بررسي كاربرد نانو سيليس بر دوام بتن در سازه هاي هيدروليكي

چكيده انگليسي :

112Application Nanosilica on Concrete Durability in Hydraulic Structures Meysam tavakolian m tavakolian@cv iut ac ir September 22 2013 Civil Engineering Department Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor Kiachehr behfarnia Email address akabiri@cc iut ac irSupervisor Abdoreza kabiri samani Email address kia@cc iut ac irAbstract Concrete is the most common material in construction of the hydraulic structures Dams and the related hydraulic structures are known as long servicing life structures Theirmaintenance costs are high thereby their durability is an important issue Concrete abrasion is oneof the most important factors in threatening the durability of hydraulic structures thus is consideredas a primary factor in determination of the servicing life of a hydraulic structure Concreteabrasion is generally caused by friction and impact of suspended particles such as sand gravel rock ice and debris Spillway aprons stilling basins sluiceways culverts and tunnels arevulnerable structures to the concrete abrasion Former studies have focused on improving themechanical properties of concrete using different additives and have reported success in theirconcrete design mixtures Recently among different additives investigators increasingly noticethe nano additives For this purpose part of the cement in mixture is replaced by nano materials Former results indicate that nano particles improve the mechanical properties of concreteremarkably Present study focuses on investigating the effects of nano silica on durability of concrete inhydraulic structures Experimental study was perfomed on durability of ordinary and self compacting concrete SCC including abrasion resistance permeability and water absorptioncontaining nano solica According to the merits of SCC it is widely used in hydraulic structuressuch as dams spillways and tunnels thus this was the main motivation to apply nano silica in SCCas the major focus of the present study Based on the results the effects of nano particles onmechanical and durability aspects of ordinary and self compacting concrete were compared Consequently the optimal amount of silica nano particles in design mixture for both ordinary andself compacting concrete was obtained To achieve a proper concrete mixture the time and technique of the mixing materials in SCCespecially by adding the nano particles are important issues Adding nano silica into the mixture ofwater and superplasticizer as well as using high shear disperse mixers lead to a homogeneousmixture of nano silica in concrete ordinary concrete and SCC Results of fresh phase concretetests indicated that viscosity and shear stress increased Thus the workability and bleeding of theconcrete mixture decreased Mechanical and physical characteristics of the concrete specimensincluding compressive strength abrasion resistance permeability and water absorption improvedby means of adding a low percentage of silica nano particles significantly However greater valuesof nano silica weakened the concrete expected properties Negative effects of excessive magnitudsof silica nano particles in self compacting concrete were more evident compared to the ordinaryconcrete The results of compressive strength tests have a logical correlation with the results ofabrasion resistance tests Therefore a second order polynomial correlation was developed betweenthe 28 day compressive strength and abrasion resistance of concrete Keyword Durability Hydraulic structures Nano silica Self compacting concrete Abrasionresistance Permeability Water absorption

توكليان، ميثم

بررسي كاربرد نانو سيليس بر دوام بتن در سازه هاي هيدروليكي

بتن خود متراكم , مقاومت سايشي , نفوذپذيري , جذب آب , دوام