Research is under way to study the strength and durability of concrete in Florida. Results of the first phase of this research are presented. Twenty-two concrete mixtures were prepared and tested for compressive strength, water permeability, chloride permeability (AASHTO T277), and corrosion resistance. Four groups of concrete mixtures that covered a wide range of materials and mixture proportions were included. Fly ash content ranged between 10 and 50 percent by weight of the total cementitious material. Silica fume was included in proportions between 5 and 15 percent. Effects of fly ash and silica fume on strength and permeability of concrete and on corrosion of steel in concrete are discussed. Correlation is established betwen results of the Florida water permeability test and results of the AASHTOT277 chloride permeability test. It is also shown that concrete mixtures with equal compressive strengths do not necessarily produce equal levels of permeability, especially when fly ash and silica fume are included in the mixture. Findings from this phase of the research affirm the need to develop specifications for concrete durability based on requirements for both compressive strength and permeabilityof concrete.
Abstract