Prediction of autogenous shrinkage in concrete from material composition or strength calibrated by a large database, as update to model B4

Rasoolinejad, Mohammad; Rahimi-Aghdam, Saeed; Bažant, Zdeněk P.

doi:10.1617/s11527-019-1331-3

Cited by 31 publications

(11 citation statements)

References 67 publications

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“…All mortar specimens with employed cements exhibited slight expansion during the water curing. These results correspond well with conclusions of Rasoolinejad et al [21], who thoroughly described the causes of the expansion during hydration, which were already mentioned in the introduction. The highest expansion exhibited CEM I 52.5, which attained approximately 0.6 mm/m after one year.…”

Section: Resultssupporting

confidence: 92%

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Shrinkage of Various Types of Portland Clinker-Based Cements With Respect to Their Hydration Degree

Davidová

Reiterman

2020

Acta Polytech

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The volume changes of cement based composites are significantly exhibited in the hardening process. Initial phases of the hardening are complemented by the expansion due to the heat evolution that is subsequently alternated by the shrinkage. Both could cause a crack initiation. It is evident that ultimate volume changes of cement based composites are a complex process, because the final shrinkage is determined by the binder used, exposition and also by the previous history. The paper focuses on the evaluation of the main types of cements based on the Portland clinker by using a conventional procedure for the determination of the shrinkage on the standard cements mortars. These mortars were exposed to drying after 1 and 3 days of curing, related to the actual degree of hydration, which was estimated on the basis of compressive strength development. The hydration process was additionally monitored using thermogravimetry on the accompanying paste specimens during one year. The performed experimental program confirmed the essential sense of the curing regime especially for blended cement systems, which exhibited very low values of the hydration degree at applied curing intervals. Despite the slightly higher values of shrinkage of blended cements, the obtained results signalize the crucial effect of prolonged curing for these types of binders. The conclusion highlighted the necessity of taking into consideration the hydration degree during cement testing by using the conventional contact method. Otherwise, the simple interpretation leads to an overestimation of the less-suitable material solution.

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Section: Resultssupporting

confidence: 92%

“…However, hardened cement paste evinces the porosity. Rasoolinejad et al [21] described that the process of hydration is expansive due to capillary pores in which the water is physically fixed. This hypothesis is valid for humid conditions, respectively in the presence of water, which is necessary for the hydration process.…”

Section: No /mentioning

confidence: 99%

Shrinkage of Various Types of Portland Clinker-Based Cements With Respect to Their Hydration Degree

Davidová

Reiterman

2020

Acta Polytech

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“…Expansion of 40-160 microstrain at nine months in those conditions may be considered usual values for normal concrete. Considering the total deformation in autogenous shrinkage tests is actually the sum of the "pure" autogenous shrinkage and the swelling [38], specimens underwater with w/c = 0.5 should present very low "pure" autogenous shrinkage, due to the large source of water, prevailing the swelling component. According to [38] hydration always causes expansion, and consequently, higher swelling may indicate higher hydration.…”

Section: Discussionmentioning

confidence: 99%

“…Considering the total deformation in autogenous shrinkage tests is actually the sum of the "pure" autogenous shrinkage and the swelling [38], specimens underwater with w/c = 0.5 should present very low "pure" autogenous shrinkage, due to the large source of water, prevailing the swelling component. According to [38] hydration always causes expansion, and consequently, higher swelling may indicate higher hydration. However, considering the expansion is caused by growing diameters of C-S-H shells surrounding the remnants of anhydrous cement grains, the swelling depends on contact pressure which is related with solid part configuration differing from paste to paste.…”

Section: Discussionmentioning

confidence: 99%

“…source of water, prevailing the swelling component. According to [38] hydration always causes expansion, and consequently, higher swelling may indicate higher hydration. However, considering the expansion is caused by growing diameters of C-S-H shells surrounding the remnants of anhydrous cement grains, the swelling depends on contact pressure which is related with solid part configuration differing from paste to paste.…”

