Autogenous relative humidity change in silica fume-modified cement paste

Jensen, Ole Mejlhede; Hansen, Poul Henrik Kyvsgaard

doi:10.1680/adcr.1995.7.25.33

Cited by 83 publications

(86 citation statements)

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“…For replicate specimens, the maximum standard deviation in RH was 0.42 %, with an average standard deviation of 0.17 % (Bentz et al 2001a). (Jensen and Hansen 1996) for cement mortars (w/cm=0.35) with and without SRA A, cured under sealed conditions at 30 o C (Bentz et al 2001a). For replicate specimens, the maximum standard deviation in deformation was 27 microstrains, with typical standard deviations being in the range of 5 microstrains to 17 microstrains (Bentz et al 2001a).…”

Section: Resultsmentioning

confidence: 97%

“…Different cement pastes and mortar specimens were prepared and evaluated as detailed in Table 1. The following measurements were performed on the pastes and mortars: X-ray transmission (absorption) (Bentz et al 2001a, Bentz andHansen 2000), bulk mass loss, internal RH Hansen 1995a, Jensen andHansen, 1996), autogenous deformation Hansen 1995b, Jensen andHansen 1996), and low temperature calorimetry (LTC) (Bentz and Stutzman 2006). In addition, the viscosity of distilled water and 10 % solutions (by mass) of two different SRAs were measured using a Cannon-Fenske Routine Viscometer.…”

Section: Methodsmentioning

confidence: 99%

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Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes

Bentz

2006

ACT

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Because most shrinkage-reducing admixtures (SRAs) significantly reduce the surface tension of a cement paste pore solution, they will naturally influence all physical properties and processes that are dependent in some way on surface tension. Such properties include internal relative humidity, capillary stresses, and freezing point depression, all via the Kelvin equation and its variants (Kelvin-Laplace, Gibbs-Thomson). Processes that will thus be strongly influenced by the presence of SRAs include drying, autogenous stress and strain development, and freezing. In this paper, experimental measurements of these processes in cement pastes and mortars with and without SRA additions will be presented in light of the Kelvin equation. The experimental measurements that are applied to early-age specimens include X-ray absorption measurements to quantify drying profiles, bulk mass loss measurements, measurements of internal relative humidity, assessments of autogenous deformation under sealed curing conditions, and low temperature calorimetry scans to quantify freezable water content. The results indicate that SRAs can provide benefits in several new applications beyond their conventional usage to reduce drying shrinkage.

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Section: Resultsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes

Bentz

2006

ACT

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“…The dilatometric technique has been tested during years of research work on binder phases of HPC (Jensen and Hansen 2002;Jensen and Hansen 1995;Jensen and Hansen 1993;Jensen and Hansen 1999). A particular characteristic of this measuring technique is the encapsulation of the hardening cement-based material in a specially designed, corrugated polyethylene mould; this effectively prevents moisture loss and ensures insignificant restraint during the hardening of the specimen.…”

Section: Experimental Programmentioning

confidence: 99%

“…1/2) and the paste volume 49 %, for the slump requirements of the dilatometric technique (Jensen and Hansen 2002, 1995, 1993, 1999. The volumetric proportions of the mortars constituents for the eight tested mixtures are provided in Table 3.…”

Section: Experimental Programmentioning

confidence: 99%

“…2, 3 and 4. Each deformation course has been adjusted to zero at the moment of setting (Philleo 1999;Jensen and Hansen 2002, 1993Assmann 2013Mechtcherine and Reinhardt 2012), which occurred approximately at 5 h after water addition. Figure 2 shows the measured autogenous deformation for CEC and Pumice with the amount of entrained water calculated from chemical shrinkage as fully saturated.…”

Section: Autogenous Deformationmentioning

confidence: 99%

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Effects of Fine LWA and SAP as Internal Water Curing Agents

Sensale

Gonçalves

2014

Int J Concr Struct Mater

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Typical high-performance concrete (HPC) mixtures are characterized by low water-cementitious material ratios, high cement contents, and the incorporation of admixtures. In spite of its superior properties in the hardened state, HPC suffers from many practical difficulties such as its sensitivity to early-age cracking (which is associated with self-desiccation and autogenous shrinkage). In this context, conventional curing procedures are not sufficiently effective to address these limitations. In order to overcome this issue, two strategies, which are based on the use of internal reservoirs of water, have been recently developed. One of these strategies is based on the use of lightweight aggregates (LWA), while the other is based on the use of superabsorbent polymers (SAP). This paper studies and compares the efficiency of the LWA and SAP approaches. Moreover, some of the theoretical aspects that should be taken into account to optimize their application for internal curing of HPC are also discussed. Two fine LWA's and one SAP are studied in terms of autogenous deformation and compressive strength. Increasing the amounts of LWA or SAP can lead to a reduction of the autogenous deformation and compressive strength (especially when adding large amounts). By selecting appropriate materials and controlling their amount, size, and porosity, highly efficient internal water curing can be ensured.

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Frühe autogene Verformungen von HPC: Beurteilung des plastischen Schwindens und spannungsinduzierender Verformungen durch Korrelation mit der Hydratationskinetik

Fontana

2005

Beton- und Stahlbetonbau

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Autogenous relative humidity change in silica fume-modified cement paste

Cited by 83 publications

References 0 publications

Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes

Influence of Shrinkage-Reducing Admixtures on Early-Age Properties of Cement Pastes

Effects of Fine LWA and SAP as Internal Water Curing Agents

Frühe autogene Verformungen von HPC: Beurteilung des plastischen Schwindens und spannungsinduzierender Verformungen durch Korrelation mit der Hydratationskinetik

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