OPTIMIZATION OF FLY ASH IN CONCRETE: High Lime Fly Ash as a Replacement for Cement and Filler Material

摘要

This research paper seeks to optimize the benefits of using High Lime fly ash in concrete as areplacement for large proportions of cement.High Lime fly ash is a type of sub-bituminous fly ash that is self-cementing as well as pozzolanicin nature.High Lime fly ash would be categorized as a Class C fly ash by ASTM because of itshigh calcium content,however its sulfur content exceeds the limit set in ASTM C618.The physical and chemical properties of this type of fly ash,particularly its fineness and carboncontent properties(coarser particles and low carbon content),provide potential benefits.Thesetwo properties are of great concern since they will affect the air content and water demand of theconcrete;parameters that greatly affect the durability and strength of concrete.This paper describes early stages of a project to study the use of large volumes of High Lime flyash in concrete.During the project High Lime fly ash obtained from a local power plant will beused in the concrete tests.Varying amounts of fly ash will be used in given mixes of concrete asa partial replacement of the cement(binder)and fine aggregate(filler).Several design mixes willbe prepared,cured and tested for their compressive and bond strengths,and durability(freeze-thaw)properties.Each compressive strength sample will be tested at 3,7,14,28 and 56 days.The results will be analyzed and compared with standard concrete and conclusions made on howbest the fly ash can be utilized to give optimum results.The results presented in this paper address preliminary results for the compressive strength tests.The tests provided a general increase in the strength of concrete with addition of High Lime flyash.The test results indicate that replacing proportions of cement with High Lime fly ash wouldprovide improved strength and a most cost effective solution.