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دراسة تاثير النانو سليكا المحضرة من رمال السيليكا العراقية على بعض الخواص الميكانيكية لمتراكبات الكونكريت == Study The Effect of Nano - Silica Prepared From Iraqi Silica Sand On Some Mechanical Properties of Concrete Composites
Author name:
علي داود سلمان
Supervisor name:
نجاة جمعة صالح
General topic:
Chemical Engineering
Specific topic:
Chemical Processes
Degree:
Master
University:
University of Technology - Department Of Chemical Engineering - Chemical Process Engineering Branch
Language:
English
University location:
Baghdad
First pages:
38T297 - p.pdf
Abstract:
ان الهدف من هذا البحث هو تحضير دقائق السليكا النانوية من رمال السليكا العراقية من منجم ارضمة غرب العراق باستخدام طريقة الطحن المتعدد في (جهاز الطحن بالكرات)،حيث تم تشخيص دقائق السليكا بواسطة اجهزة التشخيص التالية SEM, AFM, PSA,FT - IR, XRD, XRF, BET,TEM. | The purposes of this work are to prepare, characterize silica nanoparticles for a first time from Ardma location at Anbar province in western Iraq by combination of top down approach using ultrafine grinding (Ball milling) and drying processes, evaluate the effect of nano - silica sand (NSS) addition on mechanical properties (compressive and splitting tensile strengths) of mortar mixture, and optimization of the operating variables (NS particle size and percentage of (NS) by using [WinQSB] and [STATISTICA] software technique to find the optimum values. (XRF) test shows enrichment of SiO2 after leaching with sulfuric acid. The prepared (NS) is characterized by SEM, AFM, PSA, FT - IR, XRD, XRF, BET and TEM. According to Particle Size Analyzers (PSA) silica sand has successfully been reduced to particle size of 50 nm after (30) hours of milling. The (AFM) test reveal two different groups of samples were analyzed, the range of first group was (60 - 120) nm after 40 hours of milling, the range of second group was (90 - 170)nm after 50 hours of milling. X - ray diffraction of silica sand before and after milling process shows that surface , structural changes duo to amorphization phenomenon result from an intensive mechanical treatment by (Ball milling) of silica sand. This result supports the incorporating (NS) into cement mortar. The (BET) analysis shows that the (NS) has different surface areas according to particle size. The (TEM) and (SEM) images of NS show that various shapes of the(NS) particles including irregular, spherical, and highly agglomerated in shape due to Van der Walls force on the particles surface. Three different ranges of particle sizes of (NS) have been used; (30 - 100)nm,(60 - 120)nm and(90 - 170)nm with three percentages of each (2% ,6% and 10% per weight of cement) and a w/c of 0.48. The SEM images of mortar mixture at the age of 28 days show existence of many Ca(OH)2 crystals needles over - shadowed and cover a large area with porous structure, while after adding (NSS) the Ca(OH)2needles are invisible and compact structure with the absence of the un - hydrated crystals which explains the superior strengths results. NSS contributes to enhancement of cement mortar through yielding denser, more compact and uniform mixtures. The optimization results of mechanical properties proved that an improvement in compressive strength of 29.889% at optimum conditions (adding 6% of 50nm particle size) in 28 days age, while for tensile strength was 22.863% at optimum conditions (adding 8% of 50nm particle size) in 28 days age. NSS obtained by ball milling of silica sand can be produced in large quantities at low prices, by sustainable method so that mass application in concrete is within reach According to my knowledge there is no previous work focusing on preparing of silica nanoparticles from Iraqi silica sand, and using it to improve mechanical properties of cement mortar by using optimization technique.
