Effects of Ultra-fine Material on Workability, Particle Packing Density and Compressive Strength of Mortar

Abstract

Production of one tonne of cement releases almost equivalent amount of greenhouse gases like carbon dioxide into the atmosphere. In addition, cement production consumes natural resources as raw material. These activities cause tremendous load on the environment. Hence, by using lesser ordinary Portland cement in mortar and concrete will help reduce carbon di oxide emission in the atmosphere. Use of supplementary cementitious material as partial replacement of OPC is an ecological and environmentally friendly solution in concrete production. The use of industrial by-products or waste products as a partial replacement of ordinary Portland cement in mortar and concrete without compromising their engineering properties is a welcome move. The most widely used industrial waste products are fly ash (FA) which is obtained from thermal power plants and the ground granulated blast furnace slag (GGBS) which is by-product of iron manufacturing plants using in blast furnaces. This paper presents use of ultra-fine fly ash (UFFA) and ultra-fine slag (UFS) in cement mortars as partial replacement for the ordinary Portland cement. The properties of mortar such as particle packing density, workability in terms of flow value and strength properties such as compressive strength at early & late ages is studied. The mortars were prepared using binary combination of UFFA + OPC and UFS + OPC by replacing OPC with 5%, 10%, 15% and 20 % UFFS and UFS by OPC mass. Experimental results reveal that the replacement percentage of 15% and/or 20% of UFFA and UFS show values of compressive strength higher than or equal to that of control OPC mortar without any replacement. Pattern of workability corresponding to increment in replacement percentage of ultra-fine material in terms of flow diameter differ for both the ultra-fine materials.KeywordsCement mortarFly ashSlagUltra-fine materialPacking density