EFFECT OF CORROSION ON DURABILITY OF MINERAL FREE DREDGED MARINE SAND CONTAINING MORTAR WITH VARIOUS ADDITIVES

摘要

The quality of cement mortar(CM) used to plaster on the concrete surface has great influence in preventing the corrosion of reinforcement in reinforced cement concrete structures(RCC), especially in onshore or offshore construction. The depletion of natural sources for sand makes it imperative to search for alternative materials for fine aggregate. Utilization of alternative materials from marine sources, especially for offshore and onshore structures would be an acceptable solution. In this paper, mechanical, rheological and durability properties of mortar used for covering the exposed RCC surfaces by partial replacement with mineral free dredged marine sand (MS) as 5%, 10%, 15%, 20% and 25%withcarbonated coconut shell ash (CA) of various percentages as 0.5, 1, 1.5, 2 and 2.5. The results revealed that while adding MS, the compressive strength is found decreasing, which has been enhanced by partial substitution of CA of various percentages, which has revealed enhancement in compressive strength up to 1.5% substitution. The mix with 1.5% CA has been taken for further analysis using tamarindus seed coat extract (TE) of 0.5%, 1%, 1.5% and 2% as a damp proofing and permeability reducing admixture and considerable increase in strength has been observed. Using all the same mixtures, in order to measure the corrosion resisting property, which is proportional to the durability properties like Electrical Resistivity and Ultrasonic Pulse Velocity (UPV), tests have been conducted in addition to the pull out test, after conducting accelerated corrosion test for the selected mixtures and significant improvement has been observed. Workability test including sieve analysis to find fineness modulus(FM)for each mix has been also conducted and exhibited satisfactory results.