Minimisation of Water Content in Concrete

2016 ◽  
Vol 691 ◽  
pp. 230-238
Author(s):  
Ivan Juríček ◽  
Ľudovít Fillo
Keyword(s):  
Moisture Content ◽  
Water Content ◽  
Atmospheric Pressure ◽  
Bound Water ◽  
Free Water ◽  
Point Of View ◽  
Free Water Content ◽  
Normal Atmospheric Pressure ◽  
Moisture Characteristic ◽  
Short Time

In the production of structures made of concrete it is sometimes required to make a completed structure contain a minimum amount of free water. From the point of view of effectiveness of the production process it is also preferred to dry the concrete in a short time and at a reasonable cost. Required for free water content can be limited by various factors (e.g. construction covered by flooring sensitive to humidity, frost resistance, etc.).The moisture characteristic of concrete is verified in civil engineering provided that the concrete is located in the environment with normal atmospheric pressure. By solving the project “Development of methods for structure of thermal vacuum insulated containers” we have met a requirement to produce concrete with extremely low moisture content. It was found out that information about moisture content of concrete obtained by currently used method was unsatisfactory for concrete in the environment with extremely low atmospheric pressure. The research has indicated that usual methods of concrete drying are not sufficient for concrete subjected to vacuum because they don´t eliminate physically bound water.

Influence of the free water content on the dewaterability of sewage sludges

2001 ◽  
Vol 44 (10) ◽  
pp. 177-183 ◽  
Author(s):  
J. Kopp ◽  
N. Dichtl
Keyword(s):  
Binding Energy ◽  
Sewage Sludge ◽  
Water Content ◽  
Water Distribution ◽  
Bound Water ◽  
Free Water ◽  
Binding Energies ◽  
Intracellular Water ◽  
Water Binding ◽  
Free Water Content

Dewaterabilty of sewage depends on the physical water distribution. The various types of water in sewage sludge are mainly distinguished by type and intensity of their physical bonding to the solids. In a sewage sludge suspension different types of water can be distinguished. These are free water, which is not bound to the particles, interstitial water, which is bound by capillary forces between the sludge flocs, surface water, which is bound by adhesive forces and intracellular water. Only free water can be separated during mechanical dewatering. It can be shown, that thermo-gravimteric measurement of the free water content leads to an exact prediction of full-scale dewatering results. Maximum dewatering results are reached by separating all free water during centrifugation. Furthermore on the basis of the drying curve an estimation of water binding energies can be achieved. The binding energy for free water is less than 0,28 kJ/kg water. The binding energy for bound water (sum of surface and intracellular water) is higher than 5 kJ/kg water.

Characterization of thin water layers in pulp by tritium exchange. Part 1: Methods development

Holzforschung ◽  
2007 ◽  
Vol 61 (2) ◽  
pp. 115-119 ◽  
Author(s):  
Frances L. Walsh ◽  
Sujit Banerjee
Keyword(s):  
Water Content ◽  
Surface Area ◽  
Tritiated Water ◽  
Bound Water ◽  
Free Water ◽  
Fiber Surface ◽  
Bulk Water ◽  
Methods Development ◽  
A Value ◽  
A New Technique

Abstract A new technique for measuring the monolayer water content of fiber is presented. Tritiated water is added to a pulp/water suspension, whereupon the tritium partitions between the bulk water and the pulp. In the pulp phase the tritium can exchange with free water, bound water, and with hydroxyl and other protons present in the pulp matrix. The free water in the pulp is then removed by displacement with acetone. The tritium remaining in the pulp is mostly associated with tightly bound water, with a small fraction being tied up with the exchangeable hydrogen in pulp. The procedure provides a value of 10% for the tightly bound water content of hardwood or softwood fiber, either bleached or unbleached. If this water is assumed to cover the fiber surface as a monolayer, then an estimate of the wet surface area of the fiber can be obtained. This estimate compares well with independent measurements of surface area.

Fermentation Problem in Spanish North-Coast Honey

1995 ◽  
Vol 58 (5) ◽  
pp. 515-518 ◽  
Author(s):  
SUSANA SANZ ◽  
GLORIA GRADILLAS ◽  
FUENCISLA JIMENO ◽  
CONSUELO PEREZ ◽  
TERESA JUAN
Keyword(s):  
Water Content ◽  
Water Activity ◽  
Microbiological Quality ◽  
Free Water ◽  
High Water ◽  
North Coast ◽  
High Water Content ◽  
Free Water Content ◽  
Cantabrian Coast ◽  
Mold And Yeast

Twenty-one samples from the Cantabrian coast were analyzed to establish their microbiological quality and fermentation tendency. In a food with a very low free-water content like honey, microbiological growth is only possible when there is an increase in water activity. Since most of the samples studied were not extensively granulated, the risk of fermentation is mostly due to high water content. Among our samples, only two had a water content below 17.1% (no risk of fermentation), whereas the high water activity of the rest of the samples indicates the possibility of microbial growth. In fact, four of the samples analyzed showed a moisture content over the Spanish maximum legal limit, which means a high risk of fermentation. The absence of Enterobacteriaceae, coliforms, and Escherichia coli in our samples indicates an appropriate cleanliness during extractions and handling of honey. No Salmonella or Shigella were found. The relationship between water activity and mold and yeast counts found for the honeys analyzed allowed us to divide our samples in two groups: honeys with a high or a low risk of fermentation. Changes observed during storage of the samples confirmed this classification.

Short-Term Snow Melt and Ablation Derived from Heat- and Mass-Balance Measurements

1973 ◽  
Vol 12 (65) ◽  
pp. 275-289 ◽  
Author(s):  
Paul M. B. Föhn
Keyword(s):  
Mass Balance ◽  
Water Content ◽  
Free Water ◽  
Liquid Water Content ◽  
Snow Melt ◽  
Snow Pack ◽  
Density Profiles ◽  
Run Off ◽  
Free Water Content ◽  
Meteorological Observations

AbstractThe daily snow melt calculated from meteorological observations is compared with detailed mass-balance measurements taking into account internal changes in density and free water content in the surface layers of a glacier snow-pack. The energy balance is calculated from measurements obtained by a meteorological station at the experimental site. In addition to the standard ablation measurements the run-off from the melting snow-pack was obtained for a few days. The snow-density profiles were measured with a portable gamma-transmission probe and the liquid-water content of snow was determined by a calorimetric method.Agreement between the melt calculated by the heat-balance method and the mass changes observed in the mass-balance measurements is fair for daily periods. It appears that about 20% of the daily snow melt takes place internally as a result of penetration of solar radiation.

Infrared Measurement Of Free-Water Content And Grain Size Of Snow

1987 ◽  
Vol 26 (4) ◽  
pp. 264342 ◽  
Author(s):  
T. Hyvarinen ◽  
J. Lammasniemi
Keyword(s):  
Grain Size ◽  
Water Content ◽  
Free Water ◽  
Free Water Content ◽  
Infrared Measurement
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