集料与硅酸盐水泥石界面区的若干研究

Investigations on the Inter facial Zone between Aggregate and Paste of Portland Cement

利用XRD层析法和SEM研究了集料与硅酸盐水泥石界面区的组成、CH晶体取向指数等。实验结果表明,界面区中水化产物主要是C-S-H凝胶、CH晶体、AFt、孔隙以及未水化的熟料矿物;界面区中CH晶体发育良好,取向作用较强,界面处它以(001)面平行于集料表面生长;水化龄期增长或水灰比提高时,CH晶体取向作用增强,而且水灰比高时,界面区中孔洞、裂纹增多,降低界面粘结强度;水泥中掺入5.0%wt硅灰后,CH晶体取向作用下降;水泥中掺入5.0wt%FDN减水剂,由于水泥早期水化程度低,对水泥石-集料早期粘结强度不利,但28d后其粘结强度就能赶上并超过其它试样。

The composition and structure of the interfacial zone between aggregate (white marble,limestone, granite) and paste of portland cement as well as the orientation coefficient of portlandite(I_(CH)) were preliminarily studied by XRD and SEM method. The main products of the zone are C-S-H gel, portlandite, AFt and pores, cracks as well as unhydrated portland clinker particles. Port-landite not only grows well but also exists in orientating forms, and near the interface it exists in astate parallel to the surface of aggregate by its (001) lattice plane. I_(CH) rises with the increase of ce-ment water ratio(W/C) and the development of the cement hydration. Higher the W/C, more thepores and cracks in the zone. W/C bears an exact relation to the decrease of bond strength. I_(CH). is de-creased when 5.0wt% silica fume is added to cement. Bond strength at early age is reduced by 0.5% added FDN (one kind of water-reducing admixture)due to the retarded hydration of cement,but it increases continually and becomes greater than that of other samples after 28 days.