Corrosion and deterioration mechanism of water-rich filling materials in carbonate solutions

In order to research the impact of carbonate ions on water-rich filling materials,strength testing,scanning electron microscopy,X-ray diffraction analysis and IR spectrum testing were used to analyze the macro- and micro-structural change and the corrosion and deterioration mechanism of the materials in sodium carbonate solutions. It is found that the compressive strength of the materials in a sodium carbonate solution whose mass fraction is 10% decreases significantly with increasing soaking time. When the soak age is 90 d,the compressive strength of the materials decreases by 72.5% compared with standard curing for 28 d. After soaking for 28 d the specimen surface is muddy. XRD patterns show that after soaking in a sodium carbonate solution whose mass fraction is 10%,thaumasite generates in the materials. With increasing soaking time the amount of thaumasite increases. Infrared spectroscopy results show that there does not existAlO₆. This confirms that ettringite in the materials soaking in the sodium carbonate solution drastically reduces and transforms into pulpy thaumasite. As non-cemented materials,thaumasite will cause serious damage to the hardening body of the materials. This shows that the carbonate solution has corrosive action on water-rich filling materials.