Acid Rain Attack on Portland Cementitious Materials in China: Deterioration Process and Corrosion Products

2010 ◽  
Vol 168-170 ◽  
pp. 82-85
Author(s):  
Kai Wang ◽  
Meng Cheng Chen ◽  
Li Xie
Keyword(s):  
Acid Rain ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Corrosion Layer ◽  
Simulated Acid Rain ◽  
Corrosion Products ◽  
Corrosion Mechanism ◽  
Cement Pastes ◽  
Alumina Gel ◽  
Deterioration Process

A research program was undertaken to discover the corrosion mechanism of portland cementitious materials to acid rain attack in China. The deterioration process and corrosion products of hardened ordinary portland cement pastes in pH 2 simulated acid rain solution were analyzed by XRD and BSE. The results indicate that the destruction of hardened portland cementitious materials by acid rain attack in China is predominantly due to the coordinated effect of H+ and SO42- of acid rain solution, and gradually occurs from the surface to the interior of materials. The corrosion products are mainly a white mushy mixture consisting of silica gel (SiO2•nH2O), alumina gel (Al2O3•nH2O) and dihydrate gypsum (CaSO4•2H2O) crystal. During the process of acid rain attack, the deteriorated specimen can be divided into corrosion layer, affected layer and unaffected layer.

Study of Electrochemical Behavior of the Transmission Tower Galvanized Layer in Simulated Acid Rain Solution

2013 ◽  
Vol 361-363 ◽  
pp. 1042-1045
Author(s):  
Hua Ling Deng ◽  
Qi Lei Sun
Keyword(s):  
Acid Rain ◽  
Electrochemical Behavior ◽  
Electrochemical Impedance ◽  
Ph Value ◽  
Low Ph ◽  
Simulated Acid Rain ◽  
Corrosion Products ◽  
Precipitation Process ◽  
Layer Surface ◽  
Transmission Tower

Using electrochemical impedance spectroscopy (EIS), polarization curve and X-ray diffraction technique, electrochemical behavior of the transmission tower material Q460 galvanized layer was studied in simulated acid rain solution. The results show that: galvanized layers take place local corrosion in simulated acid rain solution, the corrosion products will fill the hole, and cover on galvanized layer surface, the generated white corrosion products mainly ZnSO4 ·H2O.The current generate in the process of corrosion, galvanized layer surface take place electrochemical corrosion. Galvanized layer solution at pH 2.4 and 3.8 of the simulated acid rain in the corrosion process is controlled by the charge transfer process, with the decrease of solution pH value, the corrosion rate increases. Zinc are more sensitive to H+ in the solution, in low pH value of solution, due to the strong hydrogen precipitation process, the zinc surface adsorption of hydrogen bubble around, its dissolution rate is higher than the surface of the other part of the zinc, namely in low pH value of acid rain solution, H+ by depolarization process not only directly accelerate the corrosion of zinc, can through the strong hydrogen evolution process at the same time accelerate the dissolution of zinc.

Study on Sulphate Resistance of Often-Used Cementitious Material of High Performance Concrete for Marine

2012 ◽  
Vol 450-451 ◽  
pp. 94-101
Author(s):  
Kun Peng Gu ◽  
Cheng Qi Wang
Keyword(s):  
Corrosion Resistance ◽  
Portland Cement ◽  
High Performance ◽  
Ordinary Portland Cement ◽  
High Performance Concrete ◽  
Cementitious Materials ◽  
Resistance Coefficient ◽  
Cementitious Material ◽  
Corrosion Mechanism ◽  
Better Than

Corrosion resistance coefficient and expansion ratio of different cementitious materials are tested under the sulphate corrosion experimental condition, sulphate resistance of often-used cementitious material of high performance concrete for marine is studied and evaluated. The results show that sulphate resistance of portland cement is better than ordinary portland cement, and both of them are low, often-used cementitious material of high performance concrete for marine have certain sulphate resistance, which are better than ordinary portland cement and portland cement, and some of them have strong or very strong sulphate resistance. The evaluation results of the sulphate resistance of often-used cementitious material of high performance concrete for marine are not unanimous completely by corrosion resistance coefficient method and expansion rate method. Sulphate corrosion mechanism of different kinds of cementitious material is analyzed.

