High performance metakaolinite based cementitious materials were prepared with metakaolinite as main component, and the different modules of Na and Na-K silicate solutions as diagenetic agent. The results show that the mechanical properties are affected by different silicate solutions, compressive strengths of pastes hydrated for 3 d and 28 d with Na-K silicate solution (The modulus is 1) are about 43.68 and 78.52 MPa respectively. By analyzing the mechanical properties of Metakaolinite based cementitious materials, the diagenetic effect of lower module is better than higher module, and Na-K silicate solution is better than Na silicate solution. The structure of the Na and Na-K silicate solutions is studied with IR and ^(29)Si NMR, the reason of the lower module and Na-K silicate solution improving the mechanical properties is that the low module silicate solution has lower polymeric degree of silicon dioxide, and the higher polymeric degree of silicon oxide tetrahedron(Q^4) in Na-K silicate solution is less han Na silicate solution.
Slag,fly ash,gangue and 500℃ calcined gangue are analyzed by using identical coupled plasma optical emission spectroscopy (ICP),X-ray photoelectron spec-troscopy (XPS),infrared spectroscopy (IR) and magnetic angle spinning nuclear magnetic resonance (MAS NMR). Research results show that there is a negative linear relationship between the Si 2p and Al 2p binding energies of Al-Si materials and the compressive strength of aluminosilicate based cementitious materials prepared with these Al-Si materials,i.e. the lower the binding energies,the higher the compressive strength. Indeed,the Si 2p and Al 2p binding energies of Al-Si materials can be used to indicate their hydraulic activity. The binding energies of the four examined materials increase in the order of slag,fly ash,500℃ calcined gangue and untreated gangue. Moreover,the binding energies of Si 2p,Al 2p and O 1s of every Al-Si material have excellent correlation. By using the Al 2p binding energy and 27Al MAS NMR spectra,the coordination number of aluminum in slag is determined to be four,while that in gangue,is six. Based on the aforementioned discoveries,this paper presents a new effective method to evaluate the hydraulic activity of Al-Si materials by using the surface binding energies of silicon and alu-minum of Al-Si materials.
用X射线光电子能谱(XPS)对热处理煤矸石中Si 2p,A l 2p和O 1s的结合能进行试验研究,发现煤矸石质硅铝基胶凝材料的强度和煤矸石中硅、铝的结合能具有线性关系,煤矸石的硅、铝结合能可以用来表征煤矸石的胶凝特性和活性.热活化煤矸石Si 2p,A l 2p和O 1s的结合能之间具有很好的相关性.基于此提出硅铝质物料活性评价的新方法———用Si,A l表面结合能评价硅铝质物料活性.
To study the dissolution mechanism of gangue, dissolution characteristics of the gangue samples calcined at different temperatures in alkaline solutions and alkali metal silicate solutions with respect to Si and Al ions were analyzed by identical coupled plasma optical emission spectroscopy (ICP). The results show that the extent of dissolution of Al and Si varies with calcination temperature. It shows that the samples have a higher degree of dissolution in NaOH than in KOH medium. Si and Al appear to have synchro-dissolution behavior in alkaline solution, which means that Si and Al could dissolve from the mineral surface in certain linked forms. The result that a higher degree of dissolution exists in sodium silicate solution and a lower degree of dissolution exists in sodium-potassium silicate solution of Al is proved by the 29Si NMR spectra and the mean connectivity degree of these alkali metal silicate solutions.
