Estimation of compressive strength by a new apparent activation energy function

Ground granulated blast furnace slag (GGBFS) conventionally has been incorporated with ordinary Portland cement (OPC) owing to reduce the environmental load and enhance the engineering performance. Concrete with GGBFS shows different strength development of normal concrete, but sensitive, to exterior condition. Thus, a precise strength evaluation technique based on a quantitative model like full maturity model is required. Many studies have been performed on strength development of the concrete using equivalent age which is based on the apparent activation energy. In this process, it considers the effect of time and temperature simultaneously. However, the previous models on the apparent activation energy of concrete with mineral admixtures have limitation, and they have not considered the effect of temperature on strength development. In this paper, the apparent activation energy with GGBFS replacement ratio was calculated through several experiments and used to predict the compressive strength of GGBFS concrete. Concrete and mortar specimens with 0.6 water/binder ratio, and 0 to 60% GGBFS replacement were prepared. The apparent activation energy (Ea) was experimentally derived considering three different curing temperatures. Thermodynamic reactivity of GGBFS mixed concrete at different curing temperature was applied to evaluate the compressive strength model, and the experimental results were in good agreement with the model. The results show that when GGBFS replacement ratio was increased, there was a delay in compressive strength.

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Apparent Activation Energy for Predicting Compressive Strength of Concrete Using Blast Furnace Slag

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.764-765.13 ◽

2015 ◽

Vol 764-765 ◽

pp. 13-17

Author(s):

Hyun Min Yang ◽

Myung Won Cho ◽

Won Jun Park ◽

Han Seung Lee

Keyword(s):

Activation Energy ◽

Compressive Strength ◽

Blast Furnace ◽

Apparent Activation Energy ◽

Blast Furnace Slag ◽

Strength Development ◽

Maturity Model ◽

Age Model ◽

Compressive Strength Of Concrete ◽

Furnace Slag

Concrete with blast furnace slag (BFS) shows varied strength development properties under general temperature conditions. Therefore, a precise prediction of compressive strength using a full maturity model is desired. The purpose of this study is to predict the compressive strength of concrete with BFS by calculating the apparent activation energy (Ea) for each BFS replacement ratio, applying this activation energy to the equivalent age model, and then using the Carino model. For BFS replacement ratios of 0%, 10%, 30%, and 50%, Eais calculated as 33.475 kJ/mol, 37.325 kJ/mol, 41.958 kJ/mol and 45.541 kJ/mol respectively. Finally, the compressive strength of concrete with BFS is predicted.

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Isothermal Calorimetry and Compressive Strength Tests of Mortar Specimens for Determination of Apparent Activation Energy

Journal of Materials in Civil Engineering ◽

10.1061/(asce)mt.1943-5533.0003634 ◽

2021 ◽

Vol 33 (4) ◽

pp. 04021035

Author(s):

Aleksandra Kuryłowicz-Cudowska ◽

Elzbieta Haustein

Keyword(s):

Activation Energy ◽

Compressive Strength ◽

Apparent Activation Energy ◽

Isothermal Calorimetry ◽

Strength Tests

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The Apparent Activation Energy of a Novel Low-Calcium Silicate Hydraulic Binder

Materials ◽

10.3390/ma14185347 ◽

2021 ◽

Vol 14 (18) ◽

pp. 5347

Author(s):

Mónica Antunes ◽

Rodrigo Lino Santos ◽

João Pereira ◽

Ricardo Bayão Horta ◽

Patrizia Paradiso ◽

...

Keyword(s):

Activation Energy ◽

Compressive Strength ◽

Apparent Activation Energy ◽

Isothermal Calorimetry ◽

Hydration Product ◽

Specific Rate ◽

Initial Development ◽

Low Calcium ◽

Acceleration Period ◽

Different Temperatures

In this work, the apparent activation energy (Ea) of a novel low-calcium binder was, for the first time, experimentally determined, using a calorimetric approach. Additionally, a correlation between the Ea, measured at the acceleration period with the C/S ratio of the hydration product is proposed. The Ea of the prepared pastes was determined through isothermal calorimetry tests by calculating the specific rate of reaction at different temperatures, using two different approaches. When comparing the Ea, at the acceleration period of this novel binder with the one published for alite and belite, we observed that its value is higher, which may be a result of a different hydration product formed with a distinct C/S ratio. Finally, to study the temperature effect on the compressive strength at early ages, a set of experiments with mortars was performed. The results showed that the longer the curing time at 35 °C, the higher the compressive strength after 2 days of hydration, which suggests a higher initial development of hydration products. This study also indicated that the novel binder has a higher sensitivity to temperature when compared with ordinary Portland cement (OPC).

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The Hydrothermal Stability and the Properties of Non- and Strongly-Interacting Rh Species over Rh/γ, θ-Al2O3 Catalysts

Catalysts ◽

10.3390/catal11010099 ◽

2021 ◽

Vol 11 (1) ◽

pp. 99

Author(s):

Guanghao Cheng ◽

Gurong Shen ◽

Jun Wang ◽

Yunhao Wang ◽

Weibo Zhang ◽

...

