凝灰岩石粉制备胶凝材料及激发剂模数对抗压强度的影响

Preparation of a tuff polymer and the mechanism of alkaline solution influences on compressive strengths

为促进凝灰岩固体废弃物的有效利用,提出一种凝灰岩石粉胶凝材料的制备方法,并通过抗压强度测试、pH值测定、扫描电镜、X射线能谱仪、X射线衍射分析和傅里叶变换红外光谱等表征,探讨了激发剂模数(n(SiO_(2))/n(Na_(2)O))对抗压强度的影响规律及相关机理.结果表明,激发剂模数为0.042~0.055时,试样的28 d最大抗压强度达到71.33 MPa.随着激发剂模数的降低,颗粒表面的溶解程度提高;生成的硅铝酸盐增加,使抗压强度提高,但当模数低于最优值后,孔隙直径增大,石粉颗粒表面的黏结面积减小,造成强度降低.当激发剂模数为0.080~0.150和0.034~0.055时,抗压强度发展分别主要在3~7 d之间和7~14 d之间,与试样浸出液的pH值变化有较好的对应关系.因为碱激发反应过程大量消耗OH−,强度上升;而过高的OH−浓度可能使产物重新解聚,以及片层颗粒间一端静电斥力的增大使颗粒趋向点−面接触,引起强度的下降.

To promote the effective utilization of the tuff powder waste,this paper proposes a preparation method for a tuff polymer.The raw material is the by-product in the machine-made tuff-based aggregate production process.NaOH and Na2SiO3 were added to the raw material successively and cured in an airtight condition at 60℃.Compared to the production of Portland cement,higher temperature excitation was not necessary,and lower carbon dioxide emissions during the chemical reaction were achieved.Based on the compressive strength,pH value,scanning electron microscopy,X-ray energy dispersive spectrometer,X-ray diffraction spectrogram,and Fourier transform infrared spectroscopy tests on samples with a variety modulus(n(SiO_(2))/n(Na_(2)O))of the activator,the mechanism of the modulus of activator influences on the compressive strengths of this tuff polymer was investigated.This work highlights the following:(1)A superior mechanical performance was observed.Results revealed that the optimum modulus was 0.042-0.055 at a range of 0.034-0.150,and the corresponding maximum strength of the tuff powder was 71.33 MPa.(2)The comprehensive microscopic characterization proved the mechanism of strength development.Microscopic characterization results revealed that the alkali activator mainly acted with the surface of tuff powder particles.With the decrease of the modulus of the activator,the dissolution extent of particles increased,and more aluminosilicate was produced,resulting in strength development.When the modulus was below the optimum value,defects such as pore diameter increased,and the contacting area of the polymer on the surface of the tuff particles decreased,resulting in strength deterioration.When the modulus of the activator was 0.150 and 0.080,the strength development occurred between three and seven days.When the modulus of the activator was 0.050,0.042,and 0.034,the strength development mainly occurred between 7 and 14 days.The pH value variety of the leaching solution generally corresponded to strength development.The increased strengths are attributed to the consumption of OH−in the polymerization and polycondensation stages.Meanwhile,a pH value that is too high may result in depolymerization of the production in the polymerization and polycondensation stages.In addition,the electrostatic repulsion increased,and therefore the strengths of the tuff polymer decreased.