NO_(2)-LDH对减水剂作用效果的影响及机理

Influence and Mechanism of NO_(2)‑LDH on Effect of Superplasticizer

采用焙烧还原法制备了亚硝酸根插层水滑石(NO_(2)-LDH),并研究了其对减水剂吸附分散及增强效果的影响.结果表明:NO_(2)-LDH的层间距和结晶度较原碳酸根型镁铝水滑石均略有降低;NO_(2)-LDH与减水剂之间存在阴离子交换,降低了减水剂的吸附分散效果,且减水剂分散效果的降低程度随着NO_(2)-LDH掺量的增加而增大;NO_(2)-LDH对掺减水剂砂浆抗折强度的影响不明显,对抗压强度略有提升;NO_(2)-LDH对萘系高效减水剂分散效果的影响大于对聚羧酸系减水剂的影响.

Nitrite intercalation hydrotalcite(NO_(2)-LDH)was prepared by roasting and reduction method,and its effect on adsorption,dispersion and enhancement of superplasticizer were studied.The results show that the layer spacing and crystallinity of the NO_(2)-LDH are slightly lower than that of protocarbonate type Mg-Al hydrotalcite.There is anion exchange between NO_(2)-LDH and superplasticizer,which reduces the adsorption and dispersion effect of superplasticizer.The decreasing degree of dispersion effect of superplasticizer increases with the increase of NO_(2)-LDH content.NO_(2)-LDH has no obvious effect on the flexural strength of mortar mixed with superplasticizer,but the compressive strength is slightly increased.The effect of NO_(2)-LDH on the dispersion of naphthalene superplasticizer is greater than that of polycarboxylic acid superplasticizer.