for the work. •Extensive field investigations that were used to develop an updated proposed understating of how cement stabilized layers fail. •The evaluation of microcracking on a controlled experimental test road and its effects on reflective drying shrinkage cracks. •Laboratory testing to simulate microcracking.•Theoretical simulation of microcracking using the field and laboratory inputs. The research was based on the observation that cement stabilized layers do not fail uniformly along the pavement and that the rate of failure is dependent on the crack widths. Cement stabilized layers are often cracked from drying shrinkage creating a series of large blocks in the road. Cement stabilized layers have a range of expected effective fatigue lives along the pavement: the shortest around the widest cracks, and the longest where the slabs are intact. Through the research in this dissertation, it was shown that microcracking reduces the resistance to shrinkage cracking of the FDR-PC at the time of microcracking and forces the development of additional drying shrinkage cracks. This distributes the total drying shrinkage strain over more cracks and minimizes the accumulation of shrinkage strain at each drying shrinkage crack, reducing crack widths. In support of the first hypothesis, microcracking can increase the effective fatigue life of a cement stabilized layer by changing the condition of the base from a few wide reflective drying shrinkage cracks to a layer with many narrow drying shrinkage cracks with stress concentrations that are too small to reflect through the surface layer. By reducing the widths of the wide cracks where failure is first expected, the expected effective fatigue life of the cement stabilized layer can also be increased through improved load transfer efficiency (LTE) and aggregate interlock to reduce the stresses and strains adjacent to the cracks at the bottom of the cement stabilized layer. The interior of the slab where no cracks are present, will have the longest fatigue life, but this is not the critical area where the pavement fails . The hypothesis that microcracking mitigates drying shrinkage cracks by creating a network of hairline cracks to relieve stresses that would otherwise create a few wide cracks was amended during the course of this research. Field observations and microcracking simulations have shown that microcracking reduces the strength and effective layer thickness, leading to the development of additional shrinkage cracks and resulting in overall reduced crack widths. The influence of mix design on the stiffness of FDR-PC with microcracking was also investigated to evaluate the second hypothesis. The FDR-PC with microcracking recovered to stiffness levels greater than that of the unmicrocracked field and laboratory experiments in the lower strength mix design. The increased stiffness recovery observed after microcracking was attributed to secondary cementation as free water is mobilized through the induced microcracks to promote recementation and to hydrate previously unhydrated cement. The research has shown that increasing the water to cement for cementation ratio (w/cc), by reducing the cement content, can improve the ability of the FDR-PC to recover stiffness after microcracking. The initial consumption of stabilizer (ICS) test was considered to determine the minimum cement content to ensure durability. By using the minimum required cement content that satisfies both the strength and durability requirements, the long-term stiffness levels of the FDR-PC exceeded the stiffness levels without microcracking. This provides a two-fold benefit of reduced crack widths due to the lower strength of the material, and increased stiffness, and thus fatigue life, for the same material. This supported the second hypothesis for this research. Microcracking is a shrinkage crack control method that can mitigate large shrinkage cracks, but it needs to be considered together with the mix design to maximize the benefits microcracking can provide. The recommended microcracking effort to maximize long term stiffness and minimize crack widths developed from the results of this study is: during the period from 48 to 56 hours after compaction, microcrack the surface by applying a load per width of roller of 2.8 to 4.3 kN/cm using a 10- to 12-ton vibratory steel drum roller at maximum vibration amplitude travelling from 3 to 4.5 km/hr (2 to 3 mph). The study also recommended using the maximum of either the cement content that satisfies both the minimum seven-day design strength and the ICS plus 1 percent cement content. This research contributes extensive knowledge to the current understanding of cement stabilized layers. Cement stabilized layers still crack with microcracking, but through improved mix designs, pavement design, construction and microcracking, cement stabilized layers can last longer, and deteriorate more uniformly.
Author: Imad L. Al-Qadi
Publisher: CRC Press
ISBN: 0203882199
Category : Technology & Engineering
Languages : en
Pages : 932
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Book Description
Internationally, much attention is given to causes, prevention, and rehabilitation of cracking in concrete, flexible, and composite pavements. The Sixth RILEMInternational Conference on Cracking in Pavements (Chicago, June 16-18, 2008) provided a forum for discussion of recent developments and research results.This book is a collection of papers fr
Author: Haifang Wen
Publisher:
ISBN: 9780309308137
Category : Pavements
Languages : en
Pages : 72
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Book Description
"TRB's National Cooperative Highway Research Program (NCHRP) Report 789: Characterization of Cementitiously Stabilized Layers for Use in Pavement Design and Analysis presents performance-related procedures for characterizing cementitiously stabilized layers for incorporation into mechanistic-empirical pavement analysis methods. Appendices to the report are available online."--Publisher's description.
