الفهرس 
Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
As the increasing of the demand on a specific performance characteristics in concrete such as improved strength, low heat, sulfate resistance, improved impermeability and certain other applications, additives rather than used in ordinary Portland cement which have considerable scientific and technological interest are used. The present thesis contains three main chapters:- Chapter I: ”Introduction and literature review” This chapter represents an introduction and literature review concerned with Portland cement, blended cement, polymer definition, classification of polymer-based or polymeric admixtures, polymer modified mortar, radiation and finally sulfate attack on cement mortar. Chapter II: ”Materials and experimental techniques” This chapter represents materials and experimental techniques that were used in the preparation and characterization of blended cement mortar composites. It also includes a complete description of compressive strength test, Total porosity, water absorption, bulk density measurements, X-ray diffraction, Scanning electron microscope and Thermal gravimetric analysis. Chapter III: “Results and discussion” The results and discussion are divided into three parts and can be summarized as follow: III-1-Effect of nano-calcined clay (NCC) on physico-mechanical properties of cement mortar The results showed that, the compressive strength values of blended cement mortars are gradually increased with increasing nano-calcined clay (NCC) contents up to 5% and then decreased with more nano-calcined clay (NCC) content. The increase of compressive strength values with nanocalcined clay percentage from 2.5 to 5% is attributed to pozzolanic reaction. Bulk density values of blended cement mortars increase with increasing (NCC) content up to certain values and then gradually decrease. Total porosity and water absorption percentages have an opposite direction. XRD and SEM observations confirmed that, pozzolanic reaction between Ca(OH)2 liberated during hydration process and alumino-silicate element in nano-calcined clay leads to the addition in the bond strength in the blended cement mortar specimens. III-2- Effect of γ-irradiation on the properties of polymer–nanocalcined clay cement mortar composites III-2-1- Styrene Acrylic Ester (SAE) Latex The compressive strength and bulk density of SAE-NCC-cement mortar composites increase with increasing P/C ratio and γ-irradiation dose up to certain values and then gradually decrease. Total porosity and water absorption percentages have an opposite direction. TGA, XRD and SEM studies indicated interactions between some of SAE polymer molecules and hydrated cement and NCC particles. Also, SAE polymer modified the microstructure of the hydration products of blended cement and form a dense matrix. III-2-2- Poly vinyl alcohol (PVA) Compressive strength and bulk density of PVA-NCC-cement mortar samples increase with increasing the absorbed dose and PVA content at certain values and then decrease with a higher irradiation dose and PVA content. Compressive strength and bulk density of irradiated composites are higher than that of blank specimens prepared under the same conditions. Total porosity and water absorption percentages decrease with increasing the absorbed irradiation dose as well as PVA content, also its values are higher as compared to blank samples, these due to deposition of solid materials in the pore system of the composites. XRD, SEM and TGA observations confirmed that, chemical reactions between the composite components took place with application of γ-irradiation. III-3- Magnesium sulfate attack The results show that a relative increasing in the compressive strength values for all the specimens soaked in tap water with increasing of immersion time, while the values of compressive strength for both control and modified mortar samples soaked in MgSO4 slightly decreased with the increasing of immersion time as well as magnesium sulfate concentrations. The improvements in compressive strength of all samples soaked in tap water are due to hydration process of unhydrated blended cement and the decreasing in compressive strength values of all specimens soaked in MgSO4 (0.5 and 3%) are essentially dependent on the chemical reactions between hydrated blended cement and MgSO4. The greatest resistance against MgSO4 attack in order as follows: SAE-NCC-cement mortar > PVA-NCC-cement mortar > NCC-cement mortar.