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Deterioration of concrete structures due to reinforcement corrosion because of chloride ingress is a growing problem in many countries throughout the world. Partial replacement of portland cement by mineral additions, such as ground granulated blast furnace (GGBS), silica fume and fly ash influences the resistance of the pastes and mortars to the chloride environments. The rate of chloride ingress into mortar depends on the pore structure and the capacity of the hydration products to bind chlorides This paper reports the comparative results of mechanical and permeability properties of blended mortars. Mortar specimens were made with slag replacement levels of 60%, 70%, and 80%, fly ash replacement levels of 20%, 30%, 40%, and 50% and silica fume replacement levels of 5%, 10%, 15%, and 20%. The following tests were performed: compressive strength, water absorption, rapid chloride permeability, mercury intrusion porosimetry, and X-ray diffraction. Mortars with fly ash and slag reported lower strengths than silica fume mortars. The silica fume mortars show a 50% pore size of that for the mortar without addition. The densifying effect of these materials on the microstructure is attributed to the sealing of pore openings and the narrowing of pore channels by the hydration products of pozzolanic reactions. This results in a reduction in permeability. In general, the use of these admixtures improves the resistance of portland cement mortars against chloride attack. The slag added mortar obtained the best performance.

Concrete is a brittle material with a relatively low tensile strength compared to its compressive strength. Reinforcement with randomly distributed short fibers could improve the ductility and tensile strength of concrete and permits the stabilization of the crack system. These products could be used in marine applications, but several chemical reactions must be controlled to generate durable materials. Sulfates and chlorides presented in seawater are especially dangerous ions for the concrete and the reinforcing steel. The main objective of this research was to determine the effects of a marine environment on the properties of fiber reinforced mortars. Different types of natural and synthetic fibers such as sisal (S), fique (F), coconut (C), glass (G), polypropylene (PP) and steel (St) were used. The physical, mechanical and durability properties of the mortar made with each type of fiber were determined. The mortar matrix included additions such as silica fume (SF), and a superplasticizer (SP). Durability properties under marine environments were evaluated by measuring chloride ion penetration and water absorption. The test results indicate an increase in the matrix porosity due to fiber application, but the blended cement matrix showed superior performance compared to the portland cement under marine service conditions. The utilization of mineral additions and additives in fiber reinforced mortars under severe environments was recommended.

An alkali-activated binary mortar (AABM) was studied as a possible alternative to traditional surface protection systems (coatings) or repair materials. A natural volcanic pozzolan (70%) and a granulated blast furnace slag (30%) were employed as precursors. According to standard specifications (EN 1504-3) and the properties of AABM the material was classified as a class R2-repair mortar.  Index Terms-natural volcanic pozzolan,  alkali-activated mortar, coating mortar, repair mortar