Author: Pranshoo Solanki
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 634
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Author:
Publisher:
ISBN:
Category : Electronic book
Languages : en
Pages :
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Author: Sarah Springman
Publisher: CRC Press
ISBN: 0415592887
Category : Technology & Engineering
Languages : en
Pages : 1530
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Book Description
This book results from the 7th ICPMG meeting in Zurich 2010 and covers a broad range of aspects of physical modelling in geotechnics, linking across to other modelling techniques to consider the entire spectrum required in providing innovative geotechnical engineering solutions. Topics presented at the conference: Soil – Structure – Interaction; Natural Hazards; Earthquake Engineering: Soft Soil Engineering; New Geotechnical Physical; Modelling Facilities; Advanced Experimental Techniques; Comparisons between Physical and Numerical Modelling Specific Topics: Offshore Engineering; Ground Improvement and Foundations; Tunnelling, Excavations and Retaining Structures; Dams and slopes; Process Modelling; Goenvironmental Modelling; Education
Author: Eyad Masad
Publisher: CRC Press
ISBN: 042985580X
Category : Technology & Engineering
Languages : en
Pages : 596
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Book Description
Advances in Materials and Pavement Performance Prediction contains the papers presented at the International Conference on Advances in Materials and Pavement Performance Prediction (AM3P, Doha, Qatar, 16- 18 April 2018). There has been an increasing emphasis internationally in the design and construction of sustainable pavement systems. Advances in Materials and Pavement Prediction reflects this development highlighting various approaches to predict pavement performance. The contributions discuss links and interactions between material characterization methods, empirical predictions, mechanistic modeling, and statistically-sound calibration and validation methods. There is also emphasis on comparisons between modeling results and observed performance. The topics of the book include (but are not limited to): • Experimental laboratory material characterization • Field measurements and in situ material characterization • Constitutive modeling and simulation • Innovative pavement materials and interface systems • Non-destructive measurement techniques • Surface characterization, tire-surface interaction, pavement noise • Pavement rehabilitation • Case studies Advances in Materials and Pavement Performance Prediction will be of interest to academics and engineers involved in pavement engineering.
Author: Inge Hoff
Publisher: CRC Press
ISBN: 1000533336
Category : Technology & Engineering
Languages : en
Pages : 501
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Book Description
Innovations in Road, Railway and Airfield Bearing Capacity – Volume 1 comprises the first part of contributions to the 11th International Conference on Bearing Capacity of Roads, Railways and Airfields (2022). In anticipation of the event, it unveils state-of-the-art information and research on the latest policies, traffic loading measurements, in-situ measurements and condition surveys, functional testing, deflection measurement evaluation, structural performance prediction for pavements and tracks, new construction and rehabilitation design systems, frost affected areas, drainage and environmental effects, reinforcement, traditional and recycled materials, full scale testing and on case histories of road, railways and airfields. This edited work is intended for a global audience of road, railway and airfield engineers, researchers and consultants, as well as building and maintenance companies looking to further upgrade their practices in the field.
Author: Rong Luo
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 254
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Book Description
The State of Texas has the most extensive network of surface-treated pavements in the nation. This network has suffered from the detrimental effects of expansive soils in the subgrade for decades. Longitudinal cracking on the Farm-to-Market (FM) network is one of the most prevalent pavement distresses caused by volumetric changes of expansive subgrades. Engineering practice has shown that geogrid reinforcement and lime treatment can effectively reduce the reflection of longitudinal cracking on the pavement over shrinking subgrade. However, little is known about the mechanism leading to the propagation of the shrinkage cracks to the surface of the pavement. The use of geogrid reinforcement and lime treatment is mostly based on empirical engineering experience and has not been addressed in depth. This dissertation research evaluates the stress field and constitutive models of the subgrade soil subjected to matric suction change. The non-uniform matric suction change in the subgrade is simulated by a thermal expansion model in a finite element program, ABAQUS, to determine the shrinkage stresses in the subgrade soil and pavement structure. Numerical solution by the finite element analysis shows that the most likely location of shrinkage crack initiation in the subgrade is close to the pavement shoulder and close to the interface of the base and subgrade. Linear elastic fracture mechanics theory is used to analyze the crack propagation in the pavement. Compared to the fracture toughness of the pavement materials, the stress concentration at the initial shrinkage crack tip is large enough to drive the crack to propagate further. When the shrinkage crack propagates through the whole pavement structure, a longitudinal crack develops at the pavement surface close to the pavement shoulder. Based on the analysis of shrinkage crack propagation, this dissertation investigates the mechanism of geogrid reinforcement and lime treatment. The geogrid can significantly reduce the stress concentration at the crack tip if the geogrid is placed at the bottom of the base. A geogrid with a higher stiffness further reduces the stress intensity factor at the upper tip of the shrinkage crack. The lime treatment can improve the mechanical properties of the expansive soil in several ways. The lime-treated soil has lower plasticity index, higher tensile strength and higher fracture toughness. The possible location of the shrinkage crack initiation is not in the lime-stabilized soil but in the untreated natural soil close to the bottom of the lime-treated layer, where tensile stresses exceed the tensile strength of the untreated soil. The shrinkage crack is less likely to develop through lime-treated soil, which has increased fracture toughness. The combination of geogrid reinforcement and lime treatment offers the most benefit for the control of dry-land longitudinal cracking. In a pavement with a lime-treated layer, the best place to install the geogrid is at the interface between the lime-stabilized layer and the untreated natural soil. If using a geogrid with high stiffness, the Mode I stress intensity factor may be reduced to a certain level that is lower than the fracture toughness of the pavement material.
