scholarly journals Effect of Supplemental Cementitious Materials on Electric Conductivity and Chloride Ingress of Hardened Cement Paste

◽  
2016 ◽  
Author(s):  
Kiyfomi Kurumisawa ◽  
◽  
Toyoharu Nawa ◽  
Keyword(s):  
Electric Conductivity ◽  
Cement Paste ◽  
Cementitious Materials ◽  
Hardened Cement ◽  
Chloride Ingress ◽  
Hardened Cement Paste

scholarly journals Alteration of vitrified intermediate level nuclear waste in alkaline media: effects of cementitious materials, pH and temperature

RSC Advances ◽  
2018 ◽  
Vol 8 (66) ◽  
pp. 37665-37680 ◽  
Author(s):  
Tomo Suzuki-Muresan ◽  
A. Abdelouas ◽  
C. Landesman ◽  
A. Ait-Chaou ◽  
Y. El Mendili ◽  
...  
Keyword(s):  
Cement Paste ◽  
Nuclear Waste ◽  
Media Effects ◽  
Cementitious Materials ◽  
Intermediate Level ◽  
Alkaline Media ◽  
Hardened Cement ◽  
Hardened Cement Paste

Alteration experiments involving intermediate level nuclear waste (ILW) glass in contact with hardened cement paste (HCP) were performed to assess its behavior under simulated repository conditions.

scholarly journals Immobilization of radioactive waste in cement: Iodine binding by cementitious materials under highly alkaline conditions

2015 ◽  
Vol 55 (1) ◽  
Author(s):  
Rūta Druteikienė ◽  
Justina Šapolaitė ◽  
Žilvinas Ežerinskis ◽  
Evaldas Naujalis ◽  
Andrius Puzas
Keyword(s):  
Radioactive Waste ◽  
Distribution Coefficient ◽  
Cement Paste ◽  
Chemical Speciation ◽  
Cementitious Materials ◽  
Batch Experiment ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Strong Binding ◽  
Alkaline Conditions

This work is directed to assess iodine interactions with hardened cement paste (HCP) under highly alkaline conditions (pH > 12) with/without a reductant. For this purpose, a series of Kd (distribution coefficient) experiments using 127I as a tracer were performed. The Kd values of iodine were in the order of 172–1095 mL g–1 in the batch experiment without a reductant, and in the order of 83–92 mL g–1 in the experiment with a reductant. The percentage of iodine leached out from HCP throughout the experiment suggested its very strong binding with cementitious materials. The obtained results allow supposing that chemical speciation of iodine has influence on the interaction of iodine with HCP under highly alkaline conditions.

scholarly journals Hydration characteristics and structure formation of cement pastes containing metakaolin

2018 ◽  
Vol 149 ◽  
pp. 01013 ◽  
Author(s):  
Leonid Dvorkin ◽  
Nataliya Lushnikova ◽  
Oleksandr Bezusyak ◽  
Mohammed Sonebi ◽  
Jamal Khatib
Keyword(s):  
Pore Structure ◽  
Cement Paste ◽  
Average Diameter ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Mineral Admixtures ◽  
Hardened Cement ◽  
Initial Structure ◽  
Hardened Cement Paste ◽  
Cement Pastes

Metakaolin (MK) is one of the most effective mineral admixtures for cement-based composites. The deposits of kaolin clays are wide-spread in the world. Metakaolin is comparable to silica fume as an active mineral admixture for cement-based composites. In this paper, the rheological and mechanical properties of cement paste containing metakaolin are investigated. The effect of MK is more evident at “tight” hydration conditions within mixtures with low water-cement ratio, provided by application of superplasticizers. The cement is replaced with 0 to 15% metakaolin, and superplasticizer content ranged from 0 to 1.5% by weight of cementitious materials (i.e. cement and metakaolin). An equation is derived to describe the relationship between the metakaolin and superplasticizer content and consistency of pastes. There is a linear dependence between metakalolin content and water demand. Second-degree polynomial describe the influence of superplasticizer content. The application of SP and MK may produce cement-water suspensions with water-retaining capacity at 50-70% higher than control suspensions. The investigation of initial structure forming of cement pastes with SP-MK composite admixture indicates the extension of coagulation structure forming phase comparing to the pastes without additives. Crystallization stage was characterized by more intensive strengthening of the paste with SP-MK admixture comparing to the paste without admixtures and paste with SP. Results on the porosity parameters for hardened cement paste indicate a decrease in the average diameter of pores and refinement of pore structure in the presence of metakaolin. A finer pore structure associated with an increase in strength. X-ray analysis data reveal a growing number of small-crystalline low-alkaline calcium hydrosilicates and reducing portlandite content, when MK dosage increases. Scanning electron microscopy (SEM) data confirm, that hardened cement paste containing MK has crystalline structure with dominance of partially crystalized hydrosilicates and gel-like formations.

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