Methods of test for hydraulic setting floor smoothing and/or levelling compounds. Determination of setting time

2002 ◽  
Keyword(s):  
Setting Time

scholarly journals Laser System for Testing Early Shrinkage of Concrete Elements in Conjuction with the Deterioration of the Setting Time

2016 ◽  
Vol 16 (2) ◽  
pp. 25-34
Author(s):  
Jacek Gołaszewski ◽  
Tomasz Ponikiewski ◽  
Grzegorz Cygan ◽  
Małgorzata Gołaszewska
Keyword(s):  
Concrete Beams ◽  
Setting Time ◽  
Laser System ◽  
Scratch Resistance ◽  
Sound Waves ◽  
Concrete Elements ◽  
Speed Propagation

Abstract The paper presents a method for testing the shrinkage of concrete beams with dimensions of 10x10x50cm. Measurements followed from setting into the form until 24 hours after setting. It was used modified TLS system, which originally was meant for the determination of changes in the length of thin-mortar. Simultanously measured were the changes of speed propagation of sound waves by Vikasonic, what allows to specify the setting time of binders. It could be a base for determining the scratch resistance of the concrete in the first 24 hours after casting.

Characterization of Canadian fly ashes and their relative performance in concrete

1987 ◽  
Vol 14 (5) ◽  
pp. 667-682 ◽  
Author(s):  
G. G. Carette ◽  
V. M. Malhotra
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Air Entrainment ◽  
Relative Performance ◽  
Hardened Concrete ◽  
Freezing And Thawing ◽  
Fly Ashes ◽  
Wide Range ◽  
Pozzolanic Properties

Eleven Canadian fly ashes were characterized and evaluated for their relative performance in concrete. Characterization included the determination of mineralogical composition, chemical composition, physical characteristics, and pozzolanic properties. The relative performance of each fly ash in concrete was evaluated through determination of the following properties of fresh and hardened concrete: slump, air content, bleeding, setting time, strength, modulus of elasticity, drying shrinkage, creep, and freezing-and-thawing resistance.The results indicate a wide range of chemical, physical, and pozzolanic properties for the fly ashes investigated. In spite of this, all the fly ashes studied are shown to be suitable for use in concrete. They affect, however, the properties of fresh and hardened concrete in different ways, and this should be taken into account when proportioning concrete containing these fly ashes. Key words: fly ash, concrete, pozzolanic activity index, bleeding, setting time, air-entrainment, strength, creep, shrinkage, freezing and thawing.

scholarly journals Waste Slag from Heating Plants as a Partial Replacement for Cement in Mortar and Concrete Production. Part I—Physical–Chemical and Physical–Mechanical Characterization of Slag

Minerals ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 992
Author(s):  
Andrijana Nedeljković ◽  
Marija Stojmenović ◽  
Jelena Gulicovski ◽  
Nenad Ristić ◽  
Sonja Milićević ◽  
...  
Keyword(s):  
Silica Fume ◽  
Mechanical Characterization ◽  
Setting Time ◽  
Partial Replacement ◽  
Minimal Amount ◽  
Cement Replacement ◽  
Physical Chemical ◽  
Concrete Production

Numerous factors influence the complexity of environmental and waste management problems, and the most significant goal is the reuse of materials that have completed their “life cycle” and the reduction in the use of new resources. In order to reduce impact of waste slag on the environment, in the present study, waste slag, generated in heating plants after lignite combustion, was characterized in detail and tested for application as a replacement for cement in mortar or concrete production. For physical–chemical characterization of slag, different experimental and instrumental techniques were used such as chemical composition and determination of the content of heavy metals, investigation of morphological and textural properties, thermal analysis, X-ray, and infrared spectroscopy. Physical–mechanical characterization of slag was also performed and included determination of activity index, water requirement, setting time and soundness. A leaching test was also performed. Presented results show that waste slag may be used in mortar and concrete production as a partial cement replacement, but after additional combustion at 650 °C and partial replacement of slag with silica fume in the minimal amount of 12%. The maximal obtained cement replacement was 20% (17.8% slag and 2.2% of silica fume).

scholarly journals The relationship between transmission time and clustering methods inMycobacterium tuberculosisepidemiology

2018 ◽  
Author(s):  
Conor J Meehan ◽  
Pieter Moris ◽  
Thomas A. Kohl ◽  
Jūlija Pečerska ◽  
Suriya Akter ◽  
...  
Keyword(s):  
Democratic Republic Of Congo ◽  
Setting Time ◽  
Whole Genome Sequence ◽  
Clustering Methods ◽  
Time Period ◽  
Recent Transmission ◽  
Clustering Data ◽  
The Relationship ◽  
Selection Of

AbstractBackgroundTracking recent transmission is a vital part of controlling widespread pathogens such asMycobacterium tuberculosis. Multiple methods with specific performance characteristics exist for detecting recent transmission chains, usually by clustering strains based on genotype similarities. With such a large variety of methods available, informed selection of an appropriate approach for determining transmissions within a given setting/time period is difficult.MethodsThis study combines whole genome sequence (WGS) data derived from 324 isolates collected 2005-2010 in Kinshasa, Democratic Republic of Congo (DRC), a high endemic setting, with phylodynamics to unveil the timing of transmission events posited by a variety of standard genotyping methods. Clustering data based on Spoligotyping, 24-loci MIRU-VNTR typing, WGS based SNP (Single Nucleotide Polymorphism) and core genome multi locus sequence typing (cgMLST) typing were evaluated.FindingsOur results suggest that clusters based on Spoligotyping could encompass transmission events that occurred over 70 years prior to sampling while 24-loci-MIRU-VNTR often represented two or more decades of transmission. Instead, WGS based genotyping applying low SNP or cgMLST allele thresholds allows for determination of recent transmission events in timespans of up to 10 years e.g. for a 5 SNP/allele cut-off.InterpretationWith the rapid uptake of WGS methods in surveillance and outbreak tracking, the findings obtained in this study can guide the selection of appropriate clustering methods for uncovering relevant transmission chains within a given time-period. For high resolution cluster analyses, WGS-SNP and cgMLST based analyses have similar clustering/timing characteristics even for data obtained from a high incidence setting.

scholarly journals Study on Modification of Alkali-Free Liquid Accelerator of Mine-Used Wet-Mix Shotcrete

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Chen Lianjun ◽  
Li Pengcheng ◽  
Pan Gang ◽  
Bian Wenhui
Keyword(s):  
Spatial Structure ◽  
Bond Strength ◽  
Research And Development ◽  
Setting Time ◽  
Coal Mines ◽  
Optimum Dose ◽  
High Polymer ◽  
Pore Characteristics ◽  
Time Strength

Compound properties of an alkali-free liquid accelerator are the mainstream of accelerator research and development in the present. Combined with the technical characteristics of wet-mix shotcrete in coal mines, organic high-polymer SWF is used to modify the accelerator because of improving the bond strength of the material and increasing the performance of antisagging. The mechanism of filling and thickening of SWF was analyzed from the aspects of pore characteristics and spatial structure of concrete. Through the determination of setting time, strength, and dispersibility, the optimum dose was determined, and a new style accelerator WIT-1 suitable for wet-mix shotcrete in coal mines was developed and applied on-site. The experimental results show that the addition of SWF increases the dispersibility of the accelerator product and the cohesiveness of concrete under the condition of ensuring strength and setting time, and the effect of modifying the accelerator to reduce the rebound of the wet-mix shotcrete is obvious.

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