矿物掺合料对地聚合物抗冻性能的影响

以碱激发偏高岭土制备地聚合物混凝土,分别研究了掺入15%的钢渣、矿渣或粉煤灰的地聚合物混凝土的力学抗压强度和抗冻性能,测试了地聚合物混凝土的真空饱水体积吸液率,运用XRD、SEM和DSC-TG等测试方法分析了矿物掺合料对地聚合物微观结构和水化产物的影响。结果表明:钢渣或矿渣能有效提高地聚合物混凝土的抗压强度,而粉煤灰的掺入使其强度稍有降低;地聚合物表观形貌中存在较多的孔洞和微裂缝导致其抗冻性能较差,掺入钢渣或者矿渣后地聚合物形成了新的产物C-S-H凝胶、C-A-S-H凝胶等并填充在结构中形成更加密实的板状结构,降低了地聚合物混凝土冻融破坏速率,五次冻融循环后地聚合物的相对强度均在90%以上,抗冻性能得到提高;粉煤灰降低了制备地聚合物混凝土的用水量且未水化的粉煤灰颗粒镶嵌在结构中增加了其密实性和抗冻性能,五次冻融循环后相对强度为86.9%,基准组的相对强度仅为79.7%。

Effect of Mineral Admixtures Incorporation on Frost Resistance of Geopolymer

Geopolymer concrete was prepared with metakaolin and alkali-activator.The compressive strength and frost resis-tance of geopolymer concrete with a dosage of steel slag,slag or fly ash of 15％ was studied and the vacuum volume aspiration ratio of geopolymer concrete was tested.XRD,SEM and DSC-TG analyses were used to investigate the effect of mineral admixtures incor-poration on the microstructures and hydration products of geopolymer.The results showed that the compressive strength of geopoly-mer concrete is effectively improved by steel slag or slag,but the fly ash could make it slightly decrease.The poor resistance of frost can be attributed to the pores and microcracks exist on the surface of geopolymer.The adding of steel slag or slag forms the hydration products such as C-S-H ,C-A-S-H gel which fill in the pores can delay its rate of destruction induced by the cycle of freezing and tha-wing and improve the frost resistance of geopolymer,it maintains relative strength in 90％ after 5 freeze-thaw cycles.The fly ash re-duces the water consumption to prepare concrete and the unhydrated fly ash particles embedded in the structure contributes to the im-provement of density and frost resistance,as the geopolymer concrete maintained 86.9％ strength after 5 freeze-thaw cycle,and 79.7％ for the control group.