Effect of Chemical Admixtures on Apparent Activation Energy of Cementitious Systems

Poole, Jonathan L.; Riding, Kyle A.; Juenger, Maria; Folliard, Kevin J.; Schindler, A.

doi:10.1061/(asce)mt.1943-5533.0000345

Cited by 23 publications

(9 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…8,9 Chemical admixtures, especially set control admixtures, can significantly affect the heat of hydration rate and the concrete element temperature development. 10 The water-cementitious materials ratio (w/cm) is also known to affect the total heat released per gram of cementitious material from hydration, as a higher w/cm will provide more water and available space for more of the cement to ultimately react. [11][12][13][14][15] This study documents the development of a model for calculating the concrete heat of hydration based on a large data set of 204 concrete mixtures tested using semi-adiabatic calorimetry, evaluating the impacts of several compositional…”

Section: Background: Existing Methods For Heatmentioning

confidence: 99%

“…. ) p slag (10) Equations 8 through 10 were validated using the results of eight semi-adiabatic calorimetry tests conducted at pavement fi eld sites and published degree of hydration results. 14,28 The w/cm in Eq.…”

Section: Background: Existing Methods For Heatmentioning

confidence: 99%

“…(8) through (10). The model was based on a data set consisting of the results from 23 semi-adiabatic calorimetry tests and the same Lerch and Ford 17 data set used by Schindler and Folliard.…”

Section: Background: Existing Methods For Heatmentioning

confidence: 99%

See 2 more Smart Citations

Modeling Hydration of Cementitious Systems

Riding

Poole²,

Folliard³

et al. 2012

View full text Add to dashboard Cite

heat loss is measured and minimized by the use of insulation. The concrete adiabatic temperature rise is then back-calculated with the increased heat of hydration rate from the higher temperatures in adiabatic conditions taken into account. Semiadiabatic calorimetry is much easier to perform than adiabatic calorimetry, and it can even be performed in the fi eld. Higher temperature speeds the rate of the cementitious material hydration reactions. The infl uence of temperature on the hydration rate can be accounted for by the use of a maturity function. The equivalent age maturity function is commonly used with strength or degree of hydration calculations, as shown in Eq. (1 where t e (hours) is the equivalent age or time that the concrete would take to achieve the same property while being cured at an isothermal temperature at the reference temperature T r (K); E a is the apparent activation energy (J/mol); R is the universal gas constant (8.314 J/mol/K [10.732 ft 3 psia/°R/ lb-mol]); T C is the temperature of the concrete (K); and ∆t is the time step used. In practical terms, the equivalent age of a concrete mixture is the amount of time that the concrete mixture would need to be cured at an isothermal reference temperature to reach the same property as the concrete under the different time-temperature history. The equivalent age maturity method has been shown to well account for the effects of different placement temperature 3 and curing conditions 1 on the concrete heat of hydration development. The apparent activation energy term is a measure of the temperature sensitivity of the hydration reaction.2,4,5 A mechanistic-empirical model was developed for predicting E a by Poole 6 from isothermal calorimetry experiments, as shown in Eq. (2) INTRODUCTION Concrete temperature development during hydration is a major factor in determining the long-term strength, permeability, durability, and cracking probability. The mixture proportions, curing, and construction schedule can be optimized to control concrete temperature and improve concrete performance. To determine optimum mixture proportions and placement conditions, heat transfer software can be used to model the combined effects of the weather, member geometry, insulation, boundary conditions, and concrete heat of hydration to predict internal concrete temperatures. Such software requires the rate and amount of concrete heat generation as input parameters. Measuring the rate and amount of heat released during hydration to provide input for a model can take a week or longer per mixture in a specialized calorimeter and can be costly. Therefore, a comparison of several candidate mixtures using laboratory test results could require several weeks. A predictive model for the concrete heat released during hydration, based on the constituent materials and mixture proportions, would reduce the need for this costly testing. This study documents the test methods, materials, and statistical methods used to develop and validate a model for predicting the concrete heat release...

show abstract

Section: Background: Existing Methods For Heatmentioning

confidence: 99%

Section: Background: Existing Methods For Heatmentioning

confidence: 99%

See 1 more Smart Citation

Modeling Hydration of Cementitious Systems

Riding

Poole²,

Folliard³

et al. 2012

View full text Add to dashboard Cite

show abstract

“…e adiabatic temperature rise formulas used in the calculation are equations ( 14) and (15). e calculation results are shown in Figures 22 and 23.…”

Section: Numerical Simulation Resultsmentioning

confidence: 99%

“…As an effective means to improve the thermal and mechanical properties of concrete, concrete admixtures have been widely used in engineering [13][14][15]. Commonly used concrete admixtures include water-reducing agents, retarders, air-entraining agents, etc., among which water-reducing agents can reduce the use of water and reduce the heat released by the hydration reaction [16].…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydration Heat Inhibitor on Thermal Stress of Hydraulic Structures with Different Thicknesses

Shen

et al. 2020

Advances in Civil Engineering

View full text Add to dashboard Cite

Concrete hydration heat inhibitor can inhibit the early hydration reaction of concrete and reduce the initial heat release of concrete. However, there is no in-depth research on the effect of hydration heat inhibitor on hydraulic structures with different thicknesses and constraints. In this paper, numerical simulation is used to study the change of temperature and stress field after adding hydration heat inhibitor by establishing the finite element models of tunnel lining, sluice, and gravity dam. The results show that the effect of the hydration heat inhibitors on reducing the temperature peak is inversely proportional to the thickness of the structure. A formula is put forward to evaluate their relation in this paper. When the thickness of the structure is about 6 m, there is no peak cutting effect. For the stress field, hydration heat inhibitor can greatly reduce the thermal stress of the thin-walled structure and make the structure meet the temperature control requirements; for the medium wall thickness structure, it can reduce the internal tensile stress about 50% and the surface tensile stress about 20%, and other temperature control measures are still needed to ensure that the surface tensile stress of the structure meets the requirements; for hydraulic structures with large volume and thickness, the application effect of the inhibitor has limitations, which can reduce the internal tensile stress about 30%, but the tensile stress in the surface area will increase about 7% due to the increase of the internal and external temperature difference; therefore, other temperature control measures such as arranging cooling water pipe, strengthening surface insulation, and so on are needed to ensure that temperature cracks do not occur. This paper provides references and suggestions for the research and engineering application of hydration heat inhibitor.

show abstract