Experimental Study of Sulfate Erosion Resistance of Cementitious Sand with Waste Glass Powder

In order to save natural resources and protect the natural environment, the relevant performance of waste glass powder as a building material must be enhanced. In general, volcanic ash activity is enhanced through grinding the glass powder particles to a specific degree of fineness, thereby improving the overall strength of cementitious sand. Our current need is to study the effects of replacing standard sand with glass powder of varying particle size and dosage range on its resistance to sulfate erosion as well as the corresponding mechanisms. To further examine the durability properties of glass powder cementitious sand, this study uses glass powder of 100-200 mesh and 200-500 mesh to create cementitious sand samples, replacing 10% and 15% of standard sand with equal volume. After curing for 28 days in a standard curing room, the samples are submerged in tap water and a 5% concentration of sodium sulfate solution for 30, 60, 90, 120, and 150 days. Subsequently, the mass loss rate, flexural strength, and compressive strength are measured to reflect the sulfate erosion resistance of the cementitious sand samples containing glass powder. The findings indicate that the flexural and compressive strengths of cementitious sand with waste glass powder experience a swift decline in strength during the pre-erosion stage and a slow decline or even an increase in strength during the post-erosion stage as erosion age progresses. As the glass powder dosage increases, there is a noticeable decrease in the flexural and compressive strengths, in which the doping of 200-500 mesh doped with 15% of glass powder has the worst effect on the resistance to sulfate erosion. As the particle size increases, both flexural and compressive strengths significantly improve, suggesting that sulfate erosion properties are gradually enhanced. The primary reason for this phenomenon is that when glass powder substitutes fine aggregate, the activity develops more slowly in the initial stage, primarily filling the pores and cracks. However, the activity increases rapidly later, more fully integrating with the cement mortar in sodium hydroxide's hydration product to create dense hydrated calcium silicate crystals. This enhances the overall strength of the sample, filling the pore structure within the system, and is more conducive to resisting the erosion effect of sulfate ions on the sample.