碾压混凝土中高掺石灰石粉与粉煤灰的耦合作用

以占胶凝材料总量60%的石灰石粉与粉煤灰进行不同比例复掺,开展了不同胶凝材料碾压混凝土的抗压强度、抗冻性能和抗渗性能试验研究,利用水化热、扫描电镜以及压汞法对不同比例石灰石粉与粉煤灰胶凝体系的水化过程与微结构形成进行了分析。研究发现,当石灰石粉与粉煤灰总量占胶凝材料总量的60%且石灰石粉取代粉煤灰比例为50%时,由于早期石灰石粉促进水化加上粉煤灰的填充效应、后期粉煤灰的火山灰活性以及石灰石粉的密实效应,二者的耦合作用可使得碾压混凝土形成密实的微结构,获得良好的力学性能和耐久性能。     

Synthesis Mechanism and Material Characterization of C<Subscript>4</Subscript>AF Obtained by the Self-propagating Combustion Reaction Method

To investigate the influence of preparation process on the properties of synthesized C₄AF, the powder was prepared via the self-propagating combustion reaction (SPCR) method using urea as fuel and metal nitrates as cation precursors. Synthesis mechanism of the SPCR method, calculation and adjusting principles of urea dosage were detailedly introduced. Material characterization of synthesized C₄AF was performed with the aid of X-ray diffractometry, Fourier transform infrared spectrometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, ²⁷Al nuclear magnetic resonance and isothermal microcalorimetric technique. Remaining content of transition phase of calcium carbonate in synthesized C₄AF was determined by quantitative analysis of X-ray diffractometry. It was found that there was no difference in the hydration behavior of C₄AF synthesized by the SPCR method and the traditional solid-state reaction (SSR) method. C3AH6 and amorphous iron (III) hydroxide (Fe(OH)₃) would be formed during the hydration of C4AF while CH not. Crystallite size of synthesized C₄AF was 16.1 Å and the apparent activation energy was 36.2 kJ/mol. Coordinated condition of Al in C₄AF can be detected by ²⁷Al NMR technique, but the peaks were broadened and the intensities were relatively low, supporting the use of ²⁷Al NMR for the quantitative analysis of C₃A in Portland cements.     

Synthesis Mechanism and Material Characterization of C_4AF Obtained by the Self-propagating Combustion Reaction Method

To investigate the influence of preparation process on the properties of synthesized C_4AF,the powder was prepared via the self-propagating combustion reaction(SPCR)method using urea as fuel and metal nitrates as cation precursors.Synthesis mechanism of the SPCR method,calculation and adjusting principles of urea dosage were detailedly introduced.Material characterization of synthesized C_4AF was performed with the aid of X-ray diffractometry,Fourier transform infrared spectrometry,scanning electron microscopy,energydispersive X-ray spectroscopy,~(27)Al nuclear magnetic resonance and isothermal microcalorimetric technique.Remaining content of transition phase of calcium carbonate in synthesized C_4AF was determined by quantitative analysis of X-ray diffractometry.It was found that there was no difference in the hydration behavior of C_4AF synthesized by the SPCR method and the traditional solid-state reaction(SSR)method.C_3AH_6 and amorphous iron(III)hydroxide(Fe(OH)_3)would be formed during the hydration of C_4AF while CH not.Crystallite size of synthesized C_4AF was 16.1?and the apparent activation energy was 36.2 kJ/mol.Coordinated condition of Al in C_4AF can be detected by ~(27)Al NMR technique,but the peaks were broadened and the intensities were relatively low,supporting the use of ~(27)Al NMR for the quantitative analysis of C_3A in Portland cements.     

相变温控大体积混凝土的设计

早期热裂缝已成为影响混凝土结构耐久性的制约因素之一，期望研制一种水化热自控的智能混凝土，以期避免和预防早期热裂缝，进而改善混凝土的耐久性。近年来，具有相变潜热大、相变过程等温或近似等温的相转变材料用于建筑物太阳能贮存方面的研究成为热点。已有研究表明，存在适宜于混凝土碱性环境的PCM。本在分析早期热裂缝的产生机理以及PCM用作热能贮存和温度控制的基础上，提出以PCM作为水化热自控的温敏元素，并详细讨论了其可行性以及PCM的选择、用量的确定与置入工艺等，介绍了该种新型混凝土的特点与预期的温控防裂效果．其研究和开发将推动智能混凝土的进一步发展。     

高气温时缓凝剂对RCC层面允许暴露时间的影响

通过对碾压混凝土层面抗剪（断）参数的测定，计算了碾压混凝土层面允许暴露时间，并分析了高气温缓凝剂对碾压混凝土层面允许暴露时间的作用。     

土体固结剂（HEC）固化三工程弃渣试验

粉末状高强高耐水土体固结剂，不仅可用来固化各种土体，使之具有强度，耐水性和耐久性，而且还可以作为混凝土的胶凝材料，其特点是掺量少，固结范围广，固结强度高、水稳定性好、使用简便、就地取材、降低造价，缩短施工周期等。     

高性能耐磨蚀混凝土修补材料性能的试验研究

针对工程实际中耐磨蚀混凝土修补材料存在的问题,试验研究了复掺LY-1、LY-2和S.F配制的高性能混凝土的力学性能、变形性能和耐冲磨性能。成果说明,通过适当比例复掺LY-1、LY-2和S.F,增强了胶结材料的活化作用,提高了密实度,改善了界面过渡区结构,增加了新老混凝土界面粘结力,获得了较满意的修补性能,为研究和开发优质耐磨蚀混凝土修补材料提出了一条可行途径。     

圆度目标函数单谷性的研究

提出了一种研究圆度目标函数单谷性的方法，用实例证明了圆度目标函数为单谷函数，为用最优化原理迅速而准确地求解圆度目标函数的极值提供了理论依据。     

无宏观缺陷水泥基复合材料的水敏特性及其破坏机理研究

无宏观缺陷（ＭＤＦ）水泥基复合材料的水敏性问题是这种高抗折强度瓣致命弱点。本工作研究了高铝水泥／聚乙烯醇基ＭＤＦ复合材料吸温后对其物理力学性能和生观结构的影响。结果表明,ＭＤＦ复合材料在１００％相对湿度中的吸湿过程初始受扩散动力学控制,吸湿量取决于聚合物的含量,水透过复合材料的扩散系数为１０＾０８ｃｍ＾２／ｓ数量级;其在水中的强度随浸水时间的延长连续下降,同时伴有不可忽视的一膨胀。ＭＤＦ复合材料的