Durability And Sustainability Of Fly Ash Hpc Exposed To Freeze-Thaw Cycles

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Title: Durability And Sustainability Of Fly Ash Hpc Exposed To Freeze-Thaw Cycles

Author(s): Alessandro Pasqualini; Marco Bressan; Felice Marco Liberatore

Publication: Special Publication

Volume: 305

Issue:

Appears on pages(s): 20.1-20.8

Keywords: durability, fly ash; freeze-thaw cycles; HPC; sorptivity, strength, sustainability

Date: 9/1/2015

Abstract:
The concrete exposed to freeze-thaw cycles, with or without deicing salts presence, can suffer extensive damage on the cement matrix with a direct impact on the structures durability. The prescriptions to be adopted for preventing this concrete deterioration are described in the European Standard EN 206-1. This standard provides specific exposure classes for Concrete Structures exposed to freeze-thaw cycles (XF) and, for each of them, a series of requirements to ensure the necessary durability. Among these requirements there is the adoption of a minimum volume of entrained air, which avoids the excessive development of internal stresses due to ice formation in the cement matrix. The introduction of air significantly reduces the concrete’s mechanical performance. To take account of this aspect, the mix design must be modified with a higher content of cement to restore the final compressive strength. This aspect becomes more penalizing and not much sustainable for high performance concretes (HPC). The aim of the work is to propose a sustainable use of fly ash in concretes, compatible with the XF exposure classes defined in the European Standard. The solution allows to restrict the cement content to the minimum values required, with technological, economic, and environmental benefits, due to using a by-product from coal combustion power plant.