Electrical Resistivity and Dielectric Properties of Hardened Cement Paste and Mortar

Buerchler, D.; Elsener, Bernhard; Boehni, H.

doi:10.1557/proc-411-407

Cited by 31 publications

(17 citation statements)

References 9 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…There are many studies about the relationship between the ionic concentration in pore solution and these fore-mentioned criteria in cement-based materials, especially chloride ions. The concentration of chloride ions in pore solution is also studied widely while cement based materials are added or contaminated with different quantity of chloride ions (Bertolini et al 2004;Burchler et al 1996;Larbi et al 1990;Tritthart 1989aTritthart , 1989bTritthart , 1992Tritthart , 2009Tritthart et al 2003). Nowadays, the relationship between free chloride and bound chloride can generally be represented by the Fleundlich isotherm equation at high free chloride concentrations and the Langmuir isotherm equation at low free chloride concentration (Tang et al 1993;Delagrave et al 1997); and the effects of other criteria are described by adsorption constants which varied widely.…”

Section: B)mentioning

confidence: 99%

Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

Nguyen

Yokota

Hashimoto

2015

ACT

View full text Add to dashboard Cite

The adverse effects of the long term application of electrochemical chloride extraction on binding capacity of hydrated cement products are innegligible. In this study, the influences of electrochemical chloride extraction in the microstructural properties of hydrated cement products of cement pastes were investigated in paste specimens by using a modified migration cell that was conducted with the applied current density of 4.5 A/m 2 and synthesized pore solutions as electrolytes for 8 weeks. Three types of cement pastes were used with the water-to-binder ratio of 0.4 including ordinary Portland cement (OPC), fly ash cement (FC) and ground granulated blast furnace slag cement (SC) pastes. Chloride source was supplied by adding 1.5% sodium chloride. After extraction, the acid-soluble and water-soluble chloride contents significantly reduced. Portlandite content increased proportionally with the time of extraction in OPC and FC pastes although the contribution of calcium ions in transferring the current is negligible. Some unsteady gel phases was obtained after a short time the extraction was stopped. Furthermore, the alteration and decomposition of C-S-H were inevitable with different rates depending on the type of cement.

show abstract

Section: B)mentioning

confidence: 99%

Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

Nguyen

Yokota

Hashimoto

2015

ACT

View full text Add to dashboard Cite

show abstract

“…Unfortunately, the on-site measurement of corrosion rate of embedded metals is rather difficult. Other types of measurements, such as the corrosion potential of the metal and the electrical resistivity of the mortar can be carried out easily, even with embedded probes that allow continuous monitoring, similar to those normally used to monitor corrosion of steel reinforcement in concrete structures [29,30]. The results summarised in Table 2 show that the measurement of the corrosion potential is a useful non-destructive means to assess corrosion behaviour of steel even in mortars of different composition.…”

Section: Bindermentioning

confidence: 99%

Corrosion behaviour of metal inserts in simulated ancient masonry mortars

Carsana

Marra

Bertolini

2015

Construction and Building Materials

View full text Add to dashboard Cite

h i g h l i g h t sCorrosion of metal inserts in aerial and hydraulic mortars was studied. Carbon steel, stainless steel and titanium inserts were considered. Mortar composition had a secondary effect on the corrosion rate compared to the role of moisture. High corrosion rate was measured only for carbon steel in mortars exposed to 95% RH or water suction. Mortar resistivity was found to be a reliable parameter to assess corrosion of embedded inserts. a r t i c l e i n f o b s t r a c tCorrosion of metal inserts may be detrimental to the durability of masonry. The paper discusses corrosion of carbon steel, stainless steel and titanium embedded in aerial and hydraulic mortars simulating those of ancient walls. The effects of temperature (5-40°C), moisture (65-95% RH and water suction) and electrical resistivity of mortars on the corrosion of metal inserts are discussed. Results showed that the corrosion rate of embedded steel, regardless of the mortar composition, is negligible in mortars exposed to 65-80% RH (even at 40°C) and modest even at 95% RH, while high values were obtained in the presence of water uptake.

show abstract

“…Based on the assumption of a fractal structure of cement paste (two phase system, conducting phase = pores, isolating phase = matrix) the resisitivity ρ of cement based materials can be calculated by [12] 1/ρ = σ = σ 0 (p 0 -p c ) γ (1) σ conductivity σ0 conductivity of pore solution p0 volume fraction of pore solution pc percolation threshold γ percolation exponent The resistivity of cement paste and mortars with different w/c ratios stored at RH 60 -100% until rreaching the equilibirum humidity could be described and predicted very accurately based on the percolation theory and eq. (1).…”

Section: Resistivity Of Cement Pastementioning

confidence: 99%

A Percolation Model for Water Sorption in Porous Cementitious Materials

Elsener

Flückiger

Böhni

2000

Materials for Buildings and Structures

View full text Add to dashboard Cite

The highly disordered pore system of cement paste is described and numerically modelled as fractal structure. Water sorption experiments on cement paste with different porosity and numerical percolation experiments with Monte Carlo simulations are performed and have shown to be self similar, thus the percolation theory with the percolation threshold pc describes the kinetics of water sorption at all porosities consistently. With the same percolation model (connectivity of pores) the deviation from the classical power law for water sorption at long times and low porosities, the drastic reduction of the effective diffusion coefficient and the sharp increase in resisitivity with lower porosity and lower relative humidity can be explained. IntroductionThis microstructure of cement paste consists of solid and porous phases, and it is the spatial and topological arrangement of these phases that is ultimately responsible for the strength and transport properties of the paste. One key topological attribute is the connectivity or percolation of phases within this microstructure (figure 1): a percolating phase forms a three dimensional spanning cluster, while a phase that has not percolated consists of isolated clusters [1]. The durability or service life of cement-based materials is also directly influenced by phase percolation because the transport properties of such materials are determined to a large degree by the amount and connectivity of the capillary porosity within the microstructure. For water sorption in cement paste and for diffusion of degradative species, such as chloride ions, both the connectivity of the pore space and of the porous hydration products are critical: as the capillary porosity becomes disconnected at low w/c ratios or long hydration times, transport rates decrease markedly and become controlled by the gel porosity of the highly-connected calcium silicate hydrate phase [2]. The kinetics of water sorption of porous cement based materials as cement paste, mortar or concrete are generally described by the classical theory with the capillary or potential model resulting in the well known square root dependance of water uptake with time [3]. A lot of literature results, however, showed that this square root law does not fit the experimental data [4] at longer times and / or at low porosity. To explain these deviations, a new model based on the percolation theory has been proposed [5]. The structure of cement paste is described with a 3-d simple cubic lattice, the sites of the lattice being occupied with a probability p

show abstract

Electrical Resistivity and Dielectric Properties of Hardened Cement Paste and Mortar

Cited by 31 publications

References 9 publications

Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

Effects of Electrochemical Chloride Extraction on Hydrated Products of Various Cement Paste Systems

Corrosion behaviour of metal inserts in simulated ancient masonry mortars

A Percolation Model for Water Sorption in Porous Cementitious Materials

Contact Info

Product

Resources

About