Download or read book ACI PRC 214 4 21 Obtaining Cores and Interpreting Core Compressive Strength Results Guide written by ACI Committee 214 and published by . This book was released on 2021-05-31 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Guide for Obtaining Cores and Interpreting Compressive Strength Results written by ACI Committee 214 and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This guide summarizes current practices for obtaining cores and interpreting core compressive strength test results. Factors that affect the in-place concrete strength are reviewed so locations for sampling can be selected that are consistent with the objectives of the investigation.
Download or read book Guide for Obtaining Cores and Interpreting Compressive Strength Results written by American Concrete Institute and published by . This book was released on 2010 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 214 4R 03 written by ACI Committee 214 and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Report on High Strength Concrete written by ACI Innovation Task Group 4 and published by . This book was released on 2010 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: "This guide summarizes current practices for obtaining cores and interpreting core compressive strength test results. Factors that affect the in-place concrete strength are reviewed so sampling that are consistent with the objectives of the investigation can be selected"--P. 1.
Download or read book Investigation of Parameters Effecting Concrete Core Performance for Quality Control and Assurance written by Marc Johnson and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The ever-evolving concrete construction industry has required stronger concrete, faster turnarounds, and better durability. To achieve this, the concrete mixtures have changed drastically, including a large amount of cementitious materials, lower amount of water relative to the amount of cementitious materials, supplementary cementitious materials, and chemical admixtures. Each of these changes alters the properties and the behaviour of both fresh and hardened concrete. The standards and codes relating to the quality control and assurance of concrete structures were based on research conducted decades ago, which utilized on concrete mixtures which contained none of these changes and would not meet the expectations of modern concrete construction. The parameters of core testing, time, location, and direction of core extraction, the condition of the core between extraction and testing, the diameter, and the length-to-diameter (l/d) ratio of the core, all have effects on the results of the compressive strength test. Due to the property changes caused by the modern concrete mixtures, the effect that these parameters had on the result of the compressive strength test may or may not be true nowadays. At the request of the Ministry of Transportation of Ontario, an experimental project was conducted to determine the effects that various parameters have on the day 28 compressive strength of concrete samples, and which combination of these parameters would be optimal for quality assurance testing purposes. In total, 8 sets of concrete structures were created and tested, totaling 884 concrete samples, of which 713 underwent compression testing. These sets of concrete samples included beams, wall sections to represent girder webs, large box structures, manhole risers, and standard concrete cylinders which were constructed in the University of Waterloo laboratory and in pre-cast manufacturer facilities. Other tests were conducted, including the bulk resistivity, rapid chloride permeability, and air void systems. These tests are not discussed in this thesis but were discussed elsewhere [1]. The purpose of this project was to determine how different core parameters affected the compressive strength results, and how modern concrete mixtures adhere to the current practices outlined in standards and codes. These parameters are the time of coring (day 3, 7, 14, and 28), location of the core along the length and height of a structure, direction of core extraction (perpendicular or parallel to the direction of casting), the condition of the core between extraction and testing (sealed in plastic or soaked in a saturated calcium hydroxide solution), the diameter of the core (75 mm or 100 mm), and the core l/d ratio (2 or 1.5). A statistical analysis was carried out at a 95% confidence level to determine these effects. Each sample set varied a parameter to isolate its effect on the compressive strength. Once isolated, the effect of the parameters was determined through statistical comparisons. The time of coring was found to have no significant effect on the day 28 compressive strength, regardless of how the core was conditioned between the coring and testing day. The height and length along a structure was also found to be insignificant, provided the concrete mixture included supplementary cementitious materials (SCMs) which reduce the bleed water. A similar conclusion was found for the direction of coring: provided the concrete mixture includes SCMs which reduce bleed water, there was no significant difference between the two directions of coring: perpendicular and parallel to the casting direction. However, the condition in which the core is stored between coring and testing was found to be significant. The cores which were soaked had a 2.3% lower compressive strength than cores sealed in plastic, as recommended by ASTM C42 [2]. The soaked cores were also half as variable with a coefficient of variation (CoV) of 4.73% compared to 9.31% for the sealed cores. The strength correction factor (SCF) in ACI 214 [3] of 0.917 for equating a sealed core compressive strength to a soaked core was found to be inadequate for the data presented, which found 0.977 to be adequate. Similar for the diameter of the samples: 75 mm diameter samples were found to have a 1.5% higher and 25% more variable compressive strength than 100 mm diameter samples. The SCF found in ACI 214 [3] was found to be adequate for the data presented. Lastly, the l/d ratio models presented in CSA A23.1 [4], ASTM C42/C39 [2, 5], and ACI 214 [3] were found to not adequately represent the data in this project. Instead, a modified version of the ACI 214 model was suggested; however, this model was sensitive to the input