污泥渣-低钙粉煤灰地聚合物泛碱抑制研究

Study on Efflorescence Inhibition of Low Calcium Fly Ash Based Geopolymer with Sludge

以低钙粉煤灰为主要原料,添加印染污泥渣,通过碱激发在室温下制备印染污泥渣-低钙粉煤灰地质聚合物(DS-LFAG),利用萘系减水剂、消泡剂及防水剂对DS-LFAG进行泛碱抑制。研究污泥渣及养护龄期对DS-LFAG强度的影响,以及不同外加剂对DS-LFAG性能和泛碱抑制的影响。利用扫描电子显微镜(SEM)和X射线衍射(XRD)仪对DS-LFAG进行性能表征。结果表明,掺入30%污泥渣时,DS-LFAG力学性能最佳,28 d和120 d抗压强度分别达到30.59 MPa和35.63 MPa;加入0.2%萘系减水剂可明显改善DS-LFAG孔径分布,减小孔隙结构,较好地抑制DS-LFAG泛碱,同时提高其强度;加入0.05%消泡剂及0.2%防水剂均可降低DS-LFAG中碳酸根离子含量,具有一定的泛碱抑制效果,但均会导致DS-LFAG强度降低;DS-LFAG强度增长和泛碱现象得到一定抑制,主要是因为其在外加剂作用下产生更加密实的微观孔隙结构并生成新的硅铝酸盐矿物。

The low calcium fly ash based geopolymer with dyeing sludge(DS-LFAG)was prepared by alkali activation at room temperature,and the inhibition effect and micro mechanism of different additives on geopolymer efflorescence were studied.The results show that the mechanical properties of the DS-LFAG are the best when 30%dyeing sludge is added,and the compressive strength of 28 d and 120 d reach 30.59 MPa and 35.63 MPa,respectively.With the addition of 0.2%naphthalene water reducer,the pore size distribution and pore structure of DS-LFAG can be improved obviously,and the strength of DS-LFAG can be improved while the efflorescence is well restrained;the addition of 0.05%defoamer and 0.2%waterproof agent can reduce the content of carbonate ion in DS-LFAG,respectively,hence improve the efflorescence inhibition of DS-LFAG to some extent,but the strength of DS-LFAG also decreases somewhat.The results of scanning electron microscopy(SEM)and X-ray diffraction(XRD)further reveal that the strength growth and the efflorescence inhibition of DS-LFAG are closely related to the formation of more dense microstructure and the generation of new aluminosilicate phase under the action of additives.