Abstract. A new dipping basalt fiber reinforced concrete (DBF-RC) was developed in this study. The surface of fiber was modified by dipping into epoxy resin. The mix of DBF was first researched on cement mortar, and then on concrete. The workability and mechanical properties of cementitious materials were investigated. Experimental results show that the optimum proportion of DBF is 1%, and with this mix, the compressive strength, flexural strength and flexural toughness of concrete can be improved effectively.
The mechanism and behavior of concrete carbonation have been researched in this study. Effects of cement quantity, water to binder ratio (w/b) and content of fly ash on carbonation reaction were investigated. Morphology, microhardness and carbonation depth were analyzed. Experimental results show that high quantity of cement, low w/b ratio and small addition of fly ash are beneficial to improve the anti-carbonation of concrete. INTRODUCTIONSteel corrosion is a widespread degradation mechanism in reinforced concrete structures.Carbonation results a decrease in pH of the surrounding concrete, from a high alkaline environment (pH about 13) to below 9, and thus destroys the passivation layer to generate corrosion of steel.As a main source of the strength of concrete C-S-H gel plays an important role in cement paste or concrete. However, carbonation of concrete is harmful to the performance of C-S-H gel.When carbonation happens, the C-S-H gel decomposes and produces CaCO 3 . This will significantly decrease the strength and pH of concrete, thus leading to the acceleration of steel corrosion and thus decrease durability of the structure.Concrete carbonation is the reaction between acidic CO 2 from air and alkaline phases of concrete. This will reduce the alkalinity and change chemical compositions of concrete. In fact, carbonation is a complex physical and chemical process. As is well-known, concrete is a porous solid, which consists of pores, bubbles, capillaries, and defects. The CO 2 can permeate into these porous structures, and contacts with alkaline substances to generate carbonation reaction.Alkaline phases produced from the hydration of cement mainly consists of calcium hydroxide
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