Section: Discussionmentioning

confidence: 99%

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Influence of Steel Slag Type on Concrete Shrinkage

et al. 2020

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Building construction and building operations have a massive direct and indirect effect on the environment. Cement-based materials will remain essential to supply the growth of our built environment. Without preventive measures, this necessary demand in cement production will imply a substantial increase in CO2 generation. Reductions in global CO2 emissions due to cement consumption may be achieved by improvements on two main areas: increased use of low CO2 supplementary cementitious materials and a more efficient use of Portland cement clinker in mortars and concretes. The use of ground granulated blast furnace slag in concrete, as cement constituent or as latent hydraulic binder, is a current practice, but information of concrete with ladle furnace slag is more limited. Specific knowledge of the behavior of mixtures with steel slag in relation to certain properties needs to be improved. This paper presents the results of the shrinkage (total and autogenous) of five concrete mixtures, produced with different percentages of two different slags in substitution of cement. The results show that shrinkage of concrete with the two different slags diverges. These different characteristics of the two materials suggest that their use in combination can be useful in optimizing the performance of concrete.

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Vertical shortening prediction for super‐tall buildings considering enclosure effect and coupling effect

Zhao

Wang

2019

Structural Design Tall Build

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In this paper, the time-dependent vertical shortening behavior of the super-tall building is studied considering the enclosure effect and the coupling effect. A combined method to predict the overall strain of the mega section is firstly proposed by combining the B3 model and the fiber modeling approach to consider the enclosure effect of mega steel and validated by a series of in-house experiments. An iteration method is then proposed based on the construction sequence method to consider the coupling effect of stress and strain in the vertical shortening prediction and illustrated by a super-tall building project. Finally, the vertical shortening predictions of the super-tall building project are compared with the field monitoring records. The resultsshow that the strain predictions by the combined method show good agreement with experiments. Without considering the enclosure effect, the overall strain of mega section is overestimated. The coupling effect affects more on the vertical shortening of the mega column than on that of the shear wall and more on the elastic shortening than on the inelastic shortening. Without considering the coupling effect, the elastic shortening is significantly underestimated in the mega column but slightly overestimated in the shear wall. The predictions of vertical shortening in the shear wall show reasonable agreement with the measurements, whereas those in the mega column show large disagreement with the measurements, which enlightens the necessity to improve the prediction method further. KEYWORDS a combined method, an iteration method, coupling effect, enclosure effect, super-tall building, vertical shortening | INTRODUCTIONIn the past decades, the outrigger structural system has proven to be an efficient lateral stiffness system to reduce the lateral drift under the wind or seismic loading and widely adopted in super-tall buildings. However, this structural system suffers from the excessive stress to the structural members under the time-dependent actions, such as the shrinkage and creep. Vertical shortening is one of the major considerations in the design and construction of super-tall buildings. The differential vertical shortening could cause adverse effects on the nonstructural elements of buildings, such as the curtain walls, partitions, electrical pipelines, and elevators and may also result in redistribution of structural member forces.The vertical shortening prediction of super composite components mainly contains two aspects. The one is the model utilized to predict shrinkage and creep, which is kind of material-level issue, whereas the other one is related to the structure-level issue, that is, how to deal with the composite structural components. Shrinkage and creep are the natural characteristics of concrete along with the formation, the development, and

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Prediction of autogenous shrinkage in concrete from material composition or strength calibrated by a large database, as update to model B4

Cited by 31 publications

References 67 publications

Shrinkage of Various Types of Portland Clinker-Based Cements With Respect to Their Hydration Degree

Shrinkage of Various Types of Portland Clinker-Based Cements With Respect to Their Hydration Degree

Influence of Steel Slag Type on Concrete Shrinkage

Vertical shortening prediction for super‐tall buildings considering enclosure effect and coupling effect

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