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چكيده انگليسي :

131 Optimization Of Self Compacting lightweight Concrete Mix Design By Using Design Of Experiments Statistical Method Habib Pashaei h pashaei@cv iut ac ir August 2014 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Kiachehr Behfarnia kia@cc iut ac irAbstractDue to weakness of constructing performances low efficient human resources andcountry s seismicity condition reducing weight and increasing quality of concretestructures seems to be neccessary Thus using lightweight aggregate and self compactingconcrete could be considered as an appropriate solution So far due to numerousadvantages of self compacting concretes extensive researches have been done on it Butnevertheless a small portion of those researches has been devoted to self compactinglightweight concrete SCLC Therefore better understanding of SCLC in fresh andhardened state was an objective of this thesis In the present research lightweight expandedclay aggregate liapor has been used for reducing weight Also increasing compressivestrength of produced concrete was one of the main goals in this thesis hence in order toreducing laboratory costs and optimizing results in designing and analyzing experiments Taguchi statistical method was used Since there are several variables affecting fresh andhardened state behavior of high performance concretes in the present research coarseaggregate volume sand to mortar ratio water to powder ratio and silica fume replacementpercentage as effective factors in four different levels were selected Therefore inconducting this research 444 samples were tested and analyzed In the Concrete fresh state Slump Flow with T500 and the visual stability index VSI L box and V funnel was used for evaluating self compactibility criteria In studying test sperformances it has been found that L Box is not suitable for detecting segregation dueto buoyancy and maximum size of aggregates Also neither VSI is necessarily effective forthese types of concrete In addition suitable range of V Funnel for identify selfcompactibility were observed different from SCC with regular aggregates In general themost important factor influencing the test results in concrete fresh state are sand tomortar ratio and water to powder ratio In concrete hardened state parameters as density compressive strength at age of 7 and 28days modulus of rupture and water absorption were studied as experiment s outputs Byevaluating contribution of each factor in the final results of compressive strength at the ageof 28 water to powder ratio with 51 7 was found the most and sand to mortar ratio with5 71 the least effective factors After conducting tests 0 27 m3 0 46 0 86 and 9 respectively the values of coarse aggregate sand to mortar ratio water to powder ratio andsilica fume replacement were selected as optimal levels of mixtures KeywordsConcrete lightweight Self Compacting Optimization Statistical Taguchi

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