减水剂对C3A早期水化过程的作用

Effects of Superplasticizers on Early Hydration of C3A

关键词:  减水剂  铝酸三钙  插层水化物  水化硫铝酸钙  吸附

Key words:  superplasticizer  C3A  intercalated hydration product  calcium sulphoaluminate  adsorption

摘要:

通过X射线衍射（XRD），总有机碳法（TOC）和化学分析，研究了聚羧酸减水剂（PCA）、萘系减水剂（PNS）和脂肪族减水剂（SAF）对铝酸三钙（C3A）早期水化过程的影响.研究发现：C3A对减水剂的吸附作用因减水剂品种不同而不同；3种水化体系中均形成了有机金属矿物相（OMP），且掺PNS体系生成的OMP的XRD特征衍射峰强度和宽度均大于掺PCA和SAF体系；PCA和PNS加速了C3A的水化进程，SAF抑制了C3A早期的溶解沉淀过程；PNS对水泥初期水化硫铝酸钙生成量的影响较小，而PCA和SAF促进了水泥水化初期单硫型水化硫铝酸钙的形成.减水剂对C3A早期水化过程的作用揭示了减水剂与水泥适应性的本质.

Abstract:

Influences of polycarboxylate superplasticizer （PCA）, polynaphthalene sulphonate superplasticizer （PNS） and aliphatic superplasticizer （SAF） on early hydration of C3A were investigated by X ray diffraction （XRD）, total organic carbon （TOC） measurement and chemical analysis. Experimental results indicate that the adsorptions of three kinds of superplasticizers on C3A are different. Organo mineral phases （OMP） are formed in all three kinds of hydration systems, and the intensity and width of characteristic diffraction of OMP for PNS system are higher than those for PCA and SAF systems. PCA and PNS accelerate the hydration process of C3A, however, SAF inhibits the dissolution precipitation process of C3A at early age. Effect of PNS on the formation of calcium sulphoaluminate is less than that of PCA and SAF, while PCA and SAF can accelerate the formation of calcium monosulphoaluminate at initial hydration stage. The study of effects of superplasticizers on early hydration of C3A reveals the essence of compatibility between superplasticizers and cement.