纳米SiO_(2)改性聚合物水泥基材料性能试验研究

Experimental Study on Property of Polymer Cement Based Composite Modified by Nano-SiO_(2)

利用纳米SiO_(2)(Nano-SiO_(2),NS)可以促进聚合物水泥基材料水化,提升其力学性能、改变其水化产物微观形貌及界面过渡区(Interface Transition Zone,ITZ)性能等特点,采用电液式压力试验机、水泥胶砂干缩比长仪、X射线衍射技术(X-ray Diffraction,XRD)、扫描电镜(Scanning Electron Microscope,SEM)、X射线能谱仪(Energy Dispersive Spectrometer,EDS)及显微硬度试验等各种宏观与微观测试手段相结合的方法对NS改性聚合物水泥基材料的力学性能、干缩性能、水化产物微观形貌与组成及ITZ相关性能进行研究.结果表明:掺加NS后,大大提高了聚合物水泥砂浆的力学性能,尤其对早期强度提高更为明显.随着NS的掺入,聚合物水泥砂浆干缩率增大,在早期干缩现象更加明显;NS加入改变了聚合物水泥基材料水化产物的数量及C-S-H凝胶微观形貌及组成,促进了聚合物水泥基材料的水化并且降低了C-S-H凝胶的钙硅比.对于ITZ性能,NS掺入使得聚合物水泥硬化浆体-骨料ITZ形貌变得更加致密,减少了ITZ明显的裂缝和孔洞,并且ITZ水化产物丰富密集,C-S-H凝胶明显增多,显微硬度升高.

The utilization of Nano-SiO_(2)(NS)in polymer cement based composite can promote its hydration rate,enhance its mechanical property,change its microstructure of hydration products and improve its performance of interface transition zone(ITZ).Hence,mechanical properties,drying shrinkage property,microstructure and composition of hydration products and ITZ related performance of polymer cement based composite modified by various dosages of NS were studied by adopting the combination of macro and micro methods,including electro-hydraulic pressure testing machine,cement mortar comparator,X-ray diffraction(XRD),scanning electron microscope(SEM)and X-ray energy spectrometer(EDS).The test results reveal that NS can enhance the strength of the polymer cement mortar(PCM),especially at the early age.With the incorporation of NS,the dry shrinkage rate of PCM increases,which is also more significantly pronounced at the early age.It can be seen from XRD and SEM results that the degree of polymer cement based composite hydration is accelerated because of mixing NS.Pozzolanic reaction of NS can alter the number,microstructure and composition of hydration products of polymer cement based composite,and reduce the Ca/Si atomic fraction ratio of C-S-H gel.ITZ between polymer cement hardened paste and aggregate is improved due to the reaction of NS with Ca(OH)2 rapidly,resulting in a more compact structure without obvious cracks and holes.It tends to be an increased micro-hardness in ITZ as a result of the dense hydration products and the generation of more C-S-H gel.