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Durability and long-term performance of concrete exposed to deleterious ions and environmental conditions are major concerns. The rapid chloride permeability (RCP) test is commonly used in specifications in the United States to evaluate the permeability of concrete. To evaluate the critical factors that control the service life of structures, the investigation of various concrete mixtures is required. In this paper, the performance of 54 concrete mixtures containing three types of water-reducing admixtures, two types of aggregates, and two levels of cement contents are evaluated in the RCP and freezing-and-thawing tests and the air void structure of selected mixtures are analyzed. It was found that the use of supplementary cementitious materials (SCMs) significantly enhances the performance of concrete mixtures in the RCP test. In addition, mixtures containing up to 30% of Class C fly ash and 50% slag content achieved exceptional durability performance in both RCP and freezing-and-thawing (F-T) tests. The "very-low"RCP values were foundfor mixtures containing Class Ffly ash and polycarboxylate ether (PCE) admixture.
Keywords: air void analysis; chemical admixtures; durability; freezing and thawing (F-T); rapid chloride permeability (RCP); supplementary cementitious materials (SCMs).
INTRODUCTION
The durability and long-term performance of concrete exposed to deleterious solutions and environmental conditions are major concerns.1 Increased demands for rapid concrete construction have given rise to concrete durability challenges, including corrosion of reinforcing steel, chemical attack from increased use of deicer salts, and resistance to freezing and thawing (F-T).1 The penetration of deleterious ions in concrete exposed to chloride-based deicing agents or marine environments is considered one of the major causes of deterioration of concrete. Such ingress of ions can result in corrosion of reinforcing steel and subsequent cracking, thereby accelerating the potential deterioration of concrete.2 The rapid chloride permeability (RCP) test is commonly used in standard specifications in the United States to evaluate the permeability of concrete to chloride ions.2 To achieve concrete with reduced chloride permeability and enhanced corrosion resistance, an investigation of various concrete mixture designs, proportions, and durability performances is required.3 While considerable literature of fragmented studies exists on durability of concrete (especially with respect to widely used F-T and RCP tests),4-14 there are limited research reports that encompass the evaluation of concrete mixtures with a variety of supplementary cementitious materials (SCMs), chemical admixtures, aggregate...