ارائه روشي جديد مبتني بر شبيه سازي كامپيوتري جهت تخمين چگالي چيدمان﴿PD﴾مخلوط سنگدانه ها در طرح اختلاط بتن

چكيده انگليسي :

Advanced Materials Research Vol 337 2011 pp 313 316Online available since 2011 Sep 02 at www scientific net 2011 Trans Tech Publications Switzerlanddoi 10 4028 www scientific net AMR 337 313 A Numerical Method to Predict Packing Density of Aggregates in Concrete Mohammad Reisi1 a Davood Mostofi Nejad2 b 1 PhD student of civil engineering Isfahan University of Technology IUT Isfahan IRAN 2 Professor of civil engineering Isfahan University of Technology IUT Isfahan IRAN a m reisi@cv iut ac ir b dmostofi@cc iut ac irKeywords Aggregate grading packing density PD discrete element method DEM Abstract It is nowadays very clear that the single most important parameter influencing theperformance of concrete is the packing density of the aggregates Among aggregate characteristics grading of aggregates has the most significant effect on packing density PD of aggregates In thecurrent sstudy packing density of five aggregates were measured by experimental tests andcomputer simulation base on discrete element method DEM Obtained results show that theperformed computer simulation is very efficient method to predict packing density and optimizationgrading of aggregates IntroductionThe properties and behavior of particulate composite materials such as concrete depend on theproperties of their main constituent Aggregates which occupy 60 to 80 of the total volume ofconcrete are the main constituent of concrete Aggregates shape texture and grading havesignificant effects on the performance of fresh and hardened concrete Aggregate blends with highpacking density require low amounts of paste to fulfill voids between aggregates 1 and as a result they are less expensive and will have less durability problems caused by the paste such as highhydration drying shrinkage and creep It is nowadays very clear that the single most importantparameter influencing the performance of concrete is the packing density of the aggregate Amongaggregate characteristics the particle size distribution PSD or grading of aggregates has the mostsignificant effect on packing density PD of aggregates One of the methods for optimization ofconcrete mixtures is to combine available aggregates in such a way that maximum or nearmaximum packing degree is obtained while maintaining an acceptable level of workability Optimization packing density of aggregates was objective of many researches in recent century Many researchers tried to relate between grading and packing density of aggregates Someresearchers have presented numerical model according to laboratory tests and some packingtheories to estimate packing density of aggregates 1 5 Some others used computer simulation tomodel packing density of aggregates 6 9 In the following sections these attemps will beexplained Packing density modelsThe packing density of a granular mix is defined as the solid volume in a unit total volume Ifvolume of aggregate in a container and volume of container be Vs and V respectively the packingdensity og aggregates is determine by Eq 1 Vs 1 VThe use of reliable packing models provides a useful tool for optimization of the aggregate blends which will lead to a more optimal use of the aggregates and to a cheaper concrete with an improvedquality In the recent century many efforts have been done by researchers to relate between packingdensity and characteristics of aggregate blends The first useful models that give the best fit of theAll rights reserved No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of TTP www ttp net ID 188 158 129 194 25 04 12 13 20 11

رئيسي، محمد

ارائه روشي جديد مبتني بر شبيه سازي كامپيوتري جهت تخمين چگالي چيدمان﴿PD﴾مخلوط سنگدانه ها در طرح اختلاط بتن

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