Effect of hydrothermal curing on the hydration characteristics of artificial pozzolanic cement pastes placed in closed system

2014 ◽  
Vol 96 ◽  
pp. 110-115 ◽  
Author(s):  
M.R. Shatat
Keyword(s):  
Closed System ◽  
Cement Pastes ◽  
Hydrothermal Curing ◽  
Pozzolanic Cement ◽  
Hydration Characteristics

scholarly journals Residual Capability of Alkali Binding by Hydrated Pozzolanic Cements in Long-Service Concrete Structures

2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Mario Berra ◽  
Teresa Mangialardi ◽  
Antonio Evangelista Paolini
Keyword(s):  
Concrete Structures ◽  
Test Results ◽  
Cement Pastes ◽  
Experimental Procedure ◽  
Accelerated Curing ◽  
Alkali Aggregate Reaction ◽  
Simple Mass ◽  
Pore Liquid ◽  
Pozzolanic Cement

An experimental procedure was developed and applied to cement pastes made with two different pozzolanic cements (CEM IV/B (P) and CEM IV/B (V)) in order to ascertain the existence of a residual capability of alkali binding by long-term hydrated pozzolanic cements and, at the same time, to evaluate the alkali retention capability and the concentration of OH− ions in the pore solution of such cementitious matrices. The developed procedure consisted of accelerated curing of cement paste specimens (150 days at 60°C and 100% RH), subsequent leaching tests at 60°C for 30 days by using deionized water or basic solutions (NaOH or KOH at different concentrations) as leaching media, and correlation of the leaching test results with a simple mass balance equation for sodium and potassium ions. The developed procedure was found to be appropriate for evaluating both the pore liquid alkalinity and the alkali retention capability by long-term hydrated pozzolanic cement pastes. A residual capability of alkali binding was also identified for both tested pozzolanic cements, thus indicating their potential ability to prevent (CEM IV/B (V)) or minimize (CEM IV/B (P)) the risk of deleterious expansion associated with alkali-aggregate reaction in long-service concrete structures, like concrete dams.

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):  
Structure Formation ◽  
Cement Pastes ◽  
Hydration Characteristics

Immobilization of Co (II) Ions in Cement Pastes and Their Effects on the Hydration Characteristics

2011 ◽  
Vol 27 (1) ◽  
pp. 74-80 ◽  
Author(s):  
Eisa Hekal ◽  
Essam Kishar ◽  
Wafaa Hegazi ◽  
Maha Mohamed
Keyword(s):  
Cement Pastes ◽  
Hydration Characteristics

Effects of Nanosilica as Suspensions on the Hydration and the Microstructure of Hardened Cement Paste

2020 ◽  
pp. 036119812096795
Author(s):  
Dulani P. A. Kodippili ◽  
Robin A. L. Drew ◽  
Michelle R. Nokken
Keyword(s):  
Pore Size ◽  
Isothermal Calorimetry ◽  
Hardened Cement ◽  
Cement Pastes ◽  
Production Methods ◽  
Beneficial Effects ◽  
Agglomeration Of Nanoparticles ◽  
Calorimetric Studies ◽  
Hydration Characteristics ◽  
Insight Into

Nanosilica (NS) has shown significant beneficial effects on concrete. However, the utilization of NS to achieve its maximum benefits is limited by the agglomeration of nanoparticles, which is associated with production methods and the method of NS dispersion in concrete. In this study, the effects of the utilization of NS as a suspension in calcium hydroxide (CH) on the hydration characteristics and the microstructure of the cement pastes were investigated with different levels of cement replacements (1%, 2%, 4%, and 6% NS) at 2, 7, and 28 days. The hydration of the cement pastes was investigated by isothermal calorimetry, and the measurement of CH content by thermogravimetry. The microstructures were analyzed by scanning electron microscopy and by energy dispersive X-ray spectroscopic mapping. The microstructure of the pastes was characterized by analyzing the pore size and the pore size distribution using mercury intrusion porosimetry (MIP). The calorimetric studies indicated that the replacing cement by NS derived by this method leads to faster hydration up to 4% replacement. The CH contents could be reduced by the incorporation of NS. The pore structures revealed that the pastes with NS had become comparably denser than the pastes without NS. A positive insight into the durability characteristics was shown by the results of the MIP when using NS as suspensions.

Microstructure and Porosity of Metakaolin Blended Cements

1988 ◽  
Vol 136 ◽  
Author(s):  
P. Bredy ◽  
M. Chabannet ◽  
J. Pera
Keyword(s):  
Compressive Strength ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Size Distribution ◽  
Hydrated Cement ◽  
Cement Pastes ◽  
Blended Cements ◽  
Mercury Intrusion ◽  
Pozzolanic Cement

ABSTRACTFive compositions with 10% to 50% metakaolin for cement substitution were studied. The rate of hydration was studied from the compressive strength after up to 6 months of curing and from the hydrates formed (DTA-XRD). The metakaolin addition considerably reduced portlandite content in the hydrated cement and contributed to the formation of hydrated gehlenite which is not present in OPC paste. The microstructure study (SEM) shows that pozzolanic cement pastes were less crystallized than plain pastes. Mercury intrusion was used to measure porosity of hydrated cement pastes. The porosity with blended cements was higher than that with OPC, except for 10 and 20% metakaolin substitution. Evolution of the pore size distribution was studied: the pozzolanic pastes enhance small diameters.

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