Versuche zum Schwinden und Kriechen von Beton unter Berücksichtigung des Feuchtegehalts/Tests on shrinkage and creep behavior of concrete taking into account the moisture content

Bauingenieur ◽  
2018 ◽  
Vol 93 (03) ◽  
pp. 95-102 ◽  
Author(s):  
M. Drexel ◽  
Y. Theiner ◽  
G. Hofstetter
Keyword(s):  
Moisture Content ◽  
Creep Behavior ◽  
Shrinkage And Creep ◽  
C 30 ◽  
Zeitliche Entwicklung

Im vorliegenden Beitrag wird ein umfangreiches Versuchsprogramm zum Schwinden und Kriechen unter Druckbeanspruchung eines Betons der Festigkeitsklasse C 30/37 vorgestellt. An versiegelten und unversiegelten zylindrischen Probekörpern wurde die zeitliche Entwicklung (i) der autogenen Schwinddehnungen, (ii) der kombinierten autogenen Schwind- und Trocknungsschwinddehnungen, (iii) der totalen Dehnungen von im Alter von zwei, sieben und 28 Tagen mit 30 % der jeweiligen Druckfestigkeit belasteten Probekörpern und (iv) des Feuchtegehalts der Schwind- und Kriechprobekörper ermittelt. Dadurch konnte der Einfluss der Druckbelastung auf den Feuchtegehalt in Abhängigkeit des Betonalters bei Belastungsbeginn sowie der Einfluss des Feuchteaustausches zwischen Probekörper und trockenerer Umgebungsluft auf das Kriechen (Pickett-Effekt) und Schwinden von Beton untersucht werden. Zusätzlich wurde die Desorptionsisotherme für fünf verschiedene Werte der relativen Luftfeuchtigkeit ermittelt sowie die zeitliche Entwicklung der Druckfestigkeit und des Elastizitätsmoduls jeweils an bis zur Prüfung versiegelten Probekörpern bestimmt.

Physical and Viscoelastic Properties of Different Moisture Content Highland Barley Kernels

2017 ◽  
Vol 13 (12) ◽  
Author(s):  
Ying-dan Zhu ◽  
Nan Fu ◽  
Dong Li ◽  
Li-jun Wang ◽  
Xiao Dong Chen
Keyword(s):  
Moisture Content ◽  
Creep Behavior ◽  
Viscoelastic Properties ◽  
Time Frame ◽  
Kernel Weight ◽  
Dorsal Side ◽  
Burgers Model ◽  
Moisture Contents ◽  
Barley Kernel ◽  
Highland Barley

Abstract:The study is conducted to investigate the physical and viscoelastic properties of the highland barley kernels in different moisture content range from 10.1 %% to 20.5 %% (w.b.). Highland barley kernel samples were selected with physical properties in terms of length, width, thickness, 1000-kernel weight, volume, geometric and arithmetic mean diameter changing in linear trends. By using a dynamic mechanical analyzer, the 4-element Burgers model was found to adequately represent the creep behavior of the highland barley kernels (R2> 0.977). The creep behavior of the ventral groove and dorsal side was also matched perfectly with Burgers model (R2> 0.946). The creep behavior of these kernels at long-time frame was studied applying time-temperature superposition (TTS). TTS method was successfully used to predict the creep behavior of these kernels at longer frame of time. TheTgvalues for the kernels decreased with increasing moisture content. TheTgvalues for the kernels at the moisture contents of 10.1 %%and 20.5 %% were 114.33 °C and 67.95 °C, respectively. The magnitude of the storage modulus, loss tangent and their change rates with frequency were maximum at 10.1 %% and minimum at 20.5 %% moisture contents.

The creep of wood destabilized by change in moisture content. Part 3: The influence of changing moisture history on creep behavior

Holzforschung ◽  
2006 ◽  
Vol 60 (3) ◽  
pp. 299-303 ◽  
Author(s):  
Chika Takahashi ◽  
Yutaka Ishimaru ◽  
Ikuho Iida ◽  
Yuzo Furuta
Keyword(s):  
Mechanical Properties ◽  
Moisture Content ◽  
Memory Effect ◽  
Creep Behavior ◽  
Cell Walls ◽  
Load Level ◽  
Moisture Change ◽  
Adsorption Processes ◽  
Rapid Adsorption

Abstract The creep of wood increases remarkably during moisture changes, a phenomenon called mechano-sorptive creep. The microstructure in cell walls of wood is destabilized by changes in temperature and/or moisture content. The mechanical properties of destabilized wood change over long periods of time. In the present study, the influence of moisture conditioning history on bending creep was examined. During changes in moisture, greater creep occurred in wood subjected to the first moisture change after long-term moisture conditioning than immediately after desorption or adsorption. This result indicates a kind of memory effect immediately after moisture change. During desorption processes, greater creep occurred immediately after slow adsorption than immediately after rapid adsorption. In the course of adsorption, the reverse was observed: the creep was greater immediately after rapid desorption than immediately after slow desorption. Accordingly, greater instability immediately after a change in moisture does not always cause greater creep during the next moisture change. The size of the moisture change and the load level affect the recovery of creep during adsorption processes.

