Studies on Long Term Performance of Concrete Using Dredged Marine Sand

Abstract

Nowadays concrete is most importantly used material in almost all structures as a basic material. The sand which is taken generally from quarries or alluvial rivers is a basic ingredient for manufacturing the concrete. But this source of sand is in a state of depletion and their further extraction may cause harmful effects on environment. To counteract this problem some other sources have to be found out and studied as well as experimented. Some of the alternates are dredged marine sand, offshore sand, dune sand, quarry dust and washed soil which also have to be used for replacing the fine aggregate. Thus the use of natural river sand in concrete is to be minimized and saving the natural resource of river is to be made. Two concrete grades are used in the concrete i.e. M25 and M40. Two types of cements are used in the concrete i.e. OPC and PPC. Three different concrete mixes are taken in to consideration for the experiment i.e. Mix-A (concrete made using 100% natural river sand), Mix-B (concrete made using 50% replacement of natural river sand with dredged marine sand) and Mix-C (concrete made using 100% replacement of natural river sand with dredged marine sand.) The project mainly concentrates on the use of Dredged Marine Sand (DMS) as a fine aggregate during casting of concrete and evaluating its effectiveness through mechanical properties like compressive strength & Durability properties. Sulfate, Acid and Chloride exposure , Sorptivity, Water absorption for plain concrete cubes and Accelerated corrosion test for Reinforced concrete cylinders. Standard size concrete cubes are cast as per IS provisions. Change in the appearance and change in mass after exposures in all chemicals are observed and studied for durability properties. Also the non-destructive testing is performed for the concrete specimens. The results related to mechanical and durability properties for all concrete mixes have suggested adequate performance of concrete made with dredged marine sand as compared to the concrete with natural river sand. Mechanical properties of concrete made with dredged marine sand indicate higher results for concrete Mix-C made with 100% dredged marine sand as compared to that of concrete Mix-B made with 50% replacement of river sand with dredged marine sand and concrete Mix-A made using 100% natural river sand at the end of 56 days curing. Durability properties like acid and sulfate resistance of concrete made with dredged marine sand show better performance for concrete Mix-C made with 100% dredged marine sand as compared to that of concrete Mix-A made using 100% natural river sand and concrete Mix-B made with 50% replacement of river sand with dredged marine sand after completion of 3 months of exposure in acid and sulfate solution, respectively. Chloride resistance test suggests that concrete made with dredged marine sand show less resistance against chloride solution for 2 months of exposure to presence of chloride in dredged marine sand. Sorptivity and water absorption test indicate almost similar results for concrete made with dredged marine sand as compared to that with natural river sand. Concrete Mix-C made with 100% dredged marine sand shows better resistance against the corrosion as compared to concrete Mix-A made using 100% natural river sand and concrete Mix-B made with 50% replacement of river sand with dredged marine sand. Investigation suggests successful use of dredged marine sand in concrete as a fine aggregate in construction activities. Furthermore investigation is to be done related to the chloride resistance of concrete with dredged marine sand.