Alkali-silica reaction and microstructure of concrete subjected to combined chemical and physical exposure conditions

Daria Jóźwiak-Niedźwiedzka,Aneta Antolik,Karolina Gibas,Mariusz Dąbrowski,Michał A Glinicki,I Hager,T Tracz

doi:10.1051/matecconf/201816305009

Daria Jóźwiak-Niedźwiedzka, Aneta Antolik + Show 5 more

Open Access

https://doi.org/10.1051/matecconf/201816305009

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Abstract

Salt solutions are used to ensure safe driving conditions during winter. NaCl deicer is the most often used brine in Polish climatic zone. The chemical effects of this type of chloride-based deicer in wetting and drying (WD) and temperature cycles on concrete need to be better understood. This research was focus to study the microstructure of air-entrained pavement concrete after combined chemical (10% of NaCl) and physical (WD and 60°C) exposure conditions. The adopted WD and temperature regime was designed to verify the hypothesis that regularly alternating wetting and drying cycles with external alkali supply from deicer salt will provoke the Alkali-Silica Reaction (ASR). The aggregates varied their origin and mineralogical composition. The microscopic examination was carried out on concrete specimens using SEM with EDX. The microscopic analysis has shown that main reason for concrete deterioration during cyclic chemical and physical exposure conditions was both physical influence - WD cycles and the chemical influence – ASR (primarily, the fine aggregate which lead to form of alkali-silica gel). The expansive gel was shown to be capable of destroying the test specimens. Also differences in mineralogical composition of coarse aggregates influenced on the concrete prism expansion due to ASR.

Highlights

In central, eastern and northern Europe, and in the north America the climatic conditions in the autumn and winter season are severe for concrete construction and concrete infrastructure
The safe driving conditions during winter months are of primary concern, large quantities of deicing chemicals are applied in order to clear the pavement and to allow for the normal traffic flow, [1]
The visual inspection revealed that almost all concrete specimens showed the crack network on the surface, the single pop-out or the beginning of the surface scaling of the edges were observed for specimens with aggregate from glacial deposits (Gr), Fig. 1

Summary

Introduction

Eastern and northern Europe, and in the north America the climatic conditions in the autumn and winter season are severe for concrete construction and concrete infrastructure. The successive wetting/drying (WD) and freezing/thawing (FT) cycles cause both external and internal concrete deterioration. The outdoor structures may (in certain cases) be exposed to over 100 cycles. The exposure conditions become even more severe in the urban and suburban areas located in cold regions as a result of heavy use of deicing salts. The safe driving conditions during winter months are of primary concern, large quantities of deicing chemicals are applied in order to clear the pavement and to allow for the normal traffic flow, [1]. Highway deicers often contain chlorides as freezing-

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