Keyword(s):

Activation Energy ◽

Apparent Activation Energy ◽

Aging Time ◽

Reaction Path ◽

Aging Treatment ◽

Hydrothermal Stability ◽

Hydrothermal Aging ◽

Strongly Interacting

The present work reports the effects of γ-, θ-phase of alumina on the hydrothermal stability and the properties of non- and strongly-interacting Rh species of the Rh/Al2O3 catalysts. Comparing to γ-Al2O3, θ-Al2O3 can not only reduce the amount of occluded Rh but also better stabilize Rh during hydrothermal aging treatment. When the aging time was prolonged to 70 h, all the non-interacting Rh was transformed into strongly-interacting Rh and occluded Rh. The XPS results indicated that non- and strongly-interacting Rh might exist in the form of Rh/Rh3+ and Rh4+, respectively. CO-NO reaction was chosen as a probe reaction to research more information about non- and strongly-interacting Rh. The two Rh species had similar apparent activation energy (Eapp) of 170 kJ/mol, which indicated that non- and strongly-interacting Rh follow the same reaction path. The non-interacting Rh was removed from aged samples by the acid-treated method, and obtained results showed that only 2.5% and 4.0% non-interacting Rh was maintained in aged Rh/γ-Al2O3 and Rh/θ-Al2O3.

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The activation energy U(T,B) in high temperature superconductor

The European Physical Journal Applied Physics ◽

10.1051/epjap/2020200223 ◽

2020 ◽

Vol 92 (2) ◽

pp. 20601

Author(s):

Abdelaziz Labrag ◽

Mustapha Bghour ◽

Ahmed Abou El Hassan ◽

Habiba El Hamidi ◽

Ahmed Taoufik ◽

...

Keyword(s):

Magnetic Field ◽

Activation Energy ◽

Phase Diagram ◽

High Temperature ◽

Apparent Activation Energy ◽

High Temperature Superconductor ◽

Flux Flow ◽

Resistivity Measurements ◽

Vortex Phase ◽

The Magnetic Field

It is reported in this paper on the thermally assisted flux flow in epitaxial YBa2Cu3O7-δ deposited by Laser ablation method on the SrTiO3 substrate. The resistivity measurements ρ (T, B) of the sample under various values of the magnetic field up to 14T in directions B∥ab-plane and B∥c-axis with a dc weak transport current density were investigated in order to determine the activation energy and then understand the vortex dynamic phenomena and therefore deduce the vortex phase diagram of this material. The apparent activation energy U0 (B) calculated using an Arrhenius relation. The measured results of the resistivity were then adjusted to the modified thermally assisted flux flow model in order to account for the temperature-field dependence of the activation energy U (T, B). The obtained values from the thermally assisted activation energy, exhibit a behavior similar to the one showed with the Arrhenius model, albeit larger than the apparent activation energy with ∼1.5 order on magnitude for both cases of the magnetic field directions. The vortex glass model was also used to obtain the vortex-glass transition temperature from the linear fitting of [d ln ρ/dT ] −1 plots. In the course of this work thanks to the resistivity measurements the upper critical magnetic field Hc2 (T), the irreversibility line Hirr (T) and the crossover field HCrossOver (T) were located. These three parameters allowed us to establish a phase diagram of the studied material where limits of each vortex phase are sketched in order to optimize its applicability as a practical high temperature superconductor used for diverse purposes.

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Effect of CaO on catalytic combustion of semi-coke

Green Processing and Synthesis ◽

10.1515/gps-2021-0002 ◽

2021 ◽

Vol 10 (1) ◽

pp. 011-020

Author(s):

Luyao Kou ◽

Junjing Tang ◽

Tu Hu ◽

Baocheng Zhou ◽

Li Yang

Keyword(s):

Activation Energy ◽

Apparent Activation Energy ◽

Combustion Rate ◽

Activation Energies ◽

Combustion Reaction ◽

Tg Analysis ◽

Conversion Rates ◽

Apparent Activation Energies ◽

Ozawa Integral Method ◽

Addition Amount

Abstract Generally, adding a certain amount of an additive to pulverized coal can promote its combustion performance. In this paper, the effect of CaO on the combustion characteristics and kinetic behavior of semi-coke was studied by thermogravimetric (TG) analysis. The results show that adding proper amount of CaO can reduce the ignition temperature of semi-coke and increase the combustion rate of semi-coke; with the increase in CaO content, the combustion rate of semi-coke increases first and then decreases, and the results of TG analysis showed that optimal addition amount of CaO is 2 wt%. The apparent activation energy of CaO with different addition amounts of CaO was calculated by Coats–Redfern integration method. The apparent activation energy of semi-coke in the combustion reaction increases first and then decreases with the increase in CaO addition. The apparent activation energies of different samples at different conversion rates were calculated by Flynn–Wall–Ozawa integral method. It was found that the apparent activation energies of semi-coke during combustion reaction decreased with the increase in conversion.

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