Chloride ingress and steel corrosion in cement mortars incorporating low-quality fly ashes

In this study, the microstructure and hydration characteristics of ecocement and normal Portland cement mortars blended with low-quality fly ashes were investigated. In addition, the corrosive behaviours of steel bars embedded in the mortars were studied. Several tests including scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis and differential scanning calorimetry (DSC) were used for the characterization of the mortars. Electrochemical measurement such as linear polarization resistance and AC impedance spectroscopy were also used to monitor the corrosive behaviours of the embedded steel bars in the mortars. The chloride ingress into the mortars was also studied. The results of the various tests are discussed.     

阳离子共聚物CAM－co－DM的合成及絮凝和防膨性能

通过丙烯酰（ＡＭ）的Ｍａｎｎｉｃｈ反应制备的含叔胺基改性丙烯酰胺胺盐酸盐（ＣＡＭ）同二甲基二烯丙基氯化铵（ＤＭ）共聚，得到了共聚物ＣＡＭ－ｃｏ－ＤＭ，其絮凝和防膨性能优于相同阳离子度的共聚物ＡＭ－ｃｏ－ＤＭ。     

Corrosion of an Al-Zn-In alloy in chloride media

In order to explain the electrochemical behaviour of Al-Zn-In based alloys in chloride media, a commercial Al-Zn-In-Si anode and a ternary alloy, Al-5%Zn-0.02%In prepared in our laboratory, were investigated using potentiodynamic techniques, complemented by SEM, EDX and TEM. The influence of alloy composition, agitation and previous cathodisation on the electrochemical response of the alloys was analysed. Results of previous investigations with pure metals (Zn and In) and with binary alloys (Al-In, In-Al, Zn-In) are also considered in this paper for the sake of comparison. The attack initiation on the Al-Zn-In alloy is related to In-Zn rich zones, segregated at grain boundaries. The presence of In in true electric contact with Al and Zn promotes Cl⁻ adsorption at potentials more positive than −1.1 V. Then, the presence of Zn facilitates a surface enrichment of indium by a displacement reaction. This in turn, assures an accumulation of adsorbed Cl⁻, which maintains an active state of the Al matrix.     

聚硫氯化铝和硫酸铝混凝剂使用效果的对比性研究

本文对新型净水剂——聚硫氯化铝和传统的硫酸铝混凝剂的净水效果进行对比研究。聚硫氯化铝在冬季低水温,高氨氮的原水情况下,不仅提高了出厂水水质,而且节省制水成本.并且简化了生产工艺的操作控制,值得推广。     

石油钻井污水就地三级处理技术

本文报道了在井场钻井污水池水面上直接依次喷洒氯化钙溶液、石灰水及铝盐溶液（聚合氯化铝、硫酸铝等）的就地三级处理技术，介绍了这一处理技术的原理、工艺程序及在百色、陆良地区２０余口井现场处理钻井污水的效果。药品用量按该井次待处理污水量由室内实验和现场小型实验所得结果确定。这一处理方法所需设备简单，操作简便，费工少，处理时间短，药品费用低，处理效果好，处理后的污水基本符合国家标准规定的二级综合排放标准，产生的废渣易处理。     

Generalization of the possibility of eliminating the filtration step in the determination of acid-soluble chloride content in cement and concrete by potentiometric titration

In this work, it is demonstrated that it is possible to eliminate the filtration step in the determination of the acid-soluble chloride content of cement and concrete by potentiometric titration, irrespective of the method used for detecting the end-point of the titration. Extensive analytical results are presented corresponding to several types of cement and to a broad range of chloride concentrations in concrete. Some requirements to avoid errors in such analytical determinations are discussed.     

Effect of mixing proportions of concrete on its electrical conductivity and the rapid chloride permeability test (ASTM C1202 or ASSHTO T277) results

The rapid chloride permeability test (RCPT)—American Society of Testing and Materials (ASTM) test method C1202 or American Association of States Highway and Transportation Officials (AASHTO) test method T277—is virtually a measurement of electrical conductivity of concrete, which depends on both the pore structure characteristics and pore solution chemistry of concrete. This paper discusses the effects of several factors, such as cement composition, replacement of cement with supplementary cementing materials and inclusion of aggregate, on the electrical conductivity or RCPT results of hardened cement mortars and concrete. Analyses based on published results have indicated that all the three factors may have significant effects on the chemistry and specific conductivity of concrete pore solution, which has little to do with the transport of ions in the solution. Thus, RCPT is not a valid test for evaluation of permeability of concretes made with different materials or different proportions.     

Investigation in Mathematical Models of Chloride Diffusion Coefficient in Concrete Exposed to Marine Environment

Degradation of RC （reinforced concrete） in maritime structures has become a worldwide problem due to its excessive costs of maintenance, repair and replacement in addition to its environmental impacts and safety issues. Degradation of both concrete and steel which is the main reason of reduction in the service life of RC structures strongly depends on the diffusion process of moisture and aggressive species. In this paper, the major and popular mathematical models of diffusion process in concrete are surveyed and investigated. Predominantly in these models, the coefficient of chloride diffusion into the concrete is assumed to be constant. Whereas, experimental records indicate that diffusion coefficient is a function of time. Subsequently, data analysis and comparisons between the existing analytical models for predicting the diffusion coefficient with the existing experimental database are carried out in this study. Clearly, these comparisons reveal that there are gaps between the existing mathematical models and previously recorded experimental results. Perhaps, these gaps may be interpreted as influence of the other affecting parameters on the diffusion coefficient such as temperature, aggregate size and relative humidity in addition to the water cement ratio. Accordingly, the existing mathematical models are not adequate enough to predict the diffusion coefficient precisely and further studies need to be performed.     

流动注射在线测定环境水样中的氰化物

利用流动注射在线测定环境水样中的氰化物（CN）。实验结果表明,该方法能够满足日常水质分析的要求,做到快速准确。测定范围为2.0-100μg/L,检测限为0.783μg/L,分析速率为18个样/h,加标回收率为：96.7%-102.6%.