Experimental Study on C60 High Performance Concrete with High Content Mineral Additives and Low Shrinkage Creep

2014 ◽  
Vol 1030-1032 ◽  
pp. 978-982
Author(s):  
Xiao Jun Lu ◽  
Zhi Da Li ◽  
Ping Zhang
Keyword(s):  
Experimental Study ◽  
Creep Behavior ◽  
High Performance ◽  
Work Performance ◽  
High Performance Concrete ◽  
Good Work ◽  
Shrinkage And Creep ◽  
Binder Ratio ◽  
Mineral Additives ◽  
Water Binder Ratio

Shrinkage and creep behavior of concrete are keys that affect bridge construction and usage. The C60 high performance concrete was prepared by adding high content mineral additives and reducing water-binder ratio. This kind of concrete has good work performance and higher pumpability. It also has a low shrinkage and creep feature. Experiments were carried out to compare performance to concrete without mineral additives. Results show that its shrinkage and creep value decrease about 30% to 50% within long age of 360 days.

Moisture content effect on the creep behavior of loess for the catastrophic Baqiao landslide

CATENA ◽  
2020 ◽  
Vol 187 ◽  
pp. 104371 ◽  
Author(s):  
Xingang Wang ◽  
Jiading Wang ◽  
Hongbin Zhan ◽  
Ping Li ◽  
Haijun Qiu ◽  
...  
Keyword(s):  
Moisture Content ◽  
Creep Behavior

Heat as a phytosanitary treatment for the brown spruce longhorn beetle

2004 ◽  
Vol 80 (2) ◽  
pp. 224-228 ◽  
Author(s):  
Lisa Mushrow ◽  
Andrew Morrison ◽  
Jon Sweeney ◽  
Dan Quiring
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treated Wood ◽  
Larval Survival ◽  
Wood Products ◽  
Longhorn Beetle ◽  
Different Temperatures ◽  
Phytosanitary Measures ◽  
C 30 ◽  
Tetropium Fuscum

The brown spruce longhorn beetle (BSLB), Tetropium fuscum (Fabr.), is native to Europe but has recently been discovered in Halifax, Nova Scotia, where efforts are underway to eradicate it. If attempts to eradicate this beetle are unsuccessful, phytosanitary measures will have to be developed to ensure continued access to markets. We carried out studies to determine the lethal temperatures for different BSLB life stages in spruce. The beetles were exposed to different temperatures for various time periods in lumber of low and high moisture content. Adults died after 30 and 15 minutes exposure to 40 and 45°C, respectively, and pupae died after 30 minutes exposure to 45°C. Larvae required exposure to 50°C for 30 minutes (or 55°C for 15 minutes) to ensure 100% mortality. Larval survival was slightly higher in wood with low moisture content. The study was repeated a second year for the 50°C/30-minute and 55°C/15-minute treatments for larvae and the 45°C/30-minute for pupae at very low moisture (12-15% oven-dry basis) content, with similar results. Our results demonstrate that heat treatment is an effective phytosanitary method to ensure that wood does not contain any live BSLB.Current phytosanitary guidelines listed by the Canadian Food Inspection Agency in its directive "Canadian Heat-treated Wood Products Certification Program (CHTWPCP) for Export" (56ºC, 30 minutes) are more than adequate to ensure BSLB-free wood. Key words: brown spruce longhorn beetle, heat treatment, hygrothermal stress, Tetropium fuscum, wood borers

scholarly journals Kajian Perubahan Mutu Selama Penyimpanan Dan Pendugaan Umur Simpan Keripik Ikan Beledang Dalam Kemasan Polypropylene Rigid

2015 ◽  
Vol 7 (1) ◽  
pp. 1-6
Author(s):  
Yessy Rosalina ◽  
Evanila Silvia
Keyword(s):  
Moisture Content ◽  
Shelf Life ◽  
Water Content ◽  
Life Prediction ◽  
Storage Temperature ◽  
Quality Changes ◽  
Arrhenius Model ◽  
Shelf Life Prediction ◽  
C 30

(Study Of Quality Changes During Storage And Shelf Life Prediction Of Beledang Fish Chips In Rigid Polypropylene Packaging) ABSTRACT. This research aims to determine the quality changes during storage and shelf life of beledang fish chips in rigid polypropylene packaging. Observation of quality based on the moisture content and total microbes were done on 0 and 30th days at 25°C, 30°C and 35°C with 3 replicates at each storage temperature. Shelf life prediction of beledang fish chips based on moisture content changes at 25oC, 30oC dan 35oC was measured using Arrhenius Model. The result shows that there is a change in water content and total microbes in beledang fish chips during storage. At storage temperature of 35oC, the chips have moisture content changes and total microbes on the 30th day of storage which are 4% and 10 x 104Cfu. The shelf life of beledang fish chips in polypropylene rigid packaging at storage temperature of 25oC, 30oC and 35oC is 9 months 28 days, 10 months 3 days, and 10 months 8 days respectively.

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