Analysis of pentasodium triphosphate hydration kinetics

The present work analyzes the effect of various factors on the hydration of pentasodium triphosphate. The experimental method is based on application of the hydration test. Technical-quality products with different proportions of phase I and phase II have been used. The variables studied are phase I/phase II ratio, initial temperature, particle size, stirring rate and composition of the slurry (presence of hexahydrate crystals and water hardness). The results have been discussed according to a kinetics model that includes a series of stages of a physical nature (dissolution of anhydrous salt and the crystallization of the hexahydrate), as well as of a chemical nature (solvation of the ions in solution). Crystallization of the hexahydrate may be the controlling stage in the process.     

涵闸工程施工期混凝土温度监测系统与水化热参数反演

针对涵闸工程混凝土温控防裂需要,研制了全自动化数字测温系统。该系统的硬件部分由数字式温度传感器、采集单元、GPRS DTU组成,软件部分包括中心服务器软件和客户端软件。系统实现了GPRS公用无线网络覆盖范围内无人值守、多测点远程测量和数据实时共享,具有体积小、无需布线、运行稳定、精度高等特点。经过实际工程多次应用,系统运行稳定可靠,达到预期性能。基于以上系统的测量数据,结合三维非稳定温度场数值计算,对特定工程的水化热参数进行了反演。规范给出普硅42.5水泥水化热参数为m=0.69,n=0.56;而根据实测数据反演的结果为m=1.85,n=0.79。根据两组参数分别进行了三维温度应力计算,得到完全不同的计算结果,前者温度应力未超标,后者多处超标需要采用温控防裂措施才能保证结构防裂安全。因此对实际工程进行温度监测和水化热参数反演是非常必要的。     

HEC influence on cement hydration measured by conductometry

Cellulose ethers are of universal use in factory-made mortars, though their influences on mortar properties at a molecular scale are poorly understood. Recent studies dealt with the influence of hydroxyethylmethyl cellulose (HEMC) and hydroxypropylmethyl cellulose (HPMC) molecular parameters on cement hydration. It was concluded that the degree of substitution is the most relevant factor on cement hydration kinetics, contrary to the molecular weight. Nevertheless, the major role played by the substitution degree has not been verified for other types of cellulose ethers such as hydroxyethyl cellulose (HEC), which generally possesses a higher hydration retarding capacity compared to HPMC and HEMC. In this frame, a study of the impact of HEC molecular parameters on cement hydration was performed. A negligible influence of the molecular weight was observed. Moreover, the results emphasize that the hydroxyethyl group content mainly determines the delay of cement hydration.     

机械激活矿渣水泥

用于式高能振动磨机械激活矿渣（炉渣和／或硅灰）水泥。研究表明：经机械激活后．矿渣水泥的颗粒粒度降低，颗粒的比表面积增大。在掺合了矿渣的水泥中硅微粒聚团经机械激活后可有效地分散并作用于水泥中．使矿渣水泥的水化反应括性增强，促进水泥水化反应，降低水泥制品的孔隙度．从而可以提高水泥制品的力学性能。通过Fourier变换红外光谱和核磁共振等方法分析了机械激活作用的机理。     

Hydration Study of the System Ca3Al2O6–CaSO4· 2H2O–Ca(OH)2–H2O with and without Citric Acid

Hydration occurring in the system Ca₃Al₂O₆–CaSO₄· 2H₂O–Ca(OH)₂–H₂O has been studied at different temperatures and it was found that the reactions are diffusion controlled. The kinetic data obeyed Jander's equation and the rate of reaction increased with increasing temperature. X-ray diffraction studies and calorimetric measurements show that when gypsum is consumed, ettringite is converted into monosulfate. The rate of this conversion also increased with the increasing temperature and decreased in the presence of citric acid. Spectroscopic studies showed that there was some interaction between citric acid and the cement and that the product of hydration is of colloidal nature. Zeta potential measurements show that retardation of Ca₃Al₂O₆ hydration in the presence of gypsum and Ca(OH)₂ is not due to SO²⁻₄ adsorption. Electrical conductivity and thermoelectric potential measurements of solid Ca₃Al₂O₆ show that Ca₃Al₂O₆ is an n -type semiconductor and contains defects. The retardation of Ca₃Al₂O₆ may be due to poisoning of reaction sites by gypsum and Ca(OH)_2.     

我国明矾石的物化性质及其在水泥中的水化硬化

本文系统地介绍了我国明矾石的地质成因、化学成份和矿物组成及其在水泥中的水化硬化,提出了明矾石在碱-硫酸盐激发下形成钙矾石的水化机理,综述了我国利用明矾石作为特种水泥、外加剂的原料及作为普通水泥的混合材所取得的应用成果。     

丁苯橡胶对水泥水化过程及水泥石微观结构的影响

用多种实验手段研究了在普通硅酸盐水泥中掺入丁苯橡胶乳液对水泥水化过程的影响，并用扫描电镜分析了掺入丁苯橡胶后水泥石微观结构形态的改变，从而探讨了丁苯橡胶改善水泥石物理力学性能的机理。     

脱硫石膏粉煤灰胶结材水化硬化机理及耐水性研究

以火电厂的两种废渣即脱硫石膏和粉煤灰为主要原料制得的胶结材，其强度明显高于普通石膏制品，软化系数大于０．８５。采用水化热测定、ＸＲＤ和ｐＨ值测定及ＳＥＭ／ＥＤＸＡ分析，并结合宏观试验结果，分析了这种胶结材的水化硬化机理和微结构特点，并对其耐水性提高的原因进行了讨论。     

不同煅烧温度下形成的含氟硫A矿对水泥水化性能的影响

为研究不同煅烧温度下，含氟硫熟料中不同性能、形貌特征的A矿与水泥水化形成钙矾石的关系以及A矿对水泥水化性能的影响，采用工业原料并尽量模拟立窑内煅烧状况，对经1350℃和1425℃温度下煅烧的熟料进行了A矿形貌、A矿水化率及A矿与钙矾石形成关系等系列试验。试验结果表明，在传统的煅烧温度下（1400～l425℃）烧成的熟料．其A矿的固溶程度及A矿含量均比低温（1350℃）烧成的高；掺氟硫复合矿化剂烧制的熟料的A矿具有较高的水化速度，熟料强度较高．其制成的水泥在水化时，液相成分受高固溶程度A矿的水化所控制，所形成的钙矾石较低温煅烧的稳定．且A矿水化产物的形成与钙矾石（AFt）的形成较协调，水泥石机械强度更高。     

大体积混凝土温升与强度增长的试验研究

针对大体积混凝土结构构件实体强度与普通标准养护试块强度发展规律间的差别等问题,通过研究实际工程尺寸试件温度场的分布和实验室混凝土变温养护试验,以不同养护制度下的试块强度得出了大体积混凝土结构实体强度的发展规律,为工程施工提供了依据,成功地解决了工期与质量的矛盾,取得了较好的技术经济效果.