scholarly journals Influences of Environmental Conditions on the Cracking Tendency of Dry-Mixed Plastering Mortar

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Ni Tongyuan ◽  
Yang Yang ◽  
Wu Dandan ◽  
Jiang Chenhui

Cracking tendency is one of the important performances of dry-mixed plastering mortar (DMPM). Environmental condition is a key factor to affect the cracking tendency of DMPM. For the purpose of evaluating the cracking resistance of DMPM and revealing the influence of environmental conditions on the cracking tendency of DMPM, a series of experiments were performed on restriction-induced cracking behaviors as well as free shrinkage, water loss, and mechanical properties of DMPM. The restricted shrinkage tests were based on ring tests and plate experiments. The results showed that the initial drying age exhibits significant influence on the cracking tendency of DMPM, and there was a stress balance period when the initial drying age was 2 days. But, the phenomena cannot be observed when the initial age was 3 d, 5 d, and 7 d. In order to eliminate the cracking tendency of DMPM, it should avoid water loss from the plaster layer during construction in practical engineering, especially, before initial drying ages.

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3755
Author(s):  
Štefan Gašpár ◽  
Tomáš Coranič ◽  
Ján Majerník ◽  
Jozef Husár ◽  
Lucia Knapčíková ◽  
...  

The resulting quality of castings indicates the correlation of the design of the mold inlet system and the setting of technological parameters of casting. In this study, the influence of design solutions of the inlet system in a pressure mold on the properties of Al-Si castings was analyzed by computer modelling and subsequently verified experimentally. In the process of computer simulation, the design solutions of the inlet system, the mode of filling the mold depending on the formation of the casting and the homogeneity of the casting represented by the formation of shrinkages were assessed. In the experimental part, homogeneity was monitored by X-ray analysis by evaluating the integrity of the casting and the presence of pores. Mechanical properties such as permanent deformation and surface hardness of castings were determined experimentally, depending on the height of the inlet notch. The height of the inlet notch has been shown to be a key factor, significantly influencing the properties of the die-cast parts and influencing the speed and filling mode of the mold cavity. At the same time, a significant correlation between porosity and mechanical properties of castings is demonstrated. With the increasing share of porosity, the values of permanent deformation of castings increased. It is shown that the surface hardness of castings does not depend on the integrity of the castings but on the degree of subcooling of the melt in contact with the mold and the formation of a fine-grained structure in the peripheral zones of the casting.


2021 ◽  
Vol 176 ◽  
pp. 111498 ◽  
Author(s):  
Sebastian Rivera ◽  
Huub Kerckhoffs ◽  
Svetla Sofkova-Bobcheva ◽  
Dan Hutchins ◽  
Andrew East

Neuroforum ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lisa Spiecker ◽  
Bo Leberecht ◽  
Corinna Langebrake ◽  
Malien Laurien ◽  
Shambhavi Rajendra Apte ◽  
...  

Abstract Every year, billions of animals leave their home range and start seasonal migrations in order to find more favorable resources and to escape harsh environmental conditions. These round trips often span thousands of kilometers. To successfully navigate along their route, animals rely on various external references. While landmarks and celestial cues like stars or the sun are easy to imagine as guidance on these journeys, using the geomagnetic field for orientation is more elusive. The geomagnetic field is an omnipresent cue, which can be sensed and relied upon by many animals, even when visual cues are sparse. How magnetic fields can be perceived seems to vary between birds and fish. While birds seem to use a mechanism based on the quantum mechanical properties of electron spins, fish may have evolved a compass similar in its function to the technical devises developed by humans. How these mechanisms work precisely and how they are integrated are research questions addressed in SFB 1372.


1972 ◽  
Vol 35 (2) ◽  
pp. 98-101 ◽  
Author(s):  
P. P. Graham ◽  
T. N. Blumer

Hams were frozen, stored, and thawed before dry-curing to study the profiles of quality as related to environmental conditions. Quality appraisals and sampling were done after thawing, after curing, and after 30 days aging in an atmosphere where temperature and relative humidity were controlled at about 34.5 C and 62.5%, respectively. The pH, water, NaCl, and fat contents were determined. Surface pH of hams increased from the thawed fresh state to the unstored cured state, but decreased generally after the aging period (stored cured ham). The pH was higher on the surface than that of corresponding internal areas. The pH of the internal tissue was lower for thawed product than cured or aged product. The average percent water decreased during curing and aging periods. Water loss after curing and after aging in the prefrozen hams was greater than that reported for unfrozen hams. The quantity of water, NaCl, and fat varied among the several muscle areas and reasons for variation are discussed. All hams were of acceptable quality at each appraisal period. Decreasing moisture levels of hams were reflected by decreases in conformation scores throughout the processing periods. Increased firmness was accompanied by weight loss, moisture loss, and increased NaCl percentage.


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