scholarly journals Concrete Deterioration and Floor Heave Due to Biogeochemical Weathering of Underlying Shale

1975 ◽  
Vol 12 (3) ◽  
pp. 372-378 ◽  
Author(s):  
P. E. Grattan-Bellew ◽  
W. J. Eden
Keyword(s):  
Porous Material ◽  
Main Product ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Oxidation Reactions ◽  
Concrete Deterioration ◽  
Weathered Zone ◽  
Sulfur Bacteria ◽  
Basement Floor ◽  
Floor Heave

When the basement floor of a church in the New Edinburgh area of Ottawa heaved, it was discovered that the concrete under the floor had been reduced to a mushy consistency due to attack by sulfate solution formed by the oxidation of pyrite in the underlying shale. Gypsum was the main product in the weathered zone of the shale. It is shown that heaving resulted from the growth of gypsum crystals between the lamellae in the shale. Jarosite, which is formed by a series of oxidation reactions from pyrite, was also found in the weathered shale. Some oxidation reactions occur only in the presence of sulfur bacteria. The cementitious portion of the concrete was leached out by acid, leaving a weak porous material. The importance of safeguarding concrete in contact with potentially expansive shales from sulfate attack is emphasized.

scholarly journals Experiment Analysis of Concrete’s Mechanical Property Deterioration Suffered Sulfate Attack and Drying-Wetting Cycles

2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Wei Tian ◽  
Nv Han
Keyword(s):  
Inductively Coupled Plasma ◽  
Ct Scanning ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Salt Crystallization ◽  
Ct Number ◽  
Inductively Coupled ◽  
Concrete Deterioration ◽  
Deterioration Process ◽  
Expansion Force

The mechanism of concrete deterioration in sodium sulfate solution is investigated. The macroperformance was characterized via its apparent properties, mass loss, and compressive strength. Changes in ions in the solution at different sulfate attack periods were tested by inductively coupled plasma (ICP). The damage evolution law, as well as analysis of the concrete’s meso- and microstructure, was revealed by scanning electron microscope (SEM) and computed tomography (CT) scanning equipment. The results show that the characteristics of concrete differed at each sulfate attack period; the drying-wetting cycles generally accelerated the deterioration process of concrete. In the early sulfate attack period, the pore structure of the concrete was filled with sulfate attack products (e.g., ettringite and gypsum), and its mass and strength increased. The pore size and porosity decreased while the CT number increased. As deterioration progressed, the swelling/expansion force of products and the salt crystallization pressure of sulfate crystals acted on the inner wall of the concrete to accumulate damage and accelerate deterioration. The mass and strength of concrete sharply decreased. The number and volume of pores increased, and the pore grew more quickly resulting in initiation and expansion of microcracks while the CT number decreased.

Simulations on Expansive Strain of Concrete Caused by Ettringite Growth under Sulfate Attack

2011 ◽  
Vol 250-253 ◽  
pp. 1906-1911 ◽  
Author(s):  
Xiao Bao Zuo ◽  
Wei Sun
Keyword(s):  
Sulfate Solution ◽  
Sulfate Attack ◽  
Diffusion Time ◽  
Diffusion Reaction ◽  
Sulfate Ion ◽  
Reaction Equation ◽  
Ettringite Formation ◽  
Sulfate Solutions ◽  
Calcium Aluminates ◽  
Strain Responses

In order to assess theoretically the expansive strain of concrete caused by the ettringite formation and growth under the sulfate attack, some models are proposed to investigate the strain responses of concrete exposed to the sulfate solutions. Firstly, an 1-D nonlinear and nonsteady diffusion-reaction equation of sulfate ion in concrete is proposed; Secondly, based on chemical reactions between sulfate and aluminates in concrete, the expansive strain is obtained due to the ettringite growth resulting in concrete expansion. Thirdly, numerical simulations are carried out to analyze the formation process of the concrete expansive strain under the sulfate solution, and results show that the models can be used to predict the concrete responses with the diffusion time, such as the distribution concentration of sulfate ion, dissipated concentration of the calcium aluminates, expansion strain of concrete due to the formation and growth of ettringite.