data. Another suggestion is to calculate a SCF for each unique concrete mixture and structure type by averaging the compressive strengths of samples with the standard l/d ratio of 2 to the compressive strengths of samples with a non-standard l/d ratio (i.e. F_(l⁄d)=f_(c,l⁄d=2)⁄f_(c,l⁄d≠2) ). This second method provided SCFs on par with the modified ACI 214 model, while compensating for sensitivity in the concrete mixtures and construction techniques. Once all the effects of the parameters discussed above are combined, the variability of 100 mm diameter samples with an l/d ratio of 1.5 was found to be less than the variability of 75 mm diameter samples with an l/d ratio of 2. To ensure equivalent variability in sets of samples, additional cores should be extracted, depending on the CoV of the sample data and the non-standard parameters. For example, with a CoV of 6.1%, four saturated cores with a 100 mm diameter and an l/d ratio of 1.5 or five saturated cores with a 75 mm diameter and an l/d ratio of 2 would be required to be equivalent to three standard cores. To ensure the same probability of passing quality assurance testing, where the average compressive strength of three cores must be at least 0.85f_c^' with no single value below 0.75f_c^' [3, 4], the limits may be changed to accommodate the increased variability associated with non-standard parameters on the core. For instance, with a CoV of 6.1%, five 75 mm diameter cores with an l/d ratio of 2 having no single value below 0.66f_c^' would be equivalent to the current three 100 mm diameter cores with an l/d ratio of 2 having no single value below 0.75f_c^'. All of findings above lead to the conclusions that concrete samples from modern concrete mixtures, which include high cementitious contents, low water to cementitious materials ratio, SCMs, and chemical admixtures, are not represented adequately by the current codes and standards.
Download or read book Guide to Evaluation of Strength Test Results of Concrete written by ACI Committee 214 and published by . This book was released on 2011-04 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recommended Practice for Evaluation of Strength Test Results of Concrete ACI 214 77 written by ACI Committee 214 and published by . This book was released on 1976 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Recommended Practice for Evaluation of Strength Test Results of Concrete written by American Concrete Institute. Committe 214 (ACI) and published by . This book was released on with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simplified Version of the Recommended Practice for Evaluation of Strength Test Results written by ACI Committee 214 and published by . This book was released on 1988 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book In place Methods to Estimate Concrete Strength written by ACI Committee 228--Nondestructive Testing of Concrete and published by . This book was released on 1995 with total page 41 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ACI 440 2R 17 Guide for the Design and Construction of Externally Bonded FRP Systems for Strengthening Concrete Structures written by ACI Committee 440 and published by . This book was released on 2017-04-27 with total page 110 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Regions and Powers written by Barry Buzan and published by Cambridge University Press. This book was released on 2003-12-04 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book develops the idea that since decolonisation, regional patterns of security have become more prominent in international politics. The authors combine an operational theory of regional security with an empirical application across the whole of the international system. Individual chapters cover Africa, the Balkans, CIS Europe, East Asia, EU Europe, the Middle East, North America, South America, and South Asia. The main focus is on the post-Cold War period, but the history of each regional security complex is traced back to its beginnings. By relating the regional dynamics of security to current debates about the global power structure, the authors unfold a distinctive interpretation of post-Cold War international security, avoiding both the extreme oversimplifications of the unipolar view, and the extreme deterritorialisations of many globalist visions of a new world disorder. Their framework brings out the radical diversity of security dynamics in different parts of the world.
Download or read book LRFD Guide Specifications for the Design of Pedestrian Bridges written by American Association of State Highway and Transportation Officials and published by AASHTO. This book was released on 2009 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Building Code Requirements for Structural Concrete ACI 318 05 and Commentary ACI 318R 05 written by ACI Committee 318 and published by American Concrete Institute. This book was released on 2005 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Capital Preventive Maintenance written by and published by . This book was released on 2004 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Structure and Conformation of Amphiphilic Membranes written by Reinhard Lipowsky and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 307 pages. Available in PDF, EPUB and Kindle. Book excerpt: Membranes composed of amphiphilic molecules are highly flexible surfaces that determine the architecture of biological systems and provide a basic structural element for complex fluids such as microemulsions. Recently, a variety of new experimental methods such as X-ray scattering, neutron scattering, and atomic force microscopy have been used in order to study themolecular structure of these membranes. Their conformational behavior, on the other hand, is studied by optical and electron microscopy, which reveals that membranes in aqueous solution exhibit an amazing variety of different shapes. Several theoretical concepts are described suchas bending elasticity, curvature, and minimal surfaces in order to understand this polymorphism. These concepts are also useful to describe the behavior of membranes in complex fluids where they can build up hexagonal, lamellar, triply-periodic, cubic, and sponge phases. The contributions to this volume provide an up-to-date overview and describe thestate-of-the-art of this rapidly evolving field of research.
