Using Isothermal Calorimetry to Predict Setting Time of Cement-Based Materials (CBMs)

2021 ◽  
pp. 341-349
Author(s):  
Arvind Vishavkarma ◽  
Kizhakkumodom Venkatanarayanan Harish
Keyword(s):  
Isothermal Calorimetry ◽  
Setting Time ◽  
Cement Based Materials

scholarly journals Influence of the Treatment Temperature on the Microstructure and Hydration Behavior of Thermoactivated Recycled Cement

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3937
Author(s):  
Sofia Real ◽  
Ana Carriço ◽  
José Alexandre Bogas ◽  
Mafalda Guedes
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Mechanical Strength ◽  
Water Demand ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Treatment Temperature ◽  
Diffraction Field ◽  
Resonance Spectroscopy ◽  
Scanning Electron

This paper intends to contribute to a better knowledge of the production and rehydration of thermoactivated recycled cement and its incorporation in cement-based materials. To this end, the influence of the treatment temperature on the properties of recycled cements and recycled cement pastes was assessed by means of a wide array of tests. Anhydrous recycled cement as well as the resulting pastes were characterized through density and particle size, water demand and setting time, thermogravimetry, X-ray diffraction, field emission gun scanning electron microscopy, isothermal calorimetry, 29Si nuclear magnetic resonance spectroscopy, flowability, mechanical strength, mercury intrusion porosimetry and scanning electron microscopy. The treatment temperature had a significant influence on the dehydration and hydration of recycled cement, essentially resulting in the formation of C2S polymorphs of varying reactivity, which led to pastes of different fresh and hardened behaviors. The high water demand and the pre-hydration of recycled cement resulted in high setting times and low compressive strengths. The highest mechanical strength was obtained for a treatment temperature of 650 °C.

scholarly journals Effect of boron-containing aggregates on setting and hardening of Portland cement mortars

2018 ◽  
Vol 163 ◽  
pp. 04003 ◽  
Author(s):  
Aneta Antolik ◽  
Michał A. Glinicki ◽  
Marek Gawlicki
Keyword(s):  
Isothermal Calorimetry ◽  
Setting Time ◽  
Radiation Shielding ◽  
Boron Compounds ◽  
Concrete Technology ◽  
Neutron Shielding ◽  
Mortar Strength ◽  
Cement Mortars ◽  
Isothermal Calorimeter ◽  
Cement Setting

Multicomponent cement-based composites are known as versatile structural materials for enhanced radiation shielding. The use of selected elements, like boron, cadmium, or rare earth elements, provides an increased neutron shielding capacity. Because of profusion, reasonable costs and large cross-section for neutron capture, boron containing minerals are suggested as aggregates for radiation shielding concrete. Despite many advantages, boron additives may act as cement setting retarders. Uncontrolled setting and hardening is not acceptable in radiation shielding concrete technology. In this work we present results from isothermal calorimetry measurements on cement mortars with boron-containing aggregates. Four types of boron aggregates were used in the studies: colemanite, ulexite, borax and boron carbide. Based on calorimetric curves, the beginning of setting time was determined. Additionally early mortar strength was investigated and linear relationship between the heat generated in the isothermal calorimeter and the early compressive strength has been observed. The use of isothermal calorimetry allowed us to estimate the limits for the content of boron compounds to be used cement mortar.

scholarly journals A Mathematical Model for the Electrical Resistivity of Cement Paste at Early Ages Considering the Partially Saturated State

Materials ◽  
2020 ◽  
Vol 13 (15) ◽  
pp. 3306 ◽  
Author(s):  
Ye Tian ◽  
Xin Xu ◽  
Haodong Ji ◽  
Zushi Tian ◽  
Xianyu Jin ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Electrical Resistivity ◽  
Cement Paste ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Degree Of Saturation ◽  
Early Age ◽  
Saturation State ◽  
Partially Saturated ◽  
Saturated State

