Evaluation of the Compressive Strength and Rapid Chloride Permeability of High Replacement Ternary Mixtures

摘要

Portland cement concrete (PCC) is the world’s most versatile and most used constructionmaterial. To meet the global demand for sustainability, engineers have looked to alternativesupplementary cementitious materials (SCMs) such as fly ash, silica fume, ground granulatedblast furnace slag, to increase pavement durability while lowering the initial and life-cycle cost.The objective of the study was to characterize the fresh and hardened concrete characteristics ofhigh volume ternary cementitious combinations. Twenty-seven ternary mixtures with portlandcement replacement rates ranging from 50 to 90 percent were produced and the fresh andhardened characteristics were determined. Fresh concrete properties of air content, slump, unitweight, and set time were measured. Hardened concrete properties measured includedcompressive strength at 7, 14, 28, 56, and 90 days of age and rapid chloride permeability at 56days of age. Compressive strength results showed equal to or greater compressive strengthsespecially at later ages of 56 and 90 days. The compressive strengths of all mixtures with SCMreplacements up to 80 percent meet Louisiana Department of Transportation and Development(LADOTD) specifications of 4000 psi at 28-days. The ratios of the seven to 28 day compressivestrengths showed that they are more resistant to early age cracking due to the lower modulus atearly ages allowing for more creep. The rapid chloride permeability results show that the ternarymixtures will easily meet the new permeability specifications for all structural class concreterequiring less than 1500 Coulombs at 56 days. Results of this study indicated that a replacementlevel of up to 70 percent SCMs are reasonable for LADOTD construction projects.