Deterioration of concrete containing limestone powder exposed to sulfate attack at ambient temperature

2021 ◽  
Vol 11 (5) ◽  
pp. 724-731
Author(s):  
Hemin Liu ◽  
Qian Huang ◽  
Liang Zhao
Keyword(s):  
Ambient Temperature ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
Adverse Influence ◽  
Powder Content ◽  
Scanning Electron

This study investigates the deterioration of concrete containing limestone powder exposed to sulfate solution under ambient temperature (20~25 °C). Microstructure and mineral phases within the attacked concrete were measured by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). It was found that the addition of limestone powder increased the initial porosity of concrete. Consequently, a larger amount of SO2–4 ions diffused into the concrete containing limestone powder, and their degree of deterioration caused by sulfate attack increased with the increase in limestone powder content. At ambient temperature, gypsum and ettringite were the major attack products, respectively within the surface and nearsurface portions of concrete containing limestone powder, which was consistent with the products of sulfate attack within concrete without limestone powder. Therefore, the type and distribution of the attack products in concrete had not been revised due to the addition of limestone powder. Nevertheless, the adverse influence of limestone powder on the sulfate resistance of concrete, even at ambient temperature, should be considered. Furthermore, effective measures should be implemented to improve the durability of concrete containing limestone powder in this environment.

X-Ray Microtomography of an Astm C109 Mortar Exposed to Sulfate Attack

1994 ◽  
Vol 370 ◽  
Author(s):  
D.P. Bentz ◽  
Nicos. S. Martys ◽  
P. Stutzman ◽  
M. S. Levenson ◽  
E.J. Garboczi ◽  
...  
Keyword(s):  
Cement Paste ◽  
Sodium Sulfate ◽  
Three Dimensional ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Mortar Sample ◽  
Air Voids ◽  
X Ray ◽  
Dimensional Image

AbstractX-ray microtomography can be used to generate three-dimensional 5123 images of random materials at a resolution of a few micrometers per voxel. This technique has been used to obtain an image of an ASTM C109 mortar sample that had been exposed to a sodium sulfate solution. The three-dimensional image clearly shows sand grains, cement paste, air voids, cracks, and needle-like crystals growing in the air voids. Volume fractions of sand and cement paste determined from the image agree well with the known quantities. Implications for the study of microstructure and proposed uses of X-ray microtomography on cement-based composites are discussed.

Experimental Study on Improving Concrete Sulfate Attack Resistance Ability with Silane Impregnation

2013 ◽  
Vol 405-408 ◽  
pp. 2621-2624
Author(s):  
Zhi De Huang
Keyword(s):  
Sulfate Solution ◽  
Hydration Product ◽  
Sulfate Attack ◽  
Cementitious Material ◽  
Material System ◽  
Absorption Test ◽  
Test Results ◽  
Binder Ratio ◽  
Water Absorption Test ◽  
Drying Test

Silane impregnation effects on concrete sulfate attack resistance ability are systemic researched, through forming different cementitious material system and different water cement ratio mortar specimens, treating with silane impregnation and then curing to 14d age naturally, and doing sulfate solution wetting-drying test. Results shows that silane impregnation effect is poor when fly ash amount is large or water gel is relatively low. Through XRD microscopic, the improving sulfate attack resistance ability mechanisms are analyzed from aspect of cementations material hydration product; water-binder ratio effect on silane impregnation is explained by water absorption test.

scholarly journals Damage Evolution of Concrete Exposed to Sulfate Attack Under Drying-Wetting Cycles

2014 ◽  
Vol 8 (1) ◽  
pp. 444-449
Author(s):  
Lei Jiang ◽  
Ditao Niu
Keyword(s):  
Weight Loss ◽  
Compressive Strength ◽  
Layer Thickness ◽  
Damage Evolution ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Damage Mechanism ◽  
Sulfate Attack ◽  
Corrosion Products ◽  
Damage Layer

The damage evolution of concrete subjected to drying-wetting cycles in different concentration of sodium sulfate solution was investigated based on micro and macro-observations. Through the experiment, weight loss, compressive strength loss and the damage layer thickness of concrete were measured after different drying-wetting cycles. The mechanical properties degradation in the damage layer of concrete was also analyzed. Furthermore, the scanning electron microscopy and X-ray diffraction were used to investigate the corrosion products of concrete, and the damage mechanism was also investigated by the modern microanalysis techniques. The test results show that the deterioration degree of physical properties of concrete specimens increases with increasing concentration. Weight loss of specimens caused by sulfate attack is not obvious compared with the other evaluation index. When the damage layer thickness of concrete is thicker as well as the ultrasonic speed is lower, indicating that the deterioration degree of concrete increases, and the compressive strength loss in damage layer is serious. It was also found that the compressive loss of concrete is correspond with the observations for the damage layer thickness. Additionally, the main corrosion products of concrete in sulfate solutions subjected to drying-wetting cycles were confirmed to be ettringite and gypsum, and the quantity of corrosion products formed is proportional to the concentration of the solution.

scholarly journals The Damage of Fly Ash-Slag Concrete under Sustained Loading in Marine Environments

