Crushed Limestone Waste as Supplementary Cementing Material for High Strength Concrete

Abstract

Use of greener materials and gaining popularity of environment friendly materials worldwide has led to newer research in utilizing waste materials produced from various human, agricultural and industrial activities for useful purposes. Agricultural wastes like rice straw and husk, industrial wastes like slag, fly ash, crushed stone, limestone waste and brick/ concrete waste from demolition of old structures are extensively being used in manufacturing concrete. This experimental study aimed at evaluating the properties of widely produced waste material from limestone processing industry with no beneficial usage i.e. crushed limestone waste as supplementary cementing material. For years a small percentage of limestone powder has been used in cement and masonry to improve workability and in concrete as fine filler however limited research has been carried out on high strength concretes with partial replacement of limestone crush as supplementary material. This study investigated the properties of high strength concrete made from Portland slag cement comprising 50% cement and 50% ground granulated blast furnace slag, natural aggregates and sand where crushed limestone waste was added to cement by replacing slag cement in the percentages of 10% and 20%. Wide ranging investigations covering most aspects of mechanical behavior and permeability were carried out for various mixes for compressive strengths of 60MPa and 80MPa. Compressive strengths of concrete specimen with partial replacement of 10% and 20% limestone waste were observed to be higher by about 4 to 12% than the control specimen. Flexural strengths were also observed to be higher by 12 – 13%. Higher elastic moduli and reduced permeability were observed along with better sulphates and acid resistance. Better strengths and improved durability of such high strength concretes containing up to 20% limestone waste make it a more acceptable material for major construction projects in addition to consuming this massively produced waste material for useful purposes along with reducing its disposal problems.