For cementitious materials, electrical resistivity is often used in the study of the cement hydration process at early age, as one of the few indicators that can be continuously and non-destructively monitored. Variation characteristics of resistivity are widely reported to interact with the early-age performance of cement paste, such as hydration kinetics parameters and setting time. However, there is no reasonable mathematical model to predict the resistivity at early ages, especially within the first 24 h, due to significant changes in the porosity and degree of saturation. In this work, a mathematical model was developed by considering the partially saturated state and density change of C-S-H (calcium silicate hydrate). To verify the model, two experimental methods were chosen, including the non-contact electrical resistivity test and isothermal calorimetry test. The hydration heat and resistivity of cement paste with a water–cement ratio of 0.35 and 0.45 were continuously monitored for 3 days. In the resistivity test, embedded temperature sensors were used to monitor the internal temperature and temperature correction was treated carefully in order to obtain accurate data. The test results prove that the mathematical model can accurately predict electrical resistivity and describe the saturation state of early-age cement pastes under sealed curing.

scholarly journals Effect of Straw Fiber Modification Methods on Compatibility between Straw Fibers and Cement-Based Materials

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Demin Jiang ◽  
Penghui An ◽  
Suping Cui ◽  
Shiguo Sun ◽  
Jingzong Zhang ◽  
...  
Keyword(s):  
Alkali Treatment ◽  
Setting Time ◽  
Treatment Method ◽  
Acrylic Emulsion ◽  
Fiber Modification ◽  
Structural Density ◽  
Fiber Treatment ◽  
Cement Based Materials ◽  
Modification Method ◽  
Alkali Modification

To improve the utilization of crop straws as a resource and the compatibility between straw fibers and cement-based materials, the hydration of modified straw fiber cement-based composite (SFCC) was studied. The structural characteristic of SFCC was investigated by FTIR, SEM, and XRD. The results show that the setting time of several modified straw fiber SFCC pastes was shorter than that of the unmodified straw fiber SFCC paste, and the best method of fiber modification to improve the setting time of the SFCC paste is Na2O·nSiO2 treatment. The recommended fiber modification method for improving the compatibility between straw fibers and cement-based materials is alkali modification, followed by pure acrylic emulsion modification and Na2O·nSiO2 modification. To improve the strength of SFCC, the straw fiber should be modified by alkali, followed by pure acrylic emulsion and Na2O·nSiO2 modification and the method of water modification is also recommended. The phase types and relative contents of crystalline hydration products mixed with the modified straw fiber SFCC are significantly higher than those of the unmodified fiber SFCC. The fiber treatment method that was most helpful to increase the structural density of hydrates of SFCC was alkali treatment and pure acrylic emulsion treatment, followed by Na2O·nSiO2 treatment.

The Early-Age Drying Shrinkage of Cement-Based Materials with the same Workability after Temperature Compensation

2013 ◽  
Vol 405-408 ◽  
pp. 2604-2609
Author(s):  
Li Feng Zhang ◽  
Jun Ying Lai ◽  
Xiao Qian Qian ◽  
Chong Shen
Keyword(s):  
Temperature Compensation ◽  
Setting Time ◽  
Drying Shrinkage ◽  
Concrete Specimen ◽  
Temperature Deformation ◽  
Control Group ◽  
Early Age ◽  
Peak Time ◽  
Initial Setting Time ◽  
Cement Based Materials

The early age drying shrinkage of cement-based materials with same the same workability staring from the initial setting time was studied. Superplasticizers (SP) were used to get the same workability. The drying shrinkage of paste was measured by clock gauge, and CABR-NES deformation instrument was used to measure the shrinkage of concrete. Temperature probes were buried into both paste and concrete specimen cores to measure the temperature curve, and temperature deformation was considered into the early shrinkage. Results show the addition of SP increases much more shrinkage than the control group, and polycarboxylate SP increases more shrinkage than naphthalene SP. The different temperature peak time of different mixtures show that the addition of SP changes the hydration process of cement, and the shrinkage of cement-based materials after temperature compensation is bigger than the measured value in the first 6 hours, but the gap is not big.

