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

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

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).

EFFECT OF PETROLOGICAL FEATURES ON MECHANICAL PROPERTIES OF ROCK SALT FROM THE LGOM (LEGNICA–GŁOGÓW COPPER DISTRICT)

2016 ◽  
pp. 51-64 ◽  
Author(s):  
Katarzyna CYRAN ◽  
Tomasz TOBOŁA ◽  
Paweł KAMIŃSKI
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Uniaxial Compressive Strength ◽  
Rock Salt ◽  
Fluid Inclusions ◽  
Mechanical Parameters ◽  
Research Results ◽  
Strength Tests ◽  
Crystal Boundaries

The paper presents the attempt to find a correlation between the content of impurities and mechanical parameters of rock salt from the LGOM. Research was carried out in three steps: uniaxial compressive strength tests, determination of the content of insoluble minerals (impurities), and observations under the microscope and Raman microspectroscopy. The research results reveal that the rock salt which is characterized by low content of insoluble minerals (0.13–2.11% wt.) shows no correlation between the mechanical properties and the content of impurities. However, it was found that mechanical properties depend on both the distribution of impurities in halite crystals and the presence of fluid inclusions and hydrocarbons along the crystal boundaries. Moreover, the distribution of anhydrite at the edges of halite crystals may influence an increase of rock salt strength. On the contrary, the presence of fluid inclusions and hydrocarbons along the halite crystal boundaries may reduce the rock salt strength.

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.

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 Activation Energy for the Concrete Maturity Model – Part 1: Compressive Strength Tests at Different Curing Temperatures

2020 ◽  
Vol 62 (1) ◽  
pp. 87-106
Author(s):  
Claus Vestergaard Nielsen ◽  
Martin Kaasgaard
Keyword(s):  
Activation Energy ◽  
Compressive Strength ◽  
Laboratory Tests ◽  
Curing Temperature ◽  
Early Age ◽  
Maturity Model ◽  
Arrhenius Model ◽  
Equivalent Age ◽  
Strength Tests ◽  
Concrete Maturity

AbstractThe article addresses the modelling of the maturity of concrete. The apparent activation energy is the backbone of the Arrhenius model, which is typically used to model the maturity of concrete. The maturity (or the equivalent age) is influenced by the curing temperature and it is applied when modelling the hydration process and the hardening of concrete for instance in order to forecast the early-age strength to determine the time for removal of formwork or the time for prestressing. Part 1 of the article describes the background for the maturity model and the test series carried out at the DTI concrete lab.Laboratory tests at different curing temperatures (from 5°C to 60°C) are presented and the compressive strength results are modelled according to the original Freiesleben Hansen and Pedersen maturity model that has been applied in the field for many years. The tests include five different concretes, using three different cement types and the addition of fly ash. There are significant differences especially when considering the later-age strength modelling at either low temperatures or at high temperature curing.

Determination of the Apparent Activation Energy of Concrete by Adiabatic Test

2011 ◽  
Vol 477 ◽  
pp. 411-417
Author(s):  
Jia Chun Wang
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Temperature Rise ◽  
Adiabatic Temperature Rise ◽  
Study Results ◽  
Stage Development ◽  
Concrete Hydration ◽  
Apparent Activation Energies ◽  
Influence Of Hydration

It is known that apparent activation energy of the binders in concrete characterizes the sensitivity of concrete hydration processes to temperature. In this paper the apparent activation energies of concretes containing different complex binders have been determined through adiabatic temperature rise test. The influence of hydration emission heat on the apparent activation energy of concrete is studied. The study results show that the apparent activation energy is decreasing with the hydration of binder stage development.

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