الفهرس 
INTRODUCTION AND RESEARCH SIGNIFICANCEOnly 14 pages are availabe for public view
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Abstract
This research concerned with using nano-materials in high strength concrete (HSC),high-performance concrete (HPC) and ultra-high performance concrete (UHPC). Three phases werestudied. The first phase concerned with studying the effect of using different dosages of nano-silica(NS) and nano-metakaolin (NMK) on the properties of HSC and different dosages ofNSon the properties ofHPC. The studied properties included compressive strength, flexural strength,absorption, porosity, drying shrinkage and durability of these concrete to magnesium sulfateattack, nitric acid attack and sulfuric acid attack. The variables included; (a) compressive strengthlevels of 55 MPa, 80 MPa and 90MPa (concrete grade), (b) type ofnano-material (NS andNMK) and (c) dosage of nano-material from cement weight. The second phase included studyingthe effect of using nano-materials to enhance the corrosion resistance of reinforcement steelbars embedded in concrete. Nano-materials were used as additives to HSC mix (55 MPa concrete grade). Also, nano-materials were used as rebar steel coating materials. Nanomaterialsincluded NS or NMK. These materials were added to zinc rich or epoxy resin coating withdifferent dosages. The effect of using cement with these materials was studied also.Corrosion rate was evaluated thoroughly using polarization technique. The third phase concernedwith the production and studying the properties ofUHPC with compressive strength from135 MPa to 155 MPa using NS as an additive material. The studied properties included compressivestrength, flexural strength, absorption, porosity, drying shrinkage and durability ofthese concrete to sulfuric acid attack. The studied variable was the dosage ofnano-material NS)from cement weight. Production of this concrete was carried out using the local fine sand,cement,silica fume, superplasticizer and imported high-tensile steel fibers of 0.20 mm diameter andlength of 13 mm. Steam curing for 3 days was used.This research yielded many conclusions, for example; First phase: The use ofNS as an additivein range of 0.5% to 2.0%, and NMK, in range of l.0% to 9.0%, has a positive effect onreducing water capillary absorption and total porosity for different studied concrete grade levels.The positive effect of used nano-materials decreases with the increase of concrete grade levels.Adding NS or NMK to HSC, also adding NS to HPC enhances the magnesium sulfate resistance.In terms of compressive strength loss, the use of 2.0% NS with 55MPa concrete gradeyields 18.6% reduction in concrete compressive strength loss after 360 days of 10%magnesium sulfate exposure, while the use of 9.0% NMK yields 4l.4% reduction incompressivestrength loss, compared with that of concrete without nano-materials. The increase ofconcrete grade improves the acid resistance of concrete for concrete with and without nano materials. This enhancement is more significant in case of nitric acid than sulfuric acid. Based on compressive strength loss and concrete materials cost ($lMPa), simplified cost analysis is presented. NS is preferred for different concrete grade levels of compressive strength loss (15%,20% and 25%). Where, the lowest cost per MPa corresponding to 15% compressive strength losscan be achieved using 0.5% NS while 1.5% NS yields the lowest cost per MPa in case of 25% compressive strength loss. Second phase: the use of 0.5% NS as an additive slightly decreasesthe corrosion rate. The use of 1.0% and 2.0% NS as additives decreases the corrosion rates after 360 days by 13.8% and 28.7%, respectively. The use ofNMK as additives highly decrease the corrosion rate, as an example; the use of 1.0% and 6.0% of NMK decreases the corrosion rates by 26.1 % and 48.9%, respectively. Third phase: UHPC with 28 days compressive strength up to 155 MPa and modulus of rupture up to 23 MPa was produced using localmaterials and steam curing. The use of NS decreases the drying shrinkage of UHPC that contains a high cement content. The use of 2.0% NS decreases the 150 days drying shrinkage by 26.8% compared with concrete without NS. The use of2.0% NS as an additive improves the durability of UHPC subjected to sulfuric acid attack of pH = 1 specially with the increase of exposure period