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

Materials ◽  
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).

scholarly journals Instantaneous activation energy of alkali activated materials

2019 ◽  
Vol 3 ◽  
pp. 121-123
Author(s):  
Shiju Joseph ◽  
Siva Uppalapati ◽  
Ozlem Cizer
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Reaction Rate ◽  
Arrhenius Equation ◽  
Isothermal Calorimetry ◽  
Traditional Methods ◽  
Cement Based Materials ◽  
Different Temperatures ◽  
Higher Temperature ◽  
Alkali Activated

Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.

Nitridation Isothermal Kinetics of In Situ β-Sialon Bonded Al2O3-C Refractories

2016 ◽  
Vol 697 ◽  
pp. 572-575
Author(s):  
Xue Qing Yang ◽  
Nai Peng ◽  
Cheng Ji Deng
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Isothermal Kinetics ◽  
Nitridation Reaction ◽  
Result Show ◽  
Different Temperatures ◽  
Two Stages ◽  
Kinetics Of ◽  
And Diffusion

The kinetics of in-situ β- Sialon bonded Al2O3-C (SAC) refractories were investigated by TGA techniques via isothermal nitridation experiments at different temperatures. The result show that the nitridation process of in-situ β-Sialon bonded Al2O3-C refractories can be divided into two stages: the nitridation reaction rate controlling stage in the first 10 min, and the apparent activation energy of nitridation reaction is 370 kJ/mol ; then the reaction is controlled by both chemical reaction and diffusion rate in the following 110 min, the apparent activation energy of nitridation reaction is 410 kJ/mol.

scholarly journals Thermal Properties of Calcium Sulphoaluminate Cement as an Alternative to Ordinary Portland Cement

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 7011
Author(s):  
Małgorzata Gołaszewska ◽  
Barbara Klemczak ◽  
Jacek Gołaszewski
Keyword(s):  
Activation Energy ◽  
Portland Cement ◽  
Apparent Activation Energy ◽  
Thermal Behaviour ◽  
Ordinary Portland Cement ◽  
Isothermal Calorimetry ◽  
Heat Of Hydration ◽  
Curing Temperature ◽  
Cement Pastes ◽  
Calcium Sulphoaluminate

This paper presents the results of research into the heat of hydration and activation energy of calcium sulphoaluminate (CSA) cement in terms of the dependence on curing temperature and water/cement ratio. Cement pastes with water/cement ratios in the range of 0.3–0.6 were tested by isothermal calorimetry at 20 °C, 35 °C and 50 °C, with the evolved hydration heat and its rate monitored for 168 h from mixing water with cement. Reference pastes with ordinary Portland cement (OPC) were also tested in the same range. The apparent activation energy of CSA and OPC was determined based on the results of the measurements. CSA pastes exhibited complex thermal behaviour that differed significantly from the thermal behaviour of ordinary Portland cement. The results show that both the w/c ratio and elevated temperature have a meaningful effect on the heat emission and the hydration process of CSA cement pastes. The determined apparent activation energy of CSA revealed its substantial variability and dependence, both on the w/c ratio and the curing temperature.

scholarly journals The Pozzolanic Activity of the Sediment Treated by the Flash Calcination Method

2021 ◽  
Author(s):  
DUC CHINH CHU ◽  
Mouhamadou AMAR ◽  
Joelle KLEIB ◽  
Mahfoud BENZERZOUR ◽  
Damien BETRANCOURT ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Isothermal Calorimetry ◽  
Pozzolanic Reactivity ◽  
Development Of Resistance ◽  
Physico Chemical ◽  
Flash Calcination ◽  
Alternative Materials ◽  
Different Temperatures ◽  
And Performance ◽  
Calcination Method

Abstract The dredged sediment has been positioned for years as alternative materials in the construction field. However, it is often necessary to apply a treatment to improve their reactivity and performance. This article aims to study the pozzolanic reactivity of fluvial sediment treated by flash calcination method at different temperatures 650 °C, 750 °C, and 800 °C. The physico-chemical, mineralogical, and environmental characteristics were studied for treated (flash-calcined sediment) and raw sediment. The pozzolanic reactivity of the flash-calcined sediments was estimated with Frattini’s test, isothermal calorimetry test, lime consumption analysis and compressive strength then compared to metakaolin which is considered as the reference. The results of the compressive strength of mortars show the detrimental effect of raw sediment on the development of resistance. Contrary to the raw sediment, the treatment of the sediments by flash calcination activates the pozzolanic reactivity of the clay phases and considerably improves the contribution of the sediments to the development of resistance and the porous structure. Moreover, the sediment calcined at 750 °C gives better properties than those obtained at 650 °C and 800 °C. The result demonstrates the feasibility of using calcined sediments as a pozzolanic mineral addition in a cementitious material.

scholarly journals Evaluation of Strength Development in Concrete with Ground Granulated Blast Furnace Slag Using Apparent Activation Energy

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 442 ◽  
Author(s):  
Hyun-Min Yang ◽  
Seung-Jun Kwon ◽  
Nosang Vincent Myung ◽  
Jitendra Kumar Singh ◽  
Han-Seung Lee ◽  
...  
Keyword(s):  
Activation Energy ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Apparent Activation Energy ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
Strength Development ◽  
Replacement Ratio ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

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.

Nuclear magnetic resonance study of proton exchange in the water – 2-propanol system

1970 ◽  
Vol 48 (10) ◽  
pp. 1616-1618 ◽  
Author(s):  
K. C. Tewari ◽  
N. C. Li
Keyword(s):  
Activation Energy ◽  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Proton Exchange ◽  
Electron Donors ◽  
Specific Rate ◽  
Kcal Mole ◽  
Magnetic Resonance Study ◽  
Different Temperatures ◽  
Kinetics Of

The specific rate constants for the reaction[Formula: see text]where ROH is 2-propanol, have been determined at four different temperatures. The activation energy has been calculated to be 10.4 kcal/mole. In addition, the effect of the presence of several electron donors on the kinetics of the reaction has been noted.

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

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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