Sustainable Construction - Investigations on Use of Waste Limestone Dust as Filler in High Performance Concrete

摘要

Massive amounts of limestone waste is produced by the stone processing industry worldwide. Generally, it is believed that 60% to 70% of the stone is wasted in processing in the form of fragments, powder and slurry out of which around 30% is in the form of fine powder [1]. This waste has no beneficial usage and poses environmental hazards. Use of this waste product in the construction industry can largely reduce the amount of waste to be disposed off by the local municipalities in addition to reducing large burden on the environment. Some basic research on use of limestone dust as cement/concrete filler has been carried out in the recent past but high strength/high performance concretes have not been investigated yet [2-5]. The concrete industry worldwide is among the largest consumer of raw materials and has been investigated for use of various types of waste materials like crushed brick, rice husk and straw ash as either aggregates for concrete or as partial cement substitutes [6-11]. Use of waste limestone dust as filler material in concrete can consume a huge amount of this waste material which has to be disposed off otherwise, creating large burden on the environment. This experimental study aimed at evaluating the properties of high performance concretes made from Portland cement, natural aggregates and sand. Waste limestone dust was added by replacing sand 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 60N/mm~2, 80N/mm~2 and 100N/mm~2. Compressive strengths of concrete specimen with partial replacement of sand with 10% and 20% limestone dust as filler material for 60N/mm~2, 80N/mm~2 and 100N/mm~2 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 sulphate and acid resistance. Better strengths and improved durability of such high-performance concretes make it a more acceptable material for major construction projects.