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 Evaluation of Self-Consolidating Concrete Robustness by Measuring Electrical Conductivity of Plastic Concrete

2018 ◽  
Author(s):  
Payam Vosoughi ◽  
Mahmoud Motahari Karein
Keyword(s):  
Electrical Conductivity ◽  
Setting Time ◽  
Test Methods ◽  
Test Method ◽  
Fresh Properties ◽  
Conventional Concrete ◽  
Self Consolidating Concrete ◽  
Plastic Concrete ◽  
Cement Based Materials ◽  
Long Time

This paper is aimed to review robustness of Self-Consolidating Concrete (SCC) in term of resistance against static segregation and bleeding. SCC is a highly fluid and non-segregating concrete able to spread through even dense reinforcement and homogenously fill formwork without using any external mechanical consolidation. Due to field requirements, SCC should be able to sustain its desired fresh properties over a relatively long time (about two or three hours) making it more susceptible to segregation than conventional concrete. Although there are a coupleof proposed test methods to evaluate SCC robustness, multi-electrodes electrical conductivity technique could be a reliable, non-destructive, inexpensive and simple test method to continuously monitor progress of hydration reactions (even indicating initial and final setting time) and stability (bleeding and both static and dynamic aggregate segregation) of plastic cement-based materials over the early-age period. In this paper, a brief review on fresh properties of SCC and staticaggregate segregation has been taken place. Then, different methods for measuring concrete conductivity have been investigated. Afterward, some studies on evaluation of stability of cement-based materials and SCC have been reviewed. Finally, based on the literature, some recommendations for future works are introduced.

scholarly journals Effective Absorption Capacity Examined by Isothermal Calorimetry: Effect of Pore Structure and Water-to-Cement Ratio

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Joo-Ha Lee ◽  
Do Guen Yoo ◽  
Bo Yeon Lee
Keyword(s):  
Activated Carbon ◽  
Carbon Fibre ◽  
Pore Structure ◽  
Isothermal Calorimetry ◽  
Absorption Capacity ◽  
Cement Ratio ◽  
Effective Absorption ◽  
Water To Cement Ratio ◽  
Cement Based Materials ◽  
Activated Carbon Fibre

The accurate measurement of effective absorption capacity is crucial for highly absorptive materials when they are used within cement-based materials. In this study, a method for examining effective absorption capacity using isothermal calorimetry is reviewed and investigated in detail to accommodate different circumstances. Specifically, the effect of different pore structures and water-to-cement ratios in determining effective absorption capacity is experimentally examined using activated carbon fibre and powdered activated carbon. The results suggest that the method may be suitable for porous materials with micropores but not suitable for those with mesopores. Also, the results indicate that the effective absorption capacity value can change with the water-to-cement ratio used. These findings can be used to find the effective absorption capacity of highly absorptive materials more accurately using the isothermal calorimetry method.

scholarly journals Hardening phenomenon of Portland cement suspensions monitored by Vicat test, isothermal calorimetry and oscillatory rheometry

2018 ◽  
Vol 11 (5) ◽  
pp. 949-959 ◽  
Author(s):  
R. C. O. ROMANO ◽  
M. A. CINCOTTO ◽  
R. G. PILEGGI
Keyword(s):  
Blast Furnace ◽  
Chemical Reactions ◽  
Blast Furnace Slag ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Limestone Filler ◽  
Mineral Addition ◽  
Oscillatory Rheometry ◽  
First Contact ◽  
Furnace Slag

Abstract This work was conducted to evaluate the hardening phenomenon of pastes formulated with Portland cements blended with limestone filler (CPIIF), ground blast furnace slag (CPIIE) or pozzolan (CPIIZ). Vicat test, isothermal conduction calorimetry and oscillatory rheometry were the methods used to monitor this transition. The results of Vicat test indicates the faster setting time of pozzolan cement, but no information before this time was obtained. Using isothermal calorimetry was possible to monitor the related changes to the chemical reactions since the first contact with water, and using rheometry, the rate and force of cement particles agglomeration. The main purpose of this work was not extensively explain the results of these three methods, but show that they are complementary to better explain the transition from fluid-to-solid behavior in function of different kind of mineral addition.

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