Monitoring of steel corrosion and cracking in cement paste exposed to combined sulfate–chloride attack with X-ray microtomography

The X ray computed tomography (X-CT) was applied to test the cracking resistance of cement paste, and the hydration process was monitored to study the effect of fly ash on the early age cracking performance. The results showed that the hydration heat reduced with the increase of fly ash under the same water-cement ratio. Within 24h, the porosity increased with time. The addition of fly ash increased the proportion of large holes and then changed the internal stress state. Using X-CT test method and by comparing the number of cracks, the sample with 20% FA was found to have the most serious cracks, whereas the sample with 30% FA had the best crack resistance.

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The Specific Surface of Hardened Portland Cement Paste as Measured by Low-Angle X-Ray Scattering

10.5703/1288284313854 ◽

1973 ◽

Cited By ~ 1

Author(s):

Douglas Windslow

Keyword(s):

Portland Cement ◽

Specific Surface ◽

Cement Paste ◽

X Ray ◽

X Ray Scattering ◽

Portland Cement Paste ◽

Ray Scattering

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Effect of Waste Clay Brick Powder on Physical and Mechanical Properties of Cement Paste

The Open Civil Engineering Journal ◽

10.2174/1874149502115010370 ◽

2021 ◽

Vol 15 (1) ◽

pp. 370-380

Author(s):

David Sinkhonde ◽

Richard Ocharo Onchiri ◽

Walter Odhiambo Oyawa ◽

John Nyiro Mwero

Keyword(s):

Compressive Strength ◽

Cement Paste ◽

Setting Time ◽

Partial Replacement ◽

Clay Brick ◽

X Ray ◽

Cement Replacement ◽

Clay Bricks ◽

Brick Powder ◽

Scanning Electron

Background: Investigations on the use of waste clay brick powder in concrete have been extensively conducted, but the analysis of waste clay brick powder effects on cement paste is limited. Materials and Methods: This paper discusses the effects of waste clay brick powder on cement paste. Fragmented clay bricks were grounded in the laboratory using a ball mill and incorporated into cementitious mixes as partial replacement of Ordinary Portland Cement. Workability, consistency, setting time, density and compressive strength properties of paste mixes were investigated to better understand the impact of waste clay brick powder on the cementitious paste. Four cement replacement levels of 2.5%, 5%, 7.5% and 10% were evaluated in comparison with the control paste. The chemical and mineral compositions were evaluated using X-Ray Fluorescence and X-Ray Diffractometer, respectively. The morphology of cement and waste clay brick powder was examined using a scanning electron microscope. Results: The investigation of workability exhibited a reduction of slump attributed to the significant addition of waste clay brick powder into the cementitious mixes, and it was concluded that waste clay brick powder did not significantly influence the density of the mixes. In comparison with the control paste, increased values of consistency and setting time of cement paste containing waste clay brick powder confirmed the information available in the literature. Conclusion: Although waste clay brick powder decreased the compressive strength of cement paste, 5% partial cement replacement with waste clay brick powder was established as an optimum percentage for specimens containing waste clay brick powder following curing periods of 7 and 28 days. Findings of chemical composition, mineral composition and scanning electron microscopy of waste clay brick powder demonstrated that when finely ground, fragmented clay bricks can be used in concrete as a pozzolanic material.

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NATURAL CORROSION INHIBITORS FOR STEEL REINFORCEMENT IN CONCRETE — A REVIEW

Surface Review and Letters ◽

10.1142/s0218625x15500407 ◽

2015 ◽

Vol 22 (03) ◽

pp. 1550040 ◽

Cited By ~ 15

Author(s):

PANDIAN BOTHI RAJA ◽

SEYEDMOJTABA GHOREISHIAMIRI ◽

MOHAMMAD ISMAIL

Keyword(s):

Reinforced Concrete ◽

Corrosion Inhibitors ◽

Construction Materials ◽

Steel Corrosion ◽

Vital Role ◽

Prevention Measures ◽

Main Culprit ◽

Chloride Attack ◽

Reinforced Steel ◽

Metal Protection

Reinforced concrete is one of the widely used construction materials for bridges, buildings, platforms and tunnels. Though reinforced concrete is capable of withstanding a large range of severe environments including marine, industrial and alpine conditions, there are still a large number of failures in concrete structures for many reasons. Either carbonation or chloride attack is the main culprit which is due to depassivation of reinforced steel and subsequently leads to rapid steel corrosion. Among many corrosion prevention measures, application of corrosion inhibitors play a vital role in metal protection. Numerous range of corrosion inhibitors were reported for concrete protection that were also used commercially in industries. This review summarizes the application of natural products as corrosion inhibitors for concrete protection and also scrutinizes various factors influencing its applicability.

