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.

Electrical Resistivity and Dielectric Properties of Hardened Cement Paste and Mortar

1995 ◽  
Vol 411 ◽  
Author(s):  
D. Buerchler ◽  
B. Elsener ◽  
H. Boehni
Keyword(s):  
Electrical Resistivity ◽  
Dielectric Properties ◽  
Water Content ◽  
Cement Paste ◽  
Pore Solution ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Solution Composition ◽  
Cement Based Materials

ABSTRACTWater content, porosity, pore solution composition, resistivity and dielectric properties of hardened cement paste and mortar samples have been studied as a function of time and relative humidities. A model for the resistivity of cement based materials is presented and an interpretation of the dielectric properties is proposed.

scholarly journals Effect of Ground Slag on Mechanical Properties of Concrete under Low Temperature

2021 ◽  
Vol 2109 (1) ◽  
pp. 012019
Author(s):  
Xuelian Yuan ◽  
Jie Hu
Keyword(s):  
Mechanical Properties ◽  
Fracture Toughness ◽  
Compressive Strength ◽  
Low Temperature ◽  
Cement Paste ◽  
High Volume ◽  
Hardened Cement ◽  
Micro Structure ◽  
Hardened Cement Paste ◽  
Fracture Properties

Abstract Through using cube resisting compression test, fracture properties and micro-structure, the mechanical properties of high volume ground slag concrete under low temperature are studied in this paper. The results show that low temperature can improve the compressive strength of high volume ground slag concrete. And strength increased with the decreased of temperature. Low temperature can also improve the fracture energy and fracture toughness. Not only can ground slag reduce the content of calcium hydroxide in hardened cement paste, but ground slag can improve the compactness of hardened cement paste, reduce porosity and improve the strength of the interface.

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 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.

Macro-Defect-Free Cement: A Review

1989 ◽  
Vol 179 ◽  
Author(s):  
J. Francis Young
Keyword(s):  
Cement Paste ◽  
Casting Process ◽  
Particle Dispersion ◽  
Particle Packing ◽  
Hardened Cement ◽  
High Porosity ◽  
Hardened Cement Paste ◽  
Water Requirements ◽  
Wide Range ◽  
Cement Based Materials

Cement-based materials have been traditionally formed by casting. The amount of water used in the casting process determines the porosity of the hardened material. The water requirements, and the tendency for cement grains to agglomerate, result in hardened cement paste having high porosity and a wide range of pore sizes. Consequently, such materials are not very strong and contain critical flaws whose dimensions are of the order of 0.1 mm. Although improvements in particle packing and particle dispersion to reduce porosity have resulted in significant increases in strength, such materials are still very brittle and have relatively low tensile and flexural strengths.

Sign in / Sign up

Export Citation Format

Share Document