不同粘土矿物与聚羧酸减水剂相互作用机理研究

通过X射线衍射(XRD)、红外光谱(IR)、有机碳吸附(TOC)、饱和吸水率以及净浆流动性等试验方法,研究了不同粘土矿物与聚羧酸减水剂的相互作用机理.结果表明:聚羧酸减水剂的侧链可进入粘土矿物蒙脱石的层间,发生插层反应,即层间吸附,而其侧链结构不进入伊利石、高岭土、海泡石等粘土矿物的层间,仅发生表面吸附,且吸附量大小为蒙脱石>高岭土>海泡石>伊利石;饱和吸水率试验显示,粘土矿物的饱和吸水率大小为蒙脱石>高岭土>海泡石>伊利石;流动度试验表明,粘土矿物对水泥-减水剂体系净浆流动度均有不同程度的影响,且蒙脱石影响程度最大.由此可知,粘土矿物对自由水和聚羧酸减水剂的吸附是造成流动度损失的主要原因.

Mechanism of Interaction between Different Clay Minerals and Polycarboxylate Superplasticizer

The interaction mechanisms between different clay minerals and polycarboxylate superplasticizer (PC) were discussed with XRD, IR and TOC, saturated water absorption and fluidity.The results show that the side chains of PC can be intercalated into the interlayer of montmorillonite (MMT), thereby causing the interlayer absorption, whereas PC is not able to be inserted into the interlayer of kaolinite, sepiolite and illite;and the only surface adsorption can be observed and the order of adsorption amount montmorillonite > kaolinite > sepiolite > illite.The results of saturated water absorption indicate that the orders of different clay minerals are montmorillonite > kaolinite > sepiolite > illite.The presence of clay minerals would reduce the fluidity of cement-PC paste, and the effect of montmorillonite is the greatest.Therefore, the main reason for the fluidity loss is attributed to absorption of free water and adsorption of polycarboxylate superplasticizer caused by clay minerals.