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A study of the corrosion of polymethyl methacrylate coated rebar using glancing angle X-ray absorption near edge spectroscopy

CORROSION ◽

10.5006/3912 ◽

2021 ◽

Author(s):

Arthur Situm ◽

Xiaoxuan Guo ◽

Burke Barlow ◽

Bao Guo ◽

Ian Burgess ◽

...

Keyword(s):

Polymethyl Methacrylate ◽

Polymer Coating ◽

Steel Corrosion ◽

Corrosion Products ◽

Thin Layers ◽

Fluorescence Signal ◽

X Rays ◽

X Ray ◽

Glancing Angle ◽

X Ray Absorption

Polymer coatings can be used to mitigate the corrosion of steel in high chloride environments. Obtaining speciation information from thin corrosion layers can be important for understanding corrosion mechanisms, including polymer coating failure. This study outlines the effectiveness of collecting glancing angle X-ray absorption near edge spectroscopy (GA-XANES) spectra at the Fe K-edge to obtain chemical speciation information at the polymer-steel interface without removal of the polymer film. The depth of penetration of the incident X-rays can be altered by changing the incidence angle, allowing for more fluorescence signal from corrosion products to be detected relative to the Fe metal fluorescence signal in GA-XANES spectra. This study demonstrates the use of GA-XANES to study thin layers of steel corrosion and obtain depth profile information of steel corrosion products beneath a polymethyl methacrylate polymer coating.

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Micromechanical modelling of deformation and fracture of hydrating cement paste using X-ray computed tomography characterisation

Composites Part B Engineering ◽

10.1016/j.compositesb.2015.11.007 ◽

2016 ◽

Vol 88 ◽

pp. 64-72 ◽

Cited By ~ 46

Author(s):

Mingzhong Zhang ◽

Andrey P. Jivkov

Keyword(s):

Computed Tomography ◽

Cement Paste ◽

Micromechanical Modelling ◽

X Ray ◽

Deformation And Fracture ◽

X Ray Computed

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

MRS Proceedings ◽

10.1557/proc-370-77 ◽

1994 ◽

Vol 370 ◽

Cited By ~ 14

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.

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Sustainable Nanopozzolan Modified Cement: Characterizations and Morphology of Calcium Silicate Hydrate during Hydration

Journal of Nanomaterials ◽

10.1155/2015/713258 ◽

2015 ◽

Vol 2015 ◽

pp. 1-6 ◽

Cited By ~ 5

Author(s):

N. Mohamed Sutan ◽

I. Yakub ◽

M. S. Jaafar ◽

K. A. Matori ◽

S. K. Sahari

Keyword(s):

Cement Paste ◽

Physical And Mechanical Properties ◽

X Ray Diffraction ◽

X Ray ◽

Pozzolanic Reactivity ◽

Synthetic Materials ◽

Water To Cement Ratio ◽

Mechanical Properties Characterization ◽

Micro Silica ◽

By Products

There are environmental and sustainable benefits of partially replacing cement with industrial by-products or synthetic materials in cement based products. Since microstructural behaviours of cement based products are the crucial parameters that govern their sustainability and durability, this study investigates the microstructural comparison between two different types of cement replacements as nanopozzolan modified cement (NPMC) in cement based product by focusing on the evidence of pozzolanic reactivity in corroboration with physical and mechanical properties. Characterization and morphology techniques using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDS), and scanning electron microscopy (SEM) were carried out to assess the pozzolanic reactivity of cement paste modified with the combination of nano- and micro silica as NPMC in comparison to unmodified cement paste (UCP) of 0.5 water to cement ratio (w/c). Results were then substantiated with compressive strength (CS) results as mechanical property. Results of this study showed clear evidence of pozzolanicity for all samples with varying reactivity with NPMC being the most reactive.

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