Changes of pore structure and chloride content in cement pastes after pore solution expression

2020 ◽  
Vol 106 ◽  
pp. 103465 ◽  
Author(s):  
Xiang Hu ◽  
Caijun Shi ◽  
Qiang Yuan ◽  
Jian Zhang ◽  
Geert De Schutter
Keyword(s):  
Pore Structure ◽  
Pore Solution ◽  
Chloride Content ◽  
Cement Pastes

Hydration Performance and Pore Structure of Fly Ash-Cement Pastes

2012 ◽  
Vol 204-208 ◽  
pp. 3867-3871 ◽  
Author(s):  
Xiang Li ◽  
Yun Dong ◽  
Hua Quan Yang
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Pore Solution ◽  
Ex Situ ◽  
Replacement Ratio ◽  
Cement Pastes ◽  
Binder Ratio ◽  
Very High ◽  
Reaction Degree ◽  
Curing Age

The hydration performance and pore structure of fly ash-cement (FC) pastes were investigated by means of XRD, TG, ex-situ leaching (ESL) and MIP. The results reveal that the influence of curing age to the kinds of hydration products of FC pastes is unconspicuous. As the content of fly ash increase, the Ca(OH)2 content decrease gradually. However, the content of Ca(OH)2 left in every paste is almost constant after 28d, regardless of the replacement ratio of fly ash and water-binder ratio. The decline of alkalinity of pore solution is not endless, even though the contents of fly ash in FC pastes is very high(65%).The incorporation of fly ash in proper ratios could increase the ratio of harmless pores and improve the microstructure of the FC pastes. Ca(OH)2 was not consumed heavily or exhausted when cementitious material was hydrated due to the low reaction degree of fly ash.

Assessment of Anhydrous Ethanol Extraction to Determine the Ionic Concentration of Hardened Cement Pastes

2010 ◽  
Vol 177 ◽  
pp. 506-509 ◽  
Author(s):  
Man Jian Wu ◽  
Wu Yao ◽  
Wei Wang ◽  
Yong Qi Wei
Keyword(s):  
Pore Solution ◽  
Ph Value ◽  
Ionic Concentration ◽  
Anhydrous Ethanol ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Ethanol Extraction ◽  
Alkali Ions ◽  
Ph Values ◽  
Hardened Cement Pastes

A new method involving the extraction of various ions from hardened cement pastes by anhydrous ethanol is presented to determine the pH value and ionic concentration during the first 28 days. The volume content of pore solution extracted by ethanol in the leachate reached 12% or above and the pH values calculated by alkali ions are more than 12, even up to 12.73. The results were compared with those from parallel, conventional pore water expression experiments. All of these comparisons verified the feasibility of the proposed method. However, the application of this method to pore solution analysis needs further improvement.

scholarly journals Detection of the critical chloride threshold of carbon steel rebar in synthetic concrete pore solutions.

2019 ◽  
Vol 3 ◽  
pp. 75-83 ◽  
Author(s):  
Ibrahim Gbolahan Ogunsanya ◽  
Carolyn M. Hansson
Keyword(s):  
Carbon Steel ◽  
Pore Solution ◽  
Input Parameter ◽  
Highway Bridges ◽  
Chloride Content ◽  
Reinforcing Bars ◽  
Current Standard ◽  
Existing Structures ◽  
Essential Input ◽  
The Many

Knowledge of the critical chloride content in concrete required to initiate corrosion of reinforcing steel is economically beneficial for the assessment and maintenance of existing structures. Also, many building codes now specify a service life of 75 – 100 years for highway bridges and the critical chloride content is an essential input parameter in the models used in design of structures.  There have been numerous studies aimed at determining this parameter but there is no consensus because of the many factors influencing the corrosion.  The current standard methods, e.g. ASTM G109, require many weeks or months of testing and are not appropriate for testing large numbers of specimens in different conditions. This project has demonstrated that a fairly rapid potentiodynamic polarization technique can be applied to carbon steel reinforcing bars in synthetic concrete pore solution to determine the critical value, as illustrated in the figure. The importance of selecting the appropriate synthetic concrete pore solution for this application is demonstrated by the different critical values obtained for different solutions.  The success of this test will allow the influence of different reinforcing alloys and different cementitious material mixes on the critical chloride content to be determined in a reasonable period of time.  

Device for Pore Solution Extraction from Cement-Based Materials and its Application

2016 ◽  
Vol 680 ◽  
pp. 365-369
Author(s):  
Jian Liang Zhang ◽  
An Qun Lu ◽  
Hua Li ◽  
Rui Wang ◽  
Wen Bin Wang ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Pore Solution ◽  
Early Age ◽  
Cement Pastes ◽  
Cement Based Materials ◽  
Different Ages ◽  
Low Rate ◽  
Relevant Factors

In this paper, a device for pore solution extraction from cement-based materials was presented, The relevant Factors of Efficiency of Pore Solution Extraction and the effects of squeezing pressures on the chemical concentrations of pore solutions were studied. The results shows, the efficiency of pore solution extraction can be effected by pressure values, squeezing duration, pressure maintaining time; A low rate of pressures loading is suitable for early-age cement pastes, and long-term samples can take larger rate; 30 minutes loading time can be adopted for specimens with all the different ages; no significant differences were observed regarding the chemical composition (Na and K) of the pore solution extracted between 300 and 900MPa.

Pore structure characterization of cement pastes blended with high-volume fly-ash

2012 ◽  
Vol 42 (1) ◽  
pp. 194-204 ◽  
Author(s):  
Qiang Zeng ◽  
Kefei Li ◽  
Teddy Fen-chong ◽  
Patrick Dangla
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
High Volume ◽  
Structure Characterization ◽  
Cement Pastes ◽  
High Volume Fly Ash
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