Durability of concrete containing blended cements in harsh marine environments: 18 years exposure study

2021 ◽  
Vol 299 ◽  
pp. 123863
Author(s):  
A.A. Ramezanianpour ◽  
A.R. Pourkhorshidi ◽  
J. Sobhani ◽  
F. Moodi
Keyword(s):  
Marine Environments ◽  
Blended Cements ◽  
Exposure Study ◽  
Durability Of Concrete

scholarly journals Assessment of Corrosion Performance of Steel Rebar in Snail Shell Ash Blended Cements under Marine Environments

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7286
Author(s):  
Raghav Muralidharan ◽  
Karthick Subbiah ◽  
Taejoon Park ◽  
Han-Seung Lee
Keyword(s):  
Fourier Transforms ◽  
Decomposition Methods ◽  
Marine Environments ◽  
Corrosion Performance ◽  
X Ray Diffraction ◽  
Snail Shell ◽  
X Ray ◽  
Blended Cements ◽  
Steel Rebar ◽  
Fourier Transforms Infrared Spectroscopy

An attempt has been made on a constructive approach to evaluate the performance of snail shell ash (SSA) for its corrosion performance under marine environments. Corrosion performance of steel rebar in chloride-contaminated SSA with (0% to 50%) replacement levels of cement extract medium was examined through electrochemical and weight loss techniques. Initially, snail shell powder (SSP) is made by pulverizing and subsequently SSA is by thermal decomposition methods. Both SSP and SSA were characterized by X-ray diffraction, Fourier transforms infrared spectroscopy, scanning electron microscopy, and energy dispersion X-ray spectroscopy. Concrete cubes with 0% to 50% replacement levels of cement by SSA were evaluated for their mechanical properties. A critical level of 20 to 30% SSA improved both corrosion resistance and strength of concrete. Extrapolation modeling for the strength and corrosion rate with respect to later age were made. SSA is a suitable replacement material for natural limestone in cement productions.

scholarly journals Experimental Study on the Strength and Durability for Slag Cement Mortar with Bentonite

2021 ◽  
Vol 11 (3) ◽  
pp. 1176
Author(s):  
Hsien Hua Lee ◽  
Chung-Wei Wang ◽  
Pei-Yin Chung
Keyword(s):  
Construction Projects ◽  
Moisture Absorption ◽  
Cement Mortar ◽  
Pozzolanic Reaction ◽  
Marine Environments ◽  
Slag Cement ◽  
Chloride Permeability ◽  
Reinforced Steel ◽  
Strength And Durability ◽  
Durability Of Concrete

This study focused on improving the durability of concrete infrastructures located in marine environments. When structures made of concrete are exposed to a marine environment, the combined effects of mechanical and chemical actions, such as attacks from sulfate and chloride, may deteriorate the material, then cause corrosion of the embedded reinforced steel bars, and finally result in shortening of the service life of the structure. Therefore, proposed in this work is a method mainly focused on improving the strength and durability of concrete composed with slag cement as a binder, which due to its pozzolanic reaction is commonly applied in construction projects in marine environments. The durability of slag cement mortar can be improved through the application of bentonite material by utilizing bentonite’s very finely divided form and its reactivity to sulfate so that the larger capillary pores in concrete can be filled. It was found that a slight (approximately 0.25%) replacement of slag cement with bentonite material effectively improved the durability of the slag cement mortar in terms of moisture absorption, compressive strength, and weight loss after a sulfate resistance test and the evaluation for chloride permeability.

Scanning Electron Microscopy and x-ray analysis of microparticles and early hydration effects

1995 ◽  
Vol 53 ◽  
pp. 692-693
Author(s):  
Yun Lu ◽  
David C. Joy
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
High Resolution ◽  
Morphological Development ◽  
Early Hydration ◽  
X Ray ◽  
Blended Cements ◽  
Powder Particles ◽  
Chemical Wastes ◽  
Scanning Electron

High resolution scanning electron microscopy (SEM) and energy dispersive x-ray analysis (EDXA) were performed to investigate microparticles in blended cements and their hydration products containing sodium-rich chemical wastes. The physical appearance of powder particles and the morphological development at different hydration stages were characterized by using high resolution SEM Hitachi S-900 and by SEM S-800 with a EDX spectrometer. Microparticles were dispersed on the sample holder and glued by 1% palomino solution. Hydrated bulk samples were dehydrated by acetone and mounted on the holder by silver paste. Both fracture surfaces and flat cutting sections of hydrating samples were prepared and examined. Some specimens were coated with an 3 nm thick Au-Pd or Cr layer to provide good conducting surfaces. For high resolution SEM S-900 observations the accelerating voltage of electrons was 1-2 KeV to protect the electron charging. Microchemical analyses were carried out by S800/EDS equipped with a LINK detector of take-off angle =40°.

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