Abstract
This paper experimentally studies the effects of fly ash on the diffusion, bonding, and micro-properties of chloride penetration in concrete in a water soaking environment based on the natural diffusion law. Different fly ash replacement ratio of cement in normal concrete was investigated. The effect of fly ash on chloride transportation, diffusion, coefficient, free chloride content, and binding chloride content were quantified, and the concrete porosity and microstructure were also reported through mercury intrusion perimetry and scanning electron microscopy, respectively. It was concluded from the test results that fly ash particles and hydration products (filling and pozzolanic effects) led to the densification of microstructures in concrete. The addition of fly ash greatly reduced the deposition of chloride ions. The chloride ion diffusion coefficient considerably decreased with increasing fly ash replacement, and fly ash benefits the binding of chloride in concrete. Additionally, a new equation is proposed to predict chloride binding capacity based on the test results.
Highlights
Since Portland cement was invented in 1824, cement has become the most important and irreplaceable building material in infrastructure construction
There are very few references on the distribution of chloride ions in concrete soaked with seawater, indicating the demand for a comprehensive study that covers the micro-properties and transportation mechanism and the chloride binding capacity of fly ash concrete
The free and total chloride contents were determined in accordance with the AASHTO T260
Summary
Since Portland cement was invented in 1824, cement has become the most important and irreplaceable building material in infrastructure construction. It has been reported that, per ton, replacing Portland cement by fly ash can reduce one ton of carbon dioxide emissions [11]. Due to filling and pozzolanic effects [31,32,33], adopting fly ash to partly replace cement can increase chloride ion resistance and lead to the better durability of concrete [34,35,36]. There are very few references on the distribution of chloride ions in concrete soaked with seawater, indicating the demand for a comprehensive study that covers the micro-properties and transportation mechanism and the chloride binding capacity of fly ash concrete. The current investigation aimed to systematically examine the effect of fly ash on chloride ion diffusion in concrete in a water soaking environment. Through a mercury intrusion method and SEM, the study explored the effects of fly ash on the pore structure and cement hydration products
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