集料与硅酸盐水泥石界面区的若干研究

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。

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

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.