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Showing 3 results for Pull Out

M. Khorami, J. Sobhani,
Volume 11, Issue 4 (12-2013)
Abstract

Worldwide, asbestos fibers utilized in fiber cement boards, have been recognized as harmful materials regarding the public health and environmental pollutions. These concerns motivate the researchers to find the appropriate alternatives to substitute the asbestos material towards the sustainability policies. In this paper, the applicability of asbestos replacement with three types of agricultural waste fibers, including bagasse, wheat and eucalyptus fibers were experimentally investigated. To this end, the flexural behaviour and microstructure of cement composite boards made by addition of 2 % and 4 % of waste agricultural fibers in combination with and without 5 % replacement of silica fume by mass of cement were evaluated. The results of this study attested the applicability of utilized waste agricultural fibers in production of cement composite boards by improving the flexural and energy absorption characteristics, more or less, depending on the type of fibers. Moreover, it is found that application of silica fume in production of cement composite boards led to an increase in flexural strength.
M. Zargaran, N. K. A. Attari, P. Teymouri,
Volume 12, Issue 1 (3-2014)
Abstract

Polymeric yarns for reinforcing cement composites have got great interest in all over the world. In this research the performance of bonding between Nylon tire cord grad yarns, and one kind of cement composite called fine grained concrete was studied. Two kinds of Nylon cord yarns, nylon 6 and 66, with different finesse were selected. The durability of yarns with time in alkaline media was investigated. Meanwhile the effect of usual tire cord coating on bonding performance and alkaline durability of yarns were studied by mechanical testing and SEM images. Then the bonding of these yarns to cement paste and the effects of finesse on bonding performance were investigated by pull out tests. The results show that coating could enhance alkaline durability. Results also show that yarns with higher finesse are more sensitive to alkaline media and their mechanical properties reduced more. SEM images show that in general, alkali damage of Nylon tire cord yarns was not deep and no significant changes were observed on the surface of filaments after exposed to alkali. The bonding of Nylon tire cord to cement composite was suitable and no slippage was observed. The pull out behavior of finer yarns is better than coarse yarns. Meanwhile tire cord coating could enhance bonding of yarns to cement paste.
A. Eslami, I. Tajvidi, M. Karimpour-Fard,
Volume 12, Issue 1 (1-2014)
Abstract

Three common approaches to determine the axial pile capacity based on static analysis and in-situ tests are presented, compared and evaluated. The Unified Pile Design (UPD), American Petroleum Institute (API) and a SPT based methods were chosen to be validated. The API is a common method to estimate the axial bearing capacity of piles in marine environments, where as the others are currently used by geotechnical engineers. Seventy pile load test records performed in the northern bank of Persian Gulf with SPT profile have been compiled for methods evaluation. In all cases, pile capacities were measured using full scale static compression and/or pull out loading tests. As the loading tests in some cases were in the format of proof test without reaching the plunging or ultimate bearing capacity, for interpretation the results, offset limit load criteria was employed. Three statistical and probability based approaches in the form of a systematic ranking, called Rank Index, RI, were utilized to evaluate the performance of predictive methods. Wasted Capacity Index (WCI) concept was also applied to validate the efficiency of current methods. The evaluations revealed that among these three predictive methods, the UPD is more accurate and cost effective than the others.

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