scholarly journals Time-dependent mechanical behavior of lime-mortar masonry

2010 ◽  
Vol 44 (1) ◽  
pp. 29-42 ◽  
Author(s):  
Els Verstrynge ◽  
Luc Schueremans ◽  
Dionys Van Gemert
Blood ◽  
1990 ◽  
Vol 76 (12) ◽  
pp. 2606-2612 ◽  
Author(s):  
RS Frank

Abstract Transit times of individual human neutrophils through single capillary- sized pores were measured to determine the time-dependent changes in the mechanical behavior of the cells during activation by the chemotactic agent formyl-methionyl-leucyl-phenylalanine (FMLP) and in response to cytochalasin B (CTB) and colchicine. FMLP elicited a two- phase response consisting of a rapid increase in cell stiffness, which peaked between 2 and 3 minutes, followed by a partial recovery of deformability to a level significantly above that of control after 5 minutes. The mechanical changes closely followed changes in F-actin content, although the peak in cell stiffness appeared to lag the F- actin response. Treatment with 3 mumols/L CTB produced a transient decrease in cell rigidity followed by a return to control level in 10 minutes, whereas treatment with 30 mumols/L CTB resulted in a sustained decrease in cell transit times to a level 60% of control. Addition of 3 mumols/L CTB to cells prestimulated with FMLP produced a rapid (1 to 2 minutes) cessation of changes in cellular deformability produced by the FMLP. Colchicine treatment did not decrease cell rigidity, but produced a delayed increase in F-actin content accompanied by increased stiffness of the cells. These results implicate actin as the major determinant of the mechanical behavior of the neutrophil, as measured by whole cell deformability tests. The significant changes in cell deformability that occur in response to fractional changes in F-actin content suggest that changes in the structure of the actin network occur during these processes.


2008 ◽  
Author(s):  
I. Emri ◽  
U. Florjancic ◽  
B. Zupancic ◽  
M. Huskic ◽  
M. Zigon ◽  
...  

2011 ◽  
Vol 675-677 ◽  
pp. 435-438
Author(s):  
Wei Xiang Zhang ◽  
Xing Shao ◽  
Zhao Ran Xiao

Polymers have been proved to have attractive mechanical characteristics, which made it desirable to choose these materials over traditional materials for numerous types of applications. As the uses of polymers increase, a thorough understanding of the mechanical behavior of these materials becomes vital in order to perform innovative and economical designs of various components. The main objective of this paper is to develop an effective method with the use of the Laplace inverse transform to describe the time dependent mechanical response of viscoelastic polymers. This general methodology is based on differential constitutive relations for viscoelastic polymers, avoiding the use of relaxation integral functions. As its application, the creep and relaxation properties of the materials are exhibited in the numerical examples.


2008 ◽  
Vol 12 (4) ◽  
pp. 357-364 ◽  
Author(s):  
F. J. Rubio-Hernández ◽  
A. I. Gómez-Merino

2012 ◽  
Vol 27 ◽  
pp. 26-30 ◽  
Author(s):  
H.S. Chou ◽  
X.H. Du ◽  
J.C. Huang ◽  
T.G. Nieh

Author(s):  
Mônica Navarini Kurz ◽  
Charlei Marcelo Paliga ◽  
Ariela da Silva Torres

RESUMO: O setor da construção civil vem absorvendo resíduos e transformando-os em componentes para utilização nas construções, especialmente através da incorporação em materiais como argamassas e concretos. Com o crescente número de veículos automotivos, ocorreu um aumento na produção de pneus e, consequentemente, de seus resíduos. Portanto, o presente estudo tem o objetivo de avaliar o melhor teor de substituição de agregado miúdo por resíduo de borracha em argamassa de cimento e cal, a partir da comparação com uma argamassa de referência, analisando o comportamento físico e mecânico. Para verificar a melhor relação de substituição, os ensaios foram realizados em argamassa referência (traço 1:2:9) e em argamassas com resíduos nas proporções de 2,5%, 5%, 10% e 15% de substituição de areia por borracha. Para caracterização das argamassas foram realizados ensaios de índice de consistência, resistência à compressão axial, resistência à tração por compressão diametral, absorção por capilaridade e absorção por imersão. Os resultados indicam que nas argamassas com resíduo ocorreu um aumento na relação a/c para se manter a trabalhabilidade e um decréscimo nas resistências. Além de, uma diminuição na absorção por capilaridade e um aumento na absorção por imersão. Apesar de provocar mudanças no comportamento da argamassa, aponta-se o uso desse resíduo como alternativa viável, tanto ambiental quanto de desempenho.ABSTRACT: The construction industry has been absorbing and transforming them into components for use in construction, especially through the incorporation of materials such as mortars and concretes. With the increasing number of automotive vehicles, there has been an increase in the production of tires and, consequently, of their waste. Therefore, the present study has the objective of evaluating the best content of substitution of small aggregate by rubber residue in cement and lime mortar, from the comparison with a reference mortar, analyzing the physical and mechanical behavior. To verify the best substitution ratio, the tests were performed in reference mortar (trace 1:2:9) and mortar with residuals in the proportions of 2.5%, 5%, 10% and 15% of Sand for rubber. To characterize the mortars, tests of consistency index, axial compression strength, tensile strength by diametrical compression, capillary absorption and immersion absorption were performed. The results indicate that in the mortars with residue an increase in the w/c ratio was observed to maintain the workability and a decrease in the resistances. In addition to, a decrease in capillary absorption and an increase in absorption by immersion. Although it causes changes in mortar behavior, the use of this residue is indicated as a viable alternative, both environmental and performance.


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