Performance of concrete containing granulated blast furnace slag as a fine aggregate

Abstract

The present challenge in front of Civil Engineers is to find alternative materials for fine aggregates in concrete. Since, most of the State Govt. banned the dredging of river sand. The Granulated blast furnace slag is considered as a fine aggregate in concrete. At present, in India Steel Industry produces about 40 Million Tonnes by 2020 it is estimated to 60 million tonnes. The Author has investigated the effect of compressive strength of concrete, when Granulated blast furnace slag is used (GBFS) as a fine aggregate in concrete. The work includes the partially and fully replacement of river sand by granulated slag in M25 Grade of concrete with a constant 0.45 W/C ratio. Slag replacement of 50, 80, 100% are used. It has been observed that concrete made with 50% of river sand and 50% (GBFS) is nearer to Zero percent replacement. Objectives: To determine the optimum percentage slag replacement as a fine aggregate in concrete which helps in maintaining sustainability of concrete and balancing between the environmental problems due to construction industry as it is necessary to find out the alternative materials for use as fine aggregates because of restrictions by the local authorities. Methods: The experiments are planned to find out the optimum replacement percentage of GBFS against river sand as a fine aggregate in concrete. Mix design for M25 grade of concrete is made with OPC (Ordinary Portland Cement) and PPC (Port land Pozzolana Cement) is considered with a constant 0.45 W/C ratio and slag replacement of 50, 80, 100% are used. 30 Cubes for each cement category of 150 mm size are casted, cured by immersion and tested by CTM. Findings: In both the cement category, the compressive strength and slump of concrete is found reducing with the increase in the percentage of slag as a replacement to fine aggregate. In concrete made with OPC when compared with 50%, 80% and 100% replacement with GBFS reduction upto 96.50%, 87% and 77.5% in strength and 84.6%, 53.84% and 34.6% in slump respectively is observed. In concrete made with PPC when compared with 50%, 80% and 100% replacement with GBFS reduction upto 95.30%, 80% and 63% in strength and 82.7%, 51.7% and 34.0% in slump respectively is observed. Application/Improvements: This study using alternatives to fine aggregate in concrete will help in making concrete economical, reduction in environmental problems and saving the natural resources. The study may be extended to determine the concrete sustainability in saline conditions also.