粉煤灰对碳硫硅钙石型硫酸盐侵蚀的影响

Effects of Fly Ash on Thaumasite Form of Sulfate Attack

摘要:

用粉煤灰等质量替代20%，30%，50%水泥后，将水泥石灰石粉粉煤灰净浆样品置于（5±2）℃的10%（质量分数）硫酸镁溶液中15个月，加速碳硫硅钙石型硫酸盐侵蚀（TSA）.对腐蚀产物进行了红外光谱定性分析和X射线衍射定量分析，通过灰色关联分析研究了粉煤灰对TSA的影响.结果表明：粉煤灰对水泥基材料的TSA影响与其组成、掺量及细度等因素有关；粉煤灰活性指数对碳硫硅钙石形成影响最大，可作为筛选粉煤灰预防TSA破坏的指标；活性指数大于80%的粉煤灰，其掺量达到50%时可显著改善水泥基材料的抗TSA性能.

Abstract:

Cement was equally replaced by fly ash with 20%, 30% and 50% proportions. Cement limestone fly ash paste samples were immerged in 10% magnesium sulfate solution(by mass) at (5±2)℃ for 15months to accelerate thaumasite form of sulfate attack(TSA). The corrosion products were qualitatively analyzed by infrared spectrum(IR) and quantitatively analyzed by X ray diffraction(XRD)/Rietveld refinement methods. The effect index of fly ash on TSA was investigated by gray correlation analysis. The results show that:effects of fly ash on TSA are closely related to the composition, content of fly ash. The activity index of fly ash has a maximum gray correlation degree to quantity of thuamasite formation which could be used as an index for filtering fly ash to prevent TSA. Fly ash with an activity index >80% could improve the resistance to TSA in cement based materials when the content reached 50%.