Depth-related variation in conductivity to study cover-zone concrete during wetting and drying

Chrisp, T. M.; McCarter, William John; Starrs, G.; Basheer, Pam; Blewett, J.

doi:10.1016/s0958-9465(01)00073-7

Cited by 41 publications

(25 citation statements)

References 18 publications

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“…Both systems allow discretised electrical measurements to be taken within the concrete cover-zone, although the electrode geometry and layout is significantly different in both systems. The current work focuses on the covercrete electrode array used and detailed in previous laboratorybased studies [1,2]. In summary, the sensor comprises 10 electrode pairs mounted on a small plexiglas former.…”

Section: Covercrete Sensorsmentioning

confidence: 99%

Field monitoring of electrical conductivity of cover-zone concrete

McCarter

Chrisp

Starrs

et al. 2005

Cement and Concrete Composites

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A sensor system, developed in a previous laboratory study [ , is used to obtain the spatial distribution of electrical conductivity within the cover-zone of concrete specimens subjected to a range of natural exposure conditions. The testing methodology enables in-situ monitoring of the electrical conductivity and technical issues relating to site measurements are discussed. The work also highlights the need for continual monitoring of the covercrete as the electrical conductivity changes with time, depth and environment.

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Section: Covercrete Sensorsmentioning

confidence: 99%

Field monitoring of electrical conductivity of cover-zone concrete

McCarter

Chrisp

Starrs

et al. 2005

Cement and Concrete Composites

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“…Results obtained by Abdul Razak et al (2004), Chan and Ji (1999) and McCarter and Watson (1997) using a variety of test methods including electrical conduction measurements, ISAT and the water absorption test detailed in BS 1881-122 (BSI, 2011 all found that the use of silica fume (SF) additions reduces the sorptivity of concrete when compared with plain OPC concrete. However, the results of tests on mixes containing pulverised fly ash (pfa) and ground granulated blastfurnace slag (GGBS) are sometimes contradictory when compared with each other or plain OPC concrete, perhaps because of differences in Unfortunately, the results of these experiments cannot be used to model chloride ingress in any meaningful way and hence estimate the depth of concrete cover needed to prevent corrosion in structures exposed to cyclic wet-dry chloride environments because (a) the absorbing solution used is normally water, which behaves somewhat differently to salt solution because of factors such as pore blocking due to chloride binding and/or crystallisation of chloride salts (Chrisp et al, 2002), and differences in the densities of the two liquids (Emerson and Butler, 1997) (b) in many cases the moisture content of test specimens is unlikely to be representative of field conditions and this can significantly affect sorptivity (Arya et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Chloride penetration in concrete subject to wet–dry cycling: influence of pore structure

Arya

Vassie

Bioubakhsh

2014

Proceedings of the Institution of Civil Engineers - Structures

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The objective of the work is to investigate the effect on the distribution of chloride at different depths of some factors concerning concrete pore structure, namely water/cementitious material ratio, cement type and percentage ground granulated blast furnace slag (GGBS). Concrete cubes are subjected to repeated wetting and drying cycles with various concentrations of sodium chloride solution, during which their mass is monitored. The effective porosity, weight and distance sorptivity and chloride solution penetration depths are calculated. Samples are extracted from the cubes at a range of depths and analysed for chloride content. The results show that the most significant effect of sorptivity on long-term chloride ingress to concrete is its effect on surface chloride content.The value of this parameter is a way of taking account of absorption when modelling chloride ingress under cyclic wetting and drying conditions. The values of cover depth recommended in BS8500-1 that are needed to ensure a time to corrosion of 100 year are calculated assuming the surface chloride content is 0 . 14% for GGBS and pulverised fuel ash (PFA) concretes. Our cyclic wetting and drying experiments produce higher surface chloride contents (0 . 29-0 . 62%) that would lower the time to corrosion using the cover depths recommended in the code.

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“…To facilitate electrical measurements within the cover-zone, the Authors have modified a multi-electrode array (McCarter et al, 1995;Chrisp et al, 2002) which is embedded within concrete specimens at the time of casting. The array allows monitoring of the spatial distribution of both electrical resistance and temperature within the cover region.…”

Section: Embedded Electrode Arraymentioning

confidence: 99%