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Book Investigation of Low Compressive Strengths of Concrete in Paving Precast and Structural Concrete Study

Download or read book Investigation of Low Compressive Strengths of Concrete in Paving Precast and Structural Concrete Study written by and published by . This book was released on 2000 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research examines the causes for a high incidence of catastrophically low compressive strengths, primarily on structural concrete, during the 1997 construction season. The source for the low strengths was poor aggregate/paste bond associated with air void clusters and poorly formed cement paste in the interfacial region adjacent to the aggregate. An interaction between the 3synthetic4 air entraining admixtures, used as substitutes for vinsol resin, and low alkali cements was directly tied the problem with high summertime temperatures also contributing to the problem. The 3synthetics4 appear to be more hydrophobic, form thinner-walled air bubbles and develop rapid draining bubble flocculations more readily than vinsol resin, all of which can lead to significant reductions in strength. As an interim measure, the Department specified the sole use of vinsol resin air entraining agents along with water reducers, as needed, in April, 1998 and these measures have minimized the incidence of low strengths. Petrographic analysis of cores taken from low strength concretes failed to reveal the causes of the low strength problem but SEM microscopy clearly showed the failure mechanism. Laboratory testing of concrete mixes with various air entraining admixtures demonstrated an interaction was taking place with one cement and petrographic and chemical analysis of the cements used in the testing implicated alkali sulfates as a potential source of the interaction. Testing of the 3synthetic4 air entraining admixtures showed they have substantially different properties compared to vinsol resins. Mixtures of the 3synthetics4 and vinsol resin with 50 % or more vinsol resin behaved similarly to vinsol alone.

Book Field Study of Air Content Stability in the Slipform Paving Process

Download or read book Field Study of Air Content Stability in the Slipform Paving Process written by and published by . This book was released on 2012 with total page 230 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Book Investigation of the Suitability of Prepakt Concrete for Mass and Reinforced Concrete Structures

Download or read book Investigation of the Suitability of Prepakt Concrete for Mass and Reinforced Concrete Structures written by Waterways Experiment Station (U.S.) and published by . This book was released on 1951 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Material and Construction Optimization for Prevention of Premature Pavement Distress in PCC Pavements

Download or read book Material and Construction Optimization for Prevention of Premature Pavement Distress in PCC Pavements written by and published by . This book was released on 2008 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Phase I, the research team contacted each of 16 participating states to gather information about concrete and concrete material tests. A preliminary suite of tests to ensure long-term pavement performance was developed. The tests were selected to provide useful and easy-to-interpret results that can be performed reasonably and routinely in terms of time, expertise, training, and cost. The tests examine concrete pavement properties in five focal areas critical to the long life and durability of concrete pavements: (1) workability, (2) strength development, (3) air system, (4) permeability, and (5) shrinkage. The tests were relevant at three stages in the concrete paving process: mix design, preconstruction verification, and construction quality control. In Phase II, the research team conducted field testing in each participating state to evaluate the preliminary suite of tests and demonstrate the testing technologies and procedures using local materials.

Book Report of Investigations

Download or read book Report of Investigations written by and published by . This book was released on 1985 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Proceedings of the Fifth International Conference of Transportation Research Group of India

Download or read book Proceedings of the Fifth International Conference of Transportation Research Group of India written by Dharamveer Singh and published by Springer Nature. This book was released on 2022-05-13 with total page 523 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book (in three volumes) comprises the proceedings of the Fifth Conference of Transportation Research Group of India (CTRG2019) focusing on emerging opportunities and challenges in the field of transportation of people and freight. The contents of the book include characterization of conventional and innovative pavement materials, operational effects of road geometry, user impact of multimodal transport projects, spatial analysis of travel patterns, socio-economic impacts of transport projects, analysis of transportation policy and planning for safety and security, technology-enabled models of mobility services, etc. This book will be beneficial to researchers, educators, practitioners and policymakers alike.

Book Compressive Strength Testing of Concrete Paving Units

Download or read book Compressive Strength Testing of Concrete Paving Units written by Craig Walloch and published by . This book was released on 2014 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concrete paving units are governed by ASTM C936/C936M, Standard Specification Solid Interlocking Concrete Paving Units. Regardless of size or configuration, these units are required to have a minimum average compressive strength of 55 MPa (8000 psi). This strength was originally established when ASTM C936 was first approved in 1982 based on concrete paving units having a thickness of 60 mm (2.36 in.) and a thickness/width aspect ratio of approximately 0.6. Prior to August 2012, the compressive strength testing procedures in ASTM C140, Standard Test Methods for Sampling and Testing Concrete Masonry Units and Related Units, did not include consideration for the configuration of the tested specimen. This produced results that could vary solely due to specimen configuration. Because of the proliferation of shapes and sizes of manufactured concrete paving units in recent years, research was conducted to determine the effect of specimen configuration on compressive strength. The research indicates that the aspect ratio of tested specimens affects the measured strength. The results were used to support revisions to the testing procedures to standardize the compressive strength specimen configuration and institute an "aspect ratio factor" used in calculating compressive strength. A separate research project evaluated the effect of variables in capping of compression test specimens. Capping is essential for providing consistent bearing surfaces for strength testing; however, the type of material and the thickness of the cap were found to have significant effects on strength. The results were used to justify limiting the capping material for pavers to high-strength gypsum, and limiting the cap thickness to 1.5 mm (0.06 in.). This paper reviews both projects and the changes to ASTM C140 based on the results. In addition, this paper presents a useful guide for testing laboratories so that they can readily understand and comply with the new compressive strength testing requirements.

Book Correlation Between Tensile and Compressive Strengths for Lean Mass Concrete

Download or read book Correlation Between Tensile and Compressive Strengths for Lean Mass Concrete written by William O. Tynes and published by . This book was released on 1974 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Supplementary Cementitious Materials in Concrete

Download or read book Supplementary Cementitious Materials in Concrete written by and published by . This book was released on 2021-08-19 with total page 394 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Interrelations Between Cement and Concrete Properties

Download or read book Interrelations Between Cement and Concrete Properties written by Raymond Leonard Blaine and published by . This book was released on 1968 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: