Repeatability of Workability Test Methods of Self-Consolidating Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1981-1986
Author(s):  
Wu Jian Long ◽  
Kamal Henri Khayat ◽  
Feng Xing
Keyword(s):  
Test Methods ◽  
Test Method ◽  
Upper And Lower Bounds ◽  
Test Results ◽  
Self Consolidating Concrete ◽  
Slump Flow ◽  
Single Operator ◽  
Crushed Aggregate ◽  
Relative Errors ◽  
Flow Consistency

In general, in the evaluation of a test method, the repeatability tests must be performed to establish upper and lower bounds for the precision of a test method. The repeatability is calculated as a standard deviation and relative error of test results. In order to evaluate the repeatability of the workability tests used in self-consolidating concrete (SCC) applications, an SCC mixture proportioned with 0.38 w/cm, Type MS cement, 480 kg/m3 of binder , and crushed aggregate with MSA of 12.5 mm was used. The dosage rate of the HRWRA of the SCC was adjusted to secure two initial slump flow consistency levels of 630 ± 10 mm and 700 ± 10 mm for the repeatability tests. For each consistency level, the concrete was batched five times (for a total of 10 mixtures). Each test was repeated five times by the same operator in order to establish the single-operator precision values. Furthermore, five different operators were used to perform each of the workability tests in order to assess the multi-operator error that could occur during testing. Based on the relative errors obtained in the repeatability tests, relatively low error values were obtained for the slump flow, J-Ring flow, and L-box blocking ratio tests. Relative errors for recommended SCC workability test methods were also summarized.

scholarly journals Correlations Among Various Self-Consolidating Concrete Workability Responses

2012 ◽  
Vol 6 (1) ◽  
pp. 38-47 ◽  
Author(s):  
Wu-Jian Long ◽  
Kamal Henri Khayat ◽  
Feng Xing
Keyword(s):  
Mechanical Vibration ◽  
Maximum Size ◽  
Test Methods ◽  
Test Results ◽  
Testing Methods ◽  
Self Consolidating Concrete ◽  
Filling Ability ◽  
Crushed Aggregate ◽  
Class F Fly Ash ◽  
Passing Ability

Self-consolidating concrete (SCC) mixtures designated for precast, prestressed applications should be highly workable to flow easily through restricted spacing and completely encapsulate reinforcements without any mechanical vibration. Key workability characteristics of SCC can be described in terms of filling ability, passing ability, and resistance to segregation. These properties are typically characterized by data that relate to specific testing methods. In general, these methods include the components required for evaluating simultaneously filling ability, passing ability, and resistance to segregation, since these properties are rather interrelated. In this investigation, 33 SCC mixtures made with various mixture proportioning parameters, including maximum size and type of aggregate, type and content of binder, and w/cm were evaluated. The mixtures were prepared using crushed aggregate and gravel of three different nominal sizes, w/cm of 0.33 and 0.38, and three binder compositions: Type MS cement, Type HE cement with 30% of slag replacement, and Type HE cement with 20% of Class F fly ash. Comparisons and correlations among various test results used in evaluating the workability responses obtained for these mixtures are established. This is done to highlight advantages and limitations of the various test methods that can be used to assess workability of SCC designated for prestressed applications. Appropriate combinations of test methods that can be used to assess workability of SCC at the precast plant are recommended, and ranges of acceptance of the various test methods are established.

Experimental Research on Vibration Characteristics of Laminated Composite Cantilever Beam

2021 ◽  
Author(s):  
Rui Yang ◽  
Xiaobin Li ◽  
Hongxi Li
Keyword(s):  
Cantilever Beam ◽  
Optical Measurement ◽  
Laminated Composite ◽  
Experimental Methods ◽  
Test Methods ◽  
Vibration Characteristics ◽  
Test Method ◽  
Vibration Measurement ◽  
Vibration Test ◽  
Test Results

Abstract In this paper, the vibration characteristics of laminated composite cantilever beam is taken as the research object. Firstly, a vibration formula specific for laminated composite cantilever beam is derived, from which the low order natural frequency of laminated composite cantilever beam is calculated; Secondly, two experimental methods, electrical and optical measurement, are used to study the vibration characteristics of laminated composite cantilever beam, and the influence of different test methods, sensor types, number of measuring points and excitation methods on the test results are analyzed. Through the combination of theory and experiment, a test method that can be applied to the vibration test of composite material laminated structure cantilever beam is obtained. Based on the laser vibration measurement method in the optical method, the results show that the deviation between the experimental data and the theoretical solution is the smallest when the distance between the probe and the specimen is 0.5m and the sampling time is 5s by using the optical fiber vibrometer. The research content of this article can provide a reasonable reference for related vibration test research.

Methods to Evaluate Cleaners and Sanitizers

1982 ◽  
Vol 45 (13) ◽  
pp. 1257-1260 ◽  
Author(s):  
DALE L. SCHEUSNER
Keyword(s):  
Test Methods ◽  
Test Method ◽  
Test Results ◽  
Standard Laboratory ◽  
Test Procedures ◽  
Laboratory Methods ◽  
Product Use ◽  
Cellulose Sponge ◽  
Equivalent Test ◽  
Recovery Methods

Methods to evaluate germicides can be grouped into three categories: standard laboratory tests, in-use tests and simulated-use tests. Standard laboratory methods, such as the Available Chlorine Germicidal Equivalent test, are specifically defined for reproducibility in any laboratory by any operator, but the test results often lack relevance to actual product-use conditions. In-use test methods are relevant to product-use; however, in-use test procedures do not permit proper controls to be included in the organism recovery methods. Contact plates give an estimate of organism numbers which is only 25% of the theoretical number of organisms present. Organism recovery using a swab, cellulose sponge or tube sampler give estimates of organisms ranging from 91 to 111% of theoretical. The tube sampler is a 1-in. length of flexible tubing having a 1-in. interior diameter and a smooth end, which can make a water-tight seal on a flat surface. Simulated use testing yields data which are relevant to actual product-use. A cafeteria tray is soiled, inoculated and cleaned in a manner to simulate actual product-use. This test method permits the necessary controls to be used. Tray-test reproducibility is as good as that of the other recovery methods tested and organism recovery is quantitative. The tray test provides a means for determining biological cleaning where the effect of both cleaning and germicidal activity are measured together.

scholarly journals Evaluation of Self-Consolidating Concrete Robustness by Measuring Electrical Conductivity of Plastic Concrete

2018 ◽  
Author(s):  
Payam Vosoughi ◽  
Mahmoud Motahari Karein
Keyword(s):  
Electrical Conductivity ◽  
Setting Time ◽  
Test Methods ◽  
Test Method ◽  
Fresh Properties ◽  
Conventional Concrete ◽  
Self Consolidating Concrete ◽  
Plastic Concrete ◽  
Cement Based Materials ◽  
Long Time

This paper is aimed to review robustness of Self-Consolidating Concrete (SCC) in term of resistance against static segregation and bleeding. SCC is a highly fluid and non-segregating concrete able to spread through even dense reinforcement and homogenously fill formwork without using any external mechanical consolidation. Due to field requirements, SCC should be able to sustain its desired fresh properties over a relatively long time (about two or three hours) making it more susceptible to segregation than conventional concrete. Although there are a coupleof proposed test methods to evaluate SCC robustness, multi-electrodes electrical conductivity technique could be a reliable, non-destructive, inexpensive and simple test method to continuously monitor progress of hydration reactions (even indicating initial and final setting time) and stability (bleeding and both static and dynamic aggregate segregation) of plastic cement-based materials over the early-age period. In this paper, a brief review on fresh properties of SCC and staticaggregate segregation has been taken place. Then, different methods for measuring concrete conductivity have been investigated. Afterward, some studies on evaluation of stability of cement-based materials and SCC have been reviewed. Finally, based on the literature, some recommendations for future works are introduced.

scholarly journals Performance characteristics of polymerase chain reaction and histological methods for the detection of Haplosporidium nelsoni in the eastern oyster (Crassostrea virginica)

2015 ◽  
Vol 27 (4) ◽  
pp. 476-488 ◽  
Author(s):  
Nellie Gagné ◽  
Anne Veniot ◽  
Mary Stephenson ◽  
Carol McClure
Keyword(s):  
Polymerase Chain Reaction ◽  
Test Methods ◽  
Test Method ◽  
Performance Characteristics ◽  
Analytical Sensitivity ◽  
Test Results ◽  
Fitness For Purpose ◽  
Chain Reaction ◽  
Repeatability And Reproducibility ◽  
Polymerase Chain

Fitness for purpose and validation are increasingly becoming a benchmark in the development of test methods for the diagnosis of infectious diseases in aquatic animals. The design of the evaluation and the analysis of data are critical to demonstrate test method performance characteristics and fitness for purpose, as stated in the World Organization for Animal Health pathway for test validation. Three test methods for the detection of the oyster parasite Haplosporidium nelsoni were selected for the validation study described herein: histology, end-point polymerase chain reaction (PCR), and real-time PCR (qPCR). Preliminary work evaluated the analytical sensitivity and specificity of the PCR and qPCR assay in development. The following stage used test results on 100 oysters in 3 different laboratories to assess diagnostic sensitivity (DSe), diagnostic specificity (DSp), repeatability, and reproducibility. Repeatability and reproducibility were within 68–95%. The final part of the project evaluated DSe and DSp using test results on 400 oysters and results from the first 100 oysters tested. In the absence of a 100% gold standard test, latent class modeling methods were explored to characterize the tests (i.e., Bayesian analyses). For both PCR methods, DSe was >90%, and in the 60% range for histology, whereas DSp was >90% for all methods. Based on the results of this validation, a threshold cycle value of 30 for qPCR corresponds to the limit of sensitivity for histology where unreliable detection becomes more frequent, thus providing a threshold helpful in diagnostic settings where both histology and qPCR are used.

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