Corrosion Mechanism of AM50 Magnesium Alloy in Simulated Acid Rain

2013 ◽  
Vol 3 (1) ◽  
pp. 47-57
Author(s):  
Feng Liu ◽  
Yingwei Song ◽  
Dayong Shan ◽  
En-Hou Han
Keyword(s):  
Magnesium Alloy ◽  
Acid Rain ◽  
Simulated Acid Rain ◽  
Corrosion Mechanism

Effect of Simulated Acid Rain on Gas Exchanges of Three Compositae Invasive Plants

2013 ◽  
Vol 48 (2) ◽  
pp. 160-167
Author(s):  
Song Liying ◽  
Ke Zhanhong ◽  
Sun Lanlan ◽  
Peng Changlian
Keyword(s):  
Acid Rain ◽  
Invasive Plants ◽  
Simulated Acid Rain ◽  
Gas Exchanges

scholarly journals A Review of the Mechanical Properties and Durability of Ecological Concretes in a Cold Climate in Comparison to Standard Ordinary Portland Cement-Based Concrete

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3467
Author(s):  
Ankit Kothari ◽  
Karin Habermehl-Cwirzen ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Carbon Dioxide ◽  
Portland Cement ◽  
Ordinary Portland Cement ◽  
Cementitious Materials ◽  
Cold Climate ◽  
Supplementary Cementitious Materials ◽  
Short Exposure ◽  
Chemical Admixtures ◽  
Composite Cements ◽  
Alkali Activated

Most of the currently used concretes are based on ordinary Portland cement (OPC) which results in a high carbon dioxide footprint and thus has a negative environmental impact. Replacing OPCs, partially or fully by ecological binders, i.e., supplementary cementitious materials (SCMs) or alternative binders, aims to decrease the carbon dioxide footprint. Both solutions introduced a number of technological problems, including their performance, when exposed to low, subfreezing temperatures during casting operations and the hardening stage. This review indicates that the present knowledge enables the production of OPC-based concretes at temperatures as low as −10 °C, without the need of any additional measures such as, e.g., heating. Conversely, composite cements containing SCMs or alkali-activated binders (AACs) showed mixed performances, ranging from inferior to superior in comparison with OPC. Most concretes based on composite cements require pre/post heat curing or only a short exposure to sub-zero temperatures. At the same time, certain alkali-activated systems performed very well even at −20 °C without the need for additional curing. Chemical admixtures developed for OPC do not always perform well in other binder systems. This review showed that there is only a limited knowledge on how chemical admixtures work in ecological concretes at low temperatures and how to accelerate the hydration rate of composite cements containing high amounts of SCMs or AACs, when these are cured at subfreezing temperatures.

scholarly journals New Approach for the Determination of Radiological Parameters on Hardened Cement Pastes with Coal Fly Ash

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 475
Author(s):  
Ana María Moreno de los Reyes ◽  
José Antonio Suárez-Navarro ◽  
Maria del Mar Alonso ◽  
Catalina Gascó ◽  
Isabel Sobrados ◽  
...  
Keyword(s):  
Fly Ash ◽  
Activity Concentration ◽  
Gamma Ray ◽  
Coal Fly Ash ◽  
Cementitious Materials ◽  
New Method ◽  
Supplementary Cementitious Materials ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Activity Concentrations

Supplementary cementitious materials (SCMs) in industrial waste and by-products are routinely used to mitigate the adverse environmental effects of, and lower the energy consumption associated with, ordinary Portland cement (OPC) manufacture. Many such SCMs, such as type F coal fly ash (FA), are naturally occurring radioactive materials (NORMs). 226Ra, 232Th and 40K radionuclide activity concentration, information needed to determine what is known as the gamma-ray activity concentration index (ACI), is normally collected from ground cement samples. The present study aims to validate a new method for calculating the ACI from measurements made on unground 5 cm cubic specimens. Mechanical, mineralogical and radiological characterisation of 28-day OPC + FA pastes (bearing up to 30 wt % FA) were characterised to determine their mechanical, mineralogical and radiological properties. The activity concentrations found for 226Ra, 212Pb, 232Th and 40K in hardened, intact 5 cm cubic specimens were also statistically equal to the theoretically calculated values and to the same materials when ground to a powder. These findings consequently validated the new method. The possibility of determining the activity concentrations needed to establish the ACI for cement-based materials on unground samples introduces a new field of radiological research on actual cement, mortar and concrete materials.

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