Investigation on mechanical properties of composite concrete containing untreated sea sand and quarry dust for 100% replacement of fine aggregate

Abstract

Globally, concrete industry is using desalted sea sand as fine aggregate. The desalting process consumes huge quantities of fresh water and electricity, increasing the material cost. Quarry dust is a waste by-product from aggregate manufacturing units. Disposal of quarry dust creates huge havoc on environment and ecosystems. The present research is aimed to assess the feasibility of utilizing quarry dust and untreated sea sand as complete replacement for river sand. Prior to application, pH and chloride content in sea sand were determined. Mortar cube studies were performed to assess the feasibility of utilizing sea sand and quarry dust as replacement materials. Experimental investigations were performed by designing M30 grade concrete. Six concrete mixes (M1 to M6) were casted using river sand (M1-control mix) and blending untreated sea sand and quarry dust in varying percentages from 0 to 100% at a step interval of 25%. Workability parameters, slump height and vee-bee time were determined to assess the consistency of mixes. Uniaxial compression, split-tensile and flexural strength were determined on hardened concrete specimens. The microstructure morphology was investigated using scanning electron microscopic image analysis. The concrete mix M4 (50% sea sand + 50% quarry dust) is determined as optimum mix for complete replacement of river sand. The compressive strength of M4 mix is 38.7 ± 0.19 MPa. Increase in compressive strength with increase in amount quarry dust is observed. The split tensile of mix M4 is 3.8 ± 0.14 MPa and flexural strength is 3.5 ± 0.09 MPa. The outcomes of this study will enhance the potential application of untreated sea sand and quarry dust as an alternative construction material.