硅灰对粉煤灰-磷尾矿基地聚物注浆材料泛碱的影响研究

Study on Influence of Silica Fume on Alkali-induced Efforescence of Fly Ash-Phosphorus Tailings-based Geopolymer Grouting Material

多项研究表明硅灰可用作抑制碱激发地质聚合物泛碱行为的添加剂,但硅灰易与体系中的碱分发生反应,且在不同水固比、粉砂比等条件下其对泛碱行为的影响及其机理目前并不明确。该研究以粉煤灰-磷尾矿砂为基体原材料,NaOH为碱性激发剂,通过浸出实验和微观分析,并对泛碱行为进行了量化表征,考察了不同硅灰添加量、水固比和粉砂比条件下硅灰对粉煤灰-磷尾矿砂基地质聚合物泛碱的影响。结果表明,较于单一NaOH激发组,硅灰的添加可以大幅度降低碱激发地质聚合物Na+浸出量及其浸出液pH值,同时可不同程度地增加样品体系致密性;在不同水固比和不同粉砂比条件下,其Na^(+)浸出量的降低幅度各为38.2%~40.8%和21.9%~34.1%,浸出液pH值的降低幅度各为4.7%~6.1%和6.2%~7.9%,说明硅灰的添加明显降低了地聚物泛碱趋势。该研究结果对硅灰在抑制碱激发地质聚合物泛碱行为的应用方面具有一定的参考意义。

A number of studies have shown that silica fume can be used as an additive to inhibit alkaliinduced effusion of geopolymers,but silica fume easily reacts with the alkali in the system,and it can react to effusion under different water-solid ratios and silt ratios.The influence of alkaline behavior and its mechanism are currently unclear.This research uses fly ash-phosphorus tailings sand as the base material and NaOH as the alkaline stimulant.Through leaching experiments and microanalysis,the efflorescence behavior is quantitatively characterized,the influence of silica fume on the efflorescence of fly ashphosphorus tailing sand-based geopolymer under under conditions of different silica fume additions,watersolid ratios and silt ratios.Results show that,compared with the single NaOH excitation group,the addition of silica fume can greatly reduce the Na+leaching amount of alkali-activated geopolymers and the pH value of the leaching solution,and at the same time can increase the compactness of the sample system to different degrees.Under different water-solid ratios and different silt ratios,the reduction of Na^(+)leaching amount was 38.2%~40.8%and 21.9%~34.1%,respectively,and the pH value of the leaching solution was 4.7%~6.1%and 6.2%~7.9%,respectively,indicating the addition of silica fume significantly reduces the efflorescence tendency of the geopolymers.The research results have certain reference significance for the application of silica fume in inhibiting alkali-induced efflorescence behavior of geopolymers.