Effect of pore solution calcium and substrate calcium on PMMA/cement paste interface during early stages of hydration

2020 ◽  
Vol 103 (8) ◽  
pp. 4664-4677
Author(s):  
Ashwin Konanur Nagesh ◽  
Nirrupama Kamala Ilango ◽  
Aleena Alex ◽  
Pijush Ghosh
Keyword(s):  
Cement Paste ◽  
Pore Solution ◽  
Early Stages ◽  
Pmma Cement

Simple Approach for Computing Chloride Diffusivity of (Non)Carbonated Concrete

2008 ◽  
Vol 385-387 ◽  
pp. 281-284 ◽  
Author(s):  
In Seok Yoon
Keyword(s):  
Experimental Data ◽  
Structural Properties ◽  
Cement Paste ◽  
Scientific Knowledge ◽  
Pore Solution ◽  
Simple Approach ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Chloride Diffusivity ◽  
Concrete Materials

The purpose of this study is to establish a simple approach to compute the chloride diffusivity of (non)carbonated concrete. The chloride diffusivity of concrete should is defined, based on engineering and scientific knowledge of cement and concrete materials. In this paper, parameters affecting the chloride diffusivity, such as the diffusivity in pore solution, tortuosity, micro-structural properties of hardened cement paste, volumetric portion of aggregate, are taken into consideration in the calculation of the chloride diffusivity of noncarbonated concrete. For carbonated concrete, reduced porosity due to carbonation is calculated and used for calculating the chloride diffusivity. The results are compared with experimental data and previous research works.

Einfluss der elektrochemischen Doppelschicht auf die Sorption und den Transport von Chlorionen im Zementstein / Influence of the electrochemical double layer on sorption and transport of chlorides in hardened cement paste

2000 ◽  
Vol 6 (4) ◽  
pp. 415-428
Author(s):  
O. Wowra ◽  
M.J. Setzer
Keyword(s):  
Double Layer ◽  
Cement Paste ◽  
Building Materials ◽  
Pore Solution ◽  
Chloride Ions ◽  
Transport Processes ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Electrochemical Double Layer

Abstract Besides the formation of Friedel salt the transport and binding of chlorides in concrete is mainly defined by the electrochemical double layer at the interface between cement matrix and pore solution. Due to the alkaline pore solution the surface of hardened cement paste is negatively charged which may change to positive values by the potential regulating calcium ions. Inverting of the surface charge leads to an attraction of anions and therefore, to an adsorption of chloride ions in the diffuse part of the electrochemical double layer. Influence from outside like sulphates and carbon dioxide may lead to a decomposition of Friedel salt. Apart from these effect temperature, pH-value and certain environmental conditions affects the electrochemical double layer as well. The chloride equilibrium is mainly controlled by adsorbed ions in the electrochemical double layer. The model presented here is relevant for the assessment of ion transport processes in mineral building materials. Continuing investigations may lead to optimize transport models and a better evaluation of the critical chloride threshold value in reinforced concrete.

scholarly journals Alkali Ion Concentration Estimations in Cement Paste Pore Solutions

2019 ◽  
Vol 9 (5) ◽  
pp. 992 ◽  
Author(s):  
Miguel Sanjuán ◽  
Esteban Estévez ◽  
Cristina Argiz
Keyword(s):  
Composite Materials ◽  
Cement Paste ◽  
Amorphous Silica ◽  
Reliable Method ◽  
Pore Solution ◽  
Ion Concentration ◽  
Alkali Silica Reaction ◽  
Distribution Method ◽  
Structural Problems ◽  
Over Time

The alkalinity of the pore solution is of great interest for evaluating the rising of the alkali–silica reaction (ASR) when reactive amorphous silica is found in some aggregates in some cement-based composites. This reaction is not desirable because it generates swelling gel materials around the aggregates, which produce an expansive pressure inside concrete over time, and can cause the cracking of concrete, leading to serious structural problems. The purpose of this study is to develop a quick, easy and reliable method to estimate the available alkali concentrations in the pore solution of cement-based composites. The bound alkalis were initially calculated based on Taylor’s alkali distribution method. The proposed procedure to estimate the available alkalis content is a reliable method for use in construction and building composite materials.

scholarly journals Thermal analysis of water confined in fully and partially saturated cement paste

2020 ◽  
Vol 172 ◽  
pp. 17008
Author(s):  
Dalia Bednarska ◽  
Marcin Koniorczyk
Keyword(s):  
Thermal Analysis ◽  
Cement Paste ◽  
Pore Solution ◽  
Cement Matrix ◽  
Complex Nature ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Scanning Calorimetry ◽  
Partially Saturated ◽  
Different Temperatures

The main object of the presented research is to apply thermal analysis in order to investigate microstructure of hardened cement paste. The test is conducted by means of differential scanning calorimetry on samples stored in various relative humidity levels as well as the fully saturated ones. The obtained results describe water solidification beginning at several different temperatures, which implies complex nature of cement paste microstructure. The recorded thermograms consist of two main peaks, which clearly indicate the division into capillary and gel pores. Additionally, the thermodynamic properties of actual pore solution confined in cement matrix are investigated. The obtained results indicate ions present in the liquid strongly affects its phase transition temperature as well as amount of ice formed during such the phase change.

The Thermal Deformation of Cement-Based Material at Low Temperatures

2014 ◽  
Vol 1081 ◽  
pp. 279-283 ◽  
Author(s):  
Nan Zhang ◽  
Juan Liao ◽  
Tao Zhang ◽  
Wen Zhan Ji
Keyword(s):  
Low Temperature ◽  
Cement Paste ◽  
Low Temperatures ◽  
Thermal Deformation ◽  
Pore Solution ◽  
Freezing Point ◽  
Bulk Solution ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Cement Based Materials

Thermal deformation of concrete at low temperature expands from-20°C to-50°C and contracts from-30°C to-10°C. Based on previous studies, the paper tries to explain the deformaion trend by analyzing freezing point of bulk solution and pore solution in saturated hardened cement paste. The result shows that it is critical to thermal deformation of cement-based materials at low temperature that pore solution in the pores smaller than 8 nm freezes.

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