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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 13 Abstracts search results
Document:
SP141-05
Date:
December 1, 1993
Author(s):
Rachel J. Detwiler and John A. Bickley
Publication:
Symposium Papers
Volume:
141
Abstract:
For some years, the Ministry of Transportation of Ontario (MTO) and the Ready-Mixed Concrete Association of Ontario (RMCAO) have separately run programs to measure the reproducibility of test results between commercial laboratories. The comparative test results were made on standard cured 150 mm diameter by 300-mm test cylinders. The reproducibility of test results obtained between testing laboratories on nominally identical test specimens is an important factor in the statistical evaluation of test data. Unless the reproducibility is good, concrete mixes need to be overdesigned, with resulting higher costs. In addition, poor reproducibility between laboratories increases the probability that some test cylinders will fail to meet specified strength requirements. Even if the concrete in the structure represented by these results probes to be adequately strong, disruption and economic loss result from the publication of erroneous results. This paper analyzes the data obtained by the RMCAO, derives repeatability and reproducibility indexes, and discusses their economic consequences. Some data from the MTO program are also reported. Recommendations for improvements are made.
DOI:
10.14359/3991
SP141
Editors: Tony C. Liu and George C. Hoff / Sponsored by: ACI Committee 214
This Special Publication of 12 papers contains a wide range of subjects related to concrete materials and technology. Topics include statistical methods for evaluations of core strength and in-place concrete test results, roller compacted concrete dams, concrete bridge pavements, reliability of models for precast concrete slabs, quality assurance and quality control, plus numerous other topics. Note: The individual papers are also available as .pdf downloads.. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP141
10.14359/14181
SP141-03
Nicholas J. Carino
In-place testing is used to estimate the compressive strength of concrete in a structure by measuring another related property. A strength relationship is used to convert the in-place test results to an estimate of the compressive strength. Statistical methods are needed for reliable estimates of in-place strength. Such methods should account for the uncertainties in the measured property, the uncertainty of the strength relationship, and the variability of the in-place concrete. Standard statistical procedures for dealing with these uncertainties have not yet been adopted in North American practice. Recommendations are provided for developing the strength relationship, and a reliable, easy-to-use approach is presented to estimate in-place characteristic strength.
10.14359/3989
SP141-06
William F. Kepler
The Bureau of Reclamation has produced mass concrete since 1904. Since then, quality assurance of mass concrete has evolved from the rudimentary measurement of batch volumes to using computers to batch and evaluate concrete. The construction of Hoover Dam in 1931 was a major turning point in quality assurance of mass concrete, with the initiation of scientific evaluations of the physical properties of concrete and concrete-making materials. Reclamation's goal is to provide the most economical concrete mixture that will meet the design and construction requirements. Over the years, several effective procedures have been developed to meet that goal. The primary focus is to keep the amount of cementitious materials low. This is done in several ways. Large, nominal, maximum-sized aggregates are used, multiple coarse aggregates are blended to reduce the required mortar volume, and the fines content is kept very low. The next step is to use high quality materials. Reclamation's specifications for fly ash and aggregates are more stringent than the ASTM standards. To minimize overdesign, close control is maintained over the batching process, helping to keep a low standard deviation. Paper discusses the different methods the Bureau of Reclamation uses to produce economical, high-quality mass concrete mixtures.
10.14359/3992
SP141-07
Timothy P. Dolen and kurt F. Von Fay
The Bureau of Reclamation has proportioned roller compacted concrete (RCC) mixtures since 1979, beginning with the Upper Stillwater Dam Project. Reclamation's research and project-related RCC investigations cover a variety of structures and varying site conditions. Reclamation proportions RCC mixtures to meet both fresh and hardened concrete properties. This assures construction of high-quality concrete structures. Ongoing research has continued to identify specific properties of RCC, such as bond strength, freeze-thaw durability, and thermal properties that significantly affect the performance of these structures. Paper summarizes RCC mixture proportions and properties of fresh and hardened concrete from Reclamation's RCC research and project activities.
10.14359/3993
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