Abstract
Alkali-silica reaction (ASR) widely occurs in concrete, resulting in durability problem and premature loss in serviceability of infrastructures all over the world. Understanding of the properties of ASR products, especially at micro scale level, helps mitigation of deterioration in concrete structures. In this study, the nano-scale structure and mechanical properties of the ASR products under dry and saturated conditions are investigated. The scanning electron microscope and energy dispersive spectrometer with X-ray (SEM-EDS) and atomic force microscope (AFM), as well as the nanoindentation are applied to the ASR products. The experimental observation indicates the effect of water on the micromorphology and nano-scale mechanical properties of ASR products. Water makes contribution to the transformation of ASR products from solid to viscous gels and the decrease in the Young’s modulus and hardness of ASR products. The testing results reveal the correlation between nano-scale structure and mechanical properties and improve the understanding of the micromechanical behavior of ASR products.
Highlights
Alkali-silica reaction (ASR)[1] is a chemical process where the OH- ions existing in the pore solution attack the amorphous and poorly crystalline silica in aggregates in concrete
This paper focuses on the influence of water on the nano-scale structure and mechanical properties of ASR products
The elemental composition of the ASR products is tested by EDS in separated testing points along the crack (Fig. 1)
Summary
Alkali-silica reaction (ASR)[1] is a chemical process where the OH- ions existing in the pore solution attack the amorphous and poorly crystalline silica in aggregates in concrete. Jun-Ho3 used SEM-EDS to study the development of mortar bars with glass aggregate and analyze the different cracks inside the glass particles. They found that the interior cracking was important for the development of the ASR products. The diffusion of ASR gels with absorbing water into the surrounding pores and microcracks depends on the microstructure of the ASR products Besides, the nano-scale mechanical properties of the ASR products affect the cracking of concrete due to ASR products swelling. It would be helpful to understand the ASR-induced deterioration mechanism if the effect of water on the microstructure and nano-scale mechanical properties of ASR products is identified. The nano-scale structure and mechanical properties of the ASR products are compared under saturated and dry conditions by the means of AFM and nanoindentation
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