Abstract
Recent studies have shown promising potential for using Glass Pozzolan (GP) as an alternative supplementary cementitious material (SCM) due to the scarcity of fly ash and slag in the United States. However, comprehensive studies on the freeze–thaw (FT) resistance and air void system of mixtures containing GP are lacking. Therefore, this study aimed to evaluate GP’s effect on FT resistance and characterize mixtures with different GP contents, both macro- and microscopically. In this study, six concrete mixes were considered: Three mixes with 20%, 30% and 40% GP as cement replacements and two other comparable mixes with 30% fly ash and 40% slag, as well as a mix with 100% Ordinary Portland cement (OPC) as a reference. Concrete samples were prepared, cured and tested according to the ASTM standards for accelerated FT resistance for 1000 cycles and corresponding dynamic modulus of elasticity (Ed). All the samples showed minimal deterioration and scaling and high F/T resistance with a durability factor of over 90%. The relationships among FT resistance parameters, air-pressured method measurements of fresh concretes and air void analysis parameters of hardened concretes were examined in this study. X-ray micro-tomography (micro-CT scan) was used to evaluate micro-cracks development after 1000 freeze–thaw cycles and to determine spatial parameters of air voids in the concretes. Pore structure properties obtained from mercury intrusion porosimetry (MIP) and N2 adsorption method showed refined pore structure for higher cement replacement with GP, indicating more gel formation (C-S-H) which was verified by thermogravimetric analysis (TGA).
Highlights
The improvement of durability properties of concrete materials deserves special attention in order to extend the service life of structures
The findings in this study provide a multiscale understanding of durability properties of concrete with Glass Pozzolan (GP) as supplementary cementitious material (SCM), and the results contribute to practical implementations in cold environments
In this study we investigated the freeze–thaw (FT) resistance of concretes containing cement replacement by GP of up to 40% by weight, and comparing the performance with other commonly used SCMs
Summary
The improvement of durability properties of concrete materials deserves special attention in order to extend the service life of structures. Concrete structures are exposed to environmental effects as well (e.g., low-temperature weather conditions) and they can be harmful for porous brittle materials such as concrete. When concrete is subjected to repetitive freezing and thawing (FT) cycles, its durability is affected, leading to accelerated deterioration and loss of stiffness and strength. Freezing and thawing resistance is an essential durability property of concrete in cold weather environments. The water starts to freeze in capillary pores at temperatures well below the freezing point. Considering the freeze–thaw phenomenon, the most important factor in air void properties is pore interconnectivity
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