الفهرس 
CH APTER 1Only 14 pages are availabe for public view
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Abstract
Hydrophobic materials , such as long chain fatty acids , paraffin wax , mineral oils , vegetable oils and bitwnens are used as water repelling admixtures for concrete to decrease the water absorption under low hydrostatic pressures . Therefore , the aim of this investigation is to clearify the effect of such
t’ materials on the compressive strength , hydration kinetics , bulk density , porosity , water absorption , phase composition , microstructure and surface properties of the hardened Portland cement pastes .
Different hydrophobic materials were used in this investigation , namely , stearic acid, palmetic acid and vegetable oil Portland cement pastes were prepared using different ratios of the admixtures (0,0.25, 0.45, 0.75 and 1.5% by weight of dry cement ) and water I cement (W/C) ratio of
0.30 . In case of mortar , the results with palmetic acid as an admixture are reported as representative results for the effect of these materials . The admixture ratio used in case of mortar were 0.45, 1.5 and 2.5% by weight of the dry cement. Curing was carried out for various ages , namely ; I ,3,7 and 28 days .