Evaluation of Consolidation Problems in Thicker Portland Cement Concrete Pavements PDF Download
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Author: Jennifer A. Distlehorst
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 53
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Book Description
The purpose of this study was to investigate methods of reducing the size and total volume of the entrapped air voids in concrete slabs that are over 9 in. thick. Laboratory and field tests were designed to investigate the effect of variations in vibration frequency and aggregate gradation on entrapped air content, strength and performance factors such as smoothness, faulting, adhesion failures, and spalling. In 1993, a test section was constructed to compare the effects of increasing the proportion of coarse aggregate to fine aggregate and increasing vibration frequency. Annual surveys of joint sealant failures, spalling and joint faulting were performed from 1994 to 2001 on this test section. Samples from this project were cut, polished and analyzed to determine entrained and entrapped air content. In 1994, another test section was constructed to assess the effect of controlling the total gradation of concrete aggregate and increasing vibration frequency. A profilograph test was performed in 1996 to measure pavement smoothness on this project. Core samples were taken from both the wheel path and the wheel gap and nuclear density meters were used on both projects to measure the in-situ density of the pavements.
Author: Jennifer A. Distlehorst
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 53
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Book Description
The purpose of this study was to investigate methods of reducing the size and total volume of the entrapped air voids in concrete slabs that are over 9 in. thick. Laboratory and field tests were designed to investigate the effect of variations in vibration frequency and aggregate gradation on entrapped air content, strength and performance factors such as smoothness, faulting, adhesion failures, and spalling. In 1993, a test section was constructed to compare the effects of increasing the proportion of coarse aggregate to fine aggregate and increasing vibration frequency. Annual surveys of joint sealant failures, spalling and joint faulting were performed from 1994 to 2001 on this test section. Samples from this project were cut, polished and analyzed to determine entrained and entrapped air content. In 1994, another test section was constructed to assess the effect of controlling the total gradation of concrete aggregate and increasing vibration frequency. A profilograph test was performed in 1996 to measure pavement smoothness on this project. Core samples were taken from both the wheel path and the wheel gap and nuclear density meters were used on both projects to measure the in-situ density of the pavements.
Author: Daniel Okpala
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 50
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Book Description
Author: Ernest Zube
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages :
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Author: Daniel Stephen Lane
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 18
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Book Description
Petrographic examinations of specimens from two recently constructed concrete pavements suggested that complete consolidation of the concrete may not have been achieved. Consequently, a quantitative evaluation of the degree of consolidation in these specimens was undertaken. The pavements were of plain, jointed design with dowels for load transfer. Both projects were constructed using slip-form paving machines with spud vibrators. It was found that the entrapped void content was excessive. In both cases, the entrapped void content of the lower half of the pavement was higher than the upper half. This situation apparently occurred because the vibrators were set to ride above the preplaced dowel assemblages. In one pavement the consolidation of the upper half was adequate, but the entrapped void content of the upper half of the other pavement was also found to be excessive. The following recommendations are made: (1) During preplacement conferences and actual construction, emphasize the importance of adequate consolidation of concrete throughout the pavement, especially in the vicinity of dowel assemblages. (2) Consider alternative methods of dowel placement. Pavers with dowel bar inserters are available. (3) Investigate methods to evaluate and monitor consolidation during construction. Nuclear gauges are used for this purpose in some states although not all applications have been successful. Ultrasonic techniques show promise for this application.
Author: David Whiting
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 152
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Book Description
A study was made of the influence of consolidation on properties of portland cement concrete. A model acceptance sampling plan for concrete consolidation is proposed. The plan is of the inspection by variables type and requires a sample size of eight per lot. The plan provides for buyer's and seller's risks of 5 percent. The plan was field tested in Idaho and Iowa. Field testing indicated that monitoring concrete pavement consolidation is practical and economically feasible.
Author:
Publisher:
ISBN:
Category : Concrete
Languages : en
Pages : 230
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Book Description
This study evaluated the impacts of construction on the air content and air-void system structure of Portland cement concrete pavements. The primary intent was to quantify the air content of fresh concrete before and after it has gone through the slipform paver. The air-void system parameters of hardened concrete were then assessed using cast and extracted core specimens. The results of the air content testing on fresh concrete and the concrete cylinder specimens cast in the field suggested that there is some loss of air as the concrete passes through the paver. Laboratory testing performed on cores extracted from the pavement did not provide any conclusive evidence that entrained air is lost during the slipform paving process. In fact, many of the extracted cores had measured air content values that were much higher than the specification requirement. If excessive, this could result in increased permeability and low-strength related issues. Although a rigorous statistical analysis was not performed, the results suggest that the air content testing on fresh concrete is not capturing the true air content of the concrete placed with a slipform paver. The fresh concrete air content is generally lower than the air content measured in the cores.
Author: Denis E. Donnelly
Publisher:
ISBN:
Category : Pavements, Concrete
Languages : en
Pages : 36
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Book Description
Author:
Publisher:
ISBN:
Category : Technology & Engineering
Languages : en
Pages : 92
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Book Description
Author: Allen L. Cooley
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 106
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Book Description
Based upon the work conducted in this study, it was concluded the recycled portland cement concrete pavements are available as an option for the construction of gravel cushion and aggregate base course layers.
Author: James A. Crovetti
Publisher:
ISBN:
Category : Pavements
Languages : en
Pages : 82
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Book Description
