الفهرس 
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Abstract
The main objective of this research is to investigate the efficiency of different water proofing coatings, admixtures and additives on reducing concrete permeability. The research work was divided into two sections. The first section deals with the six types of waterproofing coating in the Egyptian market, whereas the second section discusses the different waterproofing admixtures and additives. The waterproofing coatings which have been studied were cement polymer modified, cement acrylic modified, crystallization coating, siloxane base, epoxy base and bituminous base coating. All the used waterproofing coatings were coated to two concrete mixes (Grade 30 MPa and Grade 40 MPa). The waterproofing admixtures and additives used were Type A admixture, high range water reducer, latex (SBR), silica fume and two types of crystallization admixtures from two suppliers. All the used waterproofing coatings were tested in water penetration depth, absorption and adhesion to concrete, while additional tests were performed to the used admixtures and additives percentage of permeable voids and compressive strength. Coating material application to hardened concrete significantly decreased permeability of concrete specimens. Moreover, the properties of concrete and their constituents were found to be important when evaluating the effect of coating materials. Test results of waterproofing coatings showed that the epoxy base coating is the best waterproofing coat, while the cement acrylic modified coating is the most economic coating comparing to other used coats in the study. The bituminous coating yields the worst results at all the tests. Test results of waterproofing admixtures and additives showed that the water cement ratio is the most important factor to achieve low permeability concrete.the crystallization admixture achieves the best results at 28 days while Type A admixtures have a little effect on concrete properties.