单氟磷酸钠对天然碳化高炉矿渣砂浆的影响(英文)

研究了10%的单氟磷酸钠溶液作为表面处理剂对碳化高炉矿渣水泥砂浆耐久性的影响。砂浆养护10d后或暴露在自然环境中1a后,进行表面处理,这2种处理方式分别称为前处理与后处理。通常情况下,砂浆在碳化侵蚀后其微观结构被严重破坏。处理后的砂浆经碳化后的微观结构大为改观。试验结果表明:处理后的碳化高炉矿渣水泥砂浆的抗冻融循环能力得到了很大提高。     

混凝土应力腐蚀研究现状

为了更好表达建筑结构耐久性的真实情况,了解、掌握应力作用’下混凝土的耐久性问题,介绍了混凝土结构在氯离子、硫酸盐、碳化等因素影响下的腐蚀效应,对混凝土应力腐蚀的研究现状进行了评述。     

混凝土结构耐久性的近期研究进展

首先陈述了因耐久性问题所造成的严重经济损失,然后介绍了混凝土结构耐久性的主要内容,综述了当前混凝土结构耐久性的研究现状,最后指出了今后的研究重点及发展趋势。     

水蒸气对石灰石/白云石循环吸收CO_2能力影响

利用自制能实现等温下热重测量的实验系统,研究了水蒸气对不同粒径范围(75~97μm,150~250μm,355~450μm)石灰石与白云石在循环煅烧/碳酸化过程中对CO2吸收能力的影响。结果表明,当不考虑水蒸气时,白云石对CO2的吸收能力要高于石灰石;而考虑水蒸气时,两者对CO2的吸收能力则相差不多。碳酸化阶段水蒸气的存在提高了钙基吸收剂对CO2的吸收能力,尤其对石灰石作用更加明显。如在20%水蒸气下,石灰石循环第8次对CO2的吸收能力为0.24 g/g,而无水蒸气时仅为0.18 g/g。实验结果表明:比较石灰石与白云石对CO2的循环吸收能力时,水蒸气是重要的影响因素。     

Effects of Ethanol,Carbonation and Hop Acids on Volatile Delivery in a Model Beer System

A model beer was created to investigate the effects of ethanol, carbonation and hop acids on volatile release (ethyl acetate, isoamyl alcohol and phenethyl alcohol) using both headspace analysis and in‐nose measurement during consumption. None of the factors were found to impact on equilibrium headspace partitioning, however headspace sampling after short term decanting revealed minor and compound specific effects of each of the components. When measured in‐vivo, hop acids had no significant effect on volatile delivery; however ethanol significantly increased the delivery of volatiles during consumption. This increase was sustained throughout the release profile. Carbonation was found to increase the release of ethyl acetate and isoamyl alcohol during the first release peak after swallowing, but had no significant effect on phenethyl alcohol. Furthermore, ethyl acetate was increased by carbonation in the second peak after swallowing, but this effect was not found to be persistent in subsequent peaks. These results indicate a trend between the compound's air‐water partition coefficient and the effects of carbonation in‐vivo. The effects of ethanol and carbonation seemed to be independent and therefore an additive effect is possible. This study highlights the difference between data collected by headspace and in‐vivo means.     

收缩裂缝对混凝土氯离子渗透及碳化的影响

采用大板开裂方法制备了收缩裂缝宽度为0.07 mm、0.1 mm、0.2 mm、0.4 mm和0.62mm的混凝土试件,对养护7 d的不同尺度裂纹混凝土海水浸泡腐蚀30 d,以及快速碳化14 d.测试混凝土裂缝处及周边区域的碳化深度、自由氯离子及总氯离子浓度.试验结果表明:混凝土的自由氯离子与总氯离子均随裂缝宽度增加而...     

Effect of concrete carbonation process on the passivating products of galvanized steel reinforcements

The composition of passivating products on galvanized steel reinforcement in concrete during carbonation was studied. Cube‐shaped concrete specimens were manufactured with Portland 52.5 R cement and reinforced with hot‐dip galvanized steel sheets obtained from pure Zn and Zn? Sn? Bi? Ni alloy bath. The concrete specimens were exposed to air curing for 28 days and then to the carbonation chamber. Corrosion rate and potential measurements were performed both during the curing in air and exposure in a carbonation chamber. At defined periods of time, some concrete specimens were broken and the galvanized steel sheets were submitted to XRD, SEM observations and EDX analysis. The growth of the passivation products was evaluated by integrating the diffraction peaks. XRD analysis and SEM observations show that the layer of calcium hydroxyzincate (CaHZn), formed on the galvanized sheets during the air curing, is destroyed by the concrete carbonation process. However, potential measurements indicate that the galvanized steel always remains in the passive state. X‐ray diffractometry was not able to identify the new passivating product; EDX maps suggest the presence of zinc carbonates.     

超重力法合成立方形纳米级碳酸钙碳化过程研究

采用pH检测仪和电导率仪,TEM分析及粒度分布测试等对Ca(OH)2H2OCO2系统合成CaCO3的反应过程进行跟踪检测,结果发现:碳化反应前期,为CO2吸收控制,反应后期受Ca(OH)2溶解控制。立方形碳酸钙的形成,经历了由针状体变小,生成线束状中间体,经过葡萄串状形态,再断裂成粒径在15～30nm规整立方形晶体的过程。     

超细碳酸钙的连续鼓泡碳化生产新工艺

介绍了连续鼓泡碳化法生产超细碳酸钙工艺流程及特点。将用该法生产的超细碳酸产品与连续喷雾碳化法的产品进行比较。     

Effects of stabilizers on CO2 fixation capacity in neutralization of alkali construction sludge

Construction sludge, generated from tunneling and piling, is typically in a liquid state. It can be improved via physical treatments, such as dehydration, and/or chemical treatments, using stabilizers, in order to to be recycled as construction material. To adjust the strength of sludge, chemical treatments are often preferred. However, chemical treatments frequently result in alkali leaching. Methods to reduce alkalinity by curing the alkaline sludge under CO₂ gas at a certain concentration have been proposed in Japan. In recent years, technologies that utilize CO₂ to improve the quality of cementitious material have received considerable attention in terms of carbon capture. Therefore, the effects of stabilizers on the CO₂ fixation capacity of alkaline sludge during pH neutralization were investigated in this study. Accelerated carbonation and carbonate content measurement tests were conducted to detect the CO₂ content fixed in alkaline sludge specimens treated with various stabilizers. The test results showed that the fixed maximum CO₂ content per gram of dry mass of sludge, (m_CO2)^max, increased with the calcium oxide (CaO) content of the stabilizer(s) per gram of dry sludge, C_CaO. However, the rate of increase in (m_CO2)^max with C_CaO was significantly affected by the type of stabilizer used. In the case of quicklime (QL), the ratio of (m_CO2)^max to C_CaO was approximately 0.5, whereas, in the cases of fly ash (FA) and steel slag (SS), the ratio was approximately 0.25. The ratios for biomass ash and paper sludge ash were between that for QL and that for FA and SS. Detailed analyses of the test results suggest that the CaO content per gram of stabilizer(s) in the sludge, C*_CaO, can provide an estimate of the fixed maximum amount of CO₂ per gram of stabilizer(s) in the sludge, (m*_CO2)^max. However, other factors, including the amount of water-soluble Ca, should be considered for a precise evaluation. Additionally, the experimental results showed that the decrease in pH owing to neutralization increases with the increasing C_CaO. However, the type of stabilizer did not significantly affect the relationship between the degree of CO₂ fixation and the degree of neutralization.