2018 ◽  
Vol 206 ◽  
pp. 02003
Author(s):  
J Gong ◽  
J Cao ◽  
Y F Wang
Keyword(s):  
Elastic Modulus ◽  
Fly Ash ◽  
Compressive Stress ◽  
Damage Model ◽  
Sulfate Solution ◽  
Solution Concentration ◽  
Sulfate Attack ◽  
Multiple Factors ◽  
Sustained Loading ◽  
Engineering Environment

The durability damage of concrete structures in the actual engineering environment is often the result of the interaction of the load and the environment, climate and other multiple factors. In this paper, the test researches were carried out on the concrete mass and dynamic elastic modulus under the effects of sustained loading, sulfate attack and dry-wet circulation, and the test phenomenon and results were discussed and analyzed. Then this paper proposed the durability damage model of the concrete under the effects of sustained loading, sulfate attack and dry-wet circulation considering the compressive stress level, the sulfate solution concentration and the age of corrosion as test factors, and the rationality of the model was discussed.

Long-term sulfate attack on recycled aggregate concrete immersed in sodium sulfate solution for 10 years

2020 ◽  
Vol 70 (337) ◽  
pp. 212
Author(s):  
L. R. Santillán ◽  
F. Locati ◽  
Y. A. Villagrán-Zaccardi ◽  
C. J. Zega
Keyword(s):  
Sodium Sulfate ◽  
Fluorescent Microscopy ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Sodium Sulfate Solution ◽  
Microscopy Image

The effect of recycled concrete aggregate (RCA) on concrete performance against external sulfate attack (ESA) is not yet fully known. In this paper, recycled aggregate concretes (RAC) with 0, 50, 75 and 100% of RCA contents were evaluated after 10 years of exposure immersed in 50g/l sodium sulfate solution. Sulfate ingress profiles were obtained by wet chemical analyses and FRX. Also, the mineralogy of the ingress profile was evaluated by thermogravimetric analyses. Finally, microcracking development in samples was evaluated by optical fluorescent microscopy image analysis. Although RAC showed a slight increase in sulfate ingress, due to its higher porosity (about 30% higher SO3 content near the surface for 50% or higher replacement ratio than control concrete), a dense new matrix still allows a good performance of RAC to external sulfate attack with even 100% RCA content.

scholarly journals The Effect of Sulfate Attack on Physical Properties of Concrete

2021 ◽  
Vol 10 (2) ◽  
pp. 21-27
Author(s):  
Pooja Kanaujia ◽  
◽  
Rajiv Banerjee ◽  
Syed Mohammad Ashraf Husain ◽  
Sabih Ahmed ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Experimental Studies ◽  
Sulfate Solution ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Mold Growth ◽  
Concrete Blocks ◽  
Weight Analysis ◽  
Density Analysis

The effects of different concentrations of sulfate for erosion age on compressive strength, flexural strength, weight analysis, density loss and visual appearances for concrete specimens of different grades were investigated. Experimental studies were carried out on different grades of concrete (M-25, M-30 and M-35). Concrete specimens were immersed in different concentration of sulfate solution i.e. 4.0pH, 5.0pH and 6.0pH. Reduction in compressive strength loss was noticed when the grade of concrete is increased from M-25 to M35. The results of weight analysis and density analysis also confirm the compressive strength loss and flexural strength. Discoloration of concrete was noticed on the concrete blocks when left immersed in sulfate solution at 4.0pH, 5.0pH and 6.0pH for 75days and 90days. It appeared like flakes of concrete and resembled like mold growth.

scholarly journals Influence of Cement Type and Water-to-Cement Ratio on the Formation of Thaumasite

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Ailian Zhang ◽  
Linchun Zhang
Keyword(s):  
Portland Cement ◽  
Cement Mortar ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Visual Appearance ◽  
Cement Ratio ◽  
Water To Cement Ratio

Cement mortar prisms were prepared with three different cement types and different water-to-cement ratios plus 30% mass of limestone filler. After 28 days of curing in water at room temperature, these samples were submerged in 2% magnesium sulfate solution at 5°C and the visual appearance and strength development for every mortar were measured at intervals up to 1 year. Samples selected from the surface of prisms after 1-year immersion were examined by X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results show that mortars with sulfate resisting Portland cement (SRC) or sulphoaluminate cement (SAC) underwent weaker degradation due to the thaumasite form of sulfate attack than mortars with ordinary Portland cement (OPC). A lower water-to-cement ratio leads to better resistance to the thaumasite form of sulfate attack of the cement mortar. A great deal of thaumasite or thaumasite-containing materials formed in the OPC mortar, and a trace of thaumasite can also be detected in SRC and SAC mortars. Therefore, the thaumasite form of sulfate attack can be alleviated but cannot be avoided by the use of SAC or SRC.

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