Hydration Heat Temperature Research Articles

Evaluate the effect of coarse aggregates on cement hydration heat and concrete temperature modelling using isothermal calorimetry

The early-age temperature rise in concrete, induced by cement hydration, poses a significant risk of thermal cracking. Accurate prediction of concrete hydration temperature is essential for thermal cracking prevention. Cement hydration heat obtained from isothermal calorimetry has been applied to concrete temperature modelling by previous studies. Isothermal calorimetry often excludes coarse aggregates due to the calorimeter capacity limitations, assuming mortar hydration heat can represent concrete, which may neglect the hydration delay effect of coarse aggregates. This study uses an isothermal calorimeter capable of accommodating coarse aggregates to measure the hydration heat of concrete and equivalent mortar, evaluating the validity of this assumption. Results show that the 3-day cumulative hydration heat of concrete exceeds that of mortar, especially at elevated curing temperatures. Significant differences were found in the activation energy and hydration parameters between concrete and mortar, indicating that the presence of coarse aggregates affects samples’ temperature sensitivity and hydration heat development. Concrete temperature finite element modelling, validated by semi-adiabatic calorimetry, demonstrates that models based on concrete isothermal calorimetry data provide higher accuracy than those based on mortars. This study demonstrates that the hydration heat development, activation energy, and hydration parameters differ significantly between mortar and concrete. Concrete temperature models based on mortar hydration heat data can result in prediction errors exceeding 5 %. This study recommended employing micro-concrete samples in isothermal calorimetry to replicate actual concrete mixes.

Mechanical response of long-span CFST arch bridges based on the hydration heat temperature effect

As the span of concrete-filled steel tube (CFST) arch bridges increases, the hydration heat temperature effect of concrete inside steel tube becomes more severe, which increases the safety risk during the construction process. Therefore, a numerical simulation of the mechanical response of a long-span CFST arch bridge under the influence of hydration heat was carried out. First, based on the hydration heat conduction theory, a finite element model of the transient temperature field of a CFST arch rib was established. The temperature distribution of the CFST arch rib and its variation with time were revealed, and an approximate formula for the distribution of the hydration heat temperature along the radial direction of the CFST was provided. Subsequently, the variation law of the thermal stress of a CFST during hydration heat release was investigated. Finally, based on the principle of temperature equivalence, a finite element model of the overall CFST arch rib was established to examine the effect of hydration heat on the deformation of the arch rib. The results reveal that the hydration heat temperature field of the CFST arch rib exhibits nonlinear and axisymmetric characteristics. The maximum temperature of the section and the maximum temperature difference can reach 73.5 °C and 33.2 °C, respectively. Because of the influence of the hydration heat, there is a significant stress gradient in the cross section of the arch rib. A maximum radial stress of 2.08 MPa is attained, indicating a risk of concrete cracking. Additionally, the displacement along the transverse and vertical directions of the chord tube exhibits an initial increase, followed by a decrease over time. The maximum transverse displacement of the chord tube reaches 70.6 mm, while the vertical displacement reaches 117.8 mm.

Numerical simulation investigation on hydration heat temperature and early cracking risk of concrete box girder in cold regions

Numerical simulation investigation on hydration heat temperature and early cracking risk of concrete box girder in cold regions

Early hydration heat temperature field of precast concrete T-beam under steam curing：Experiment and simulation

Precast concrete T-beam steam curing can improve production efficiency, realize large-scale production of T-beams, and achieve better economic benefits. We performed tests and numerical simulations on a 30-meter-long full-size precast concrete T-beam to study the economical and reasonable steam curing scheme. The study found that in the early stages of steam curing, the temperature at the mid-span section increases faster than that at the end-span section. The highest temperatures of the tested beams were found in end-span section., and the core-surface temperature difference increased and then decreased, with the maximum temperature difference occurring at the junction of the top and web slabs of the concrete T-beam. To meet initial prestress tensioning requirements, the steam curing of increasing the temperature for 2 h to 50 ℃, keeping the temperature constant for 7 h, and cooling the temperature for 1 h is the most economical scheme, as seen from the comparison and analysis of the development law of concrete hydration heat temperature and the results of concrete test blocks under the same curing. Under this steaming scheme, the end-span section of the concrete T-beam reached a peak temperature of 68.5 °C at 14 h, and the core-surface temperature difference reached a maximum of 8.6 °C at 4.5 h; the peak temperature of the mid-span section was 60.2 °C, with a maximum temperature difference of 8.3 °C. In order to accurately predict the law of T-beam concrete temperature development under steam curing, two subprograms, HETVAL and UMATHT, were compiled on the ABAQUS secondary development platform. When calculating by natural age t, the maximum differences between the measured peak values and the peak values calculated by HETVAL and UMATHT were 30.0% and 27.7%, respectively. After considering the equivalent age te of concrete, the maximum differences between the measured peak values and the peak values calculated by HETVAL and UMATHT were 8.2% and 1.9%, respectively. Therefore, the UMATHT subprogram, considering equivalent age and hydration degree, can accurately predict the development of the concrete hydration heat temperature field under the steam curing process.

Study on Optimization of Cooling System for Mass Pier Column of Shenzhong Passage Non-navigable Bridge

In this paper, the optimization layout of cooling pipes and the measured temperature field of the mass pier column for the Shenzhong Passage non-navigable bridge are carried out, and the finite element modeling software is utilized to simulate the whole construction process, and the temperature time and process model is established for simulation analysis. The results show that the measured hydration heat temperature field in the field construction meets good agreement with the simulation results. The optimized cooling pipe layout scheme saves more raw materials and elbows, and shorts the project construction period; It can realize more effective internal lowering and external protection for the construction of mass concrete structures of piers and columns, which is especially suitable for the maintenance of sea-crossing bridges in windy environmental conditions; The temperature-induced cracks are effectively controlled, which can provide a reference for similar projects.

Temperature Control for Mass Concrete of Bridge Cap in Summer Construction

In order to realize the accurate calculation of the temperature field of concrete hydration heat, the paper takes the concrete hydration heat temperature field of the pile cap of Liexi Bridge as a case for simulation analysis. Firstly, a three-dimensional finite element model of concrete hydration heat temperature field is established; Then, the temperature field of the hydration heat of the concrete cushion cap of the Liexi Bridge is simulated. The experimental results show that the maximum actual measured temperature of the core point of concrete hydration heat temperature is 63.1 °C, and the corresponding calculated temperature is 62.2 °C. The maximum actual measured temperature of the surface point is 54.8 °C, and the corresponding calculated temperature is 53.8 °C. The maximum temperature difference between inside and outside is 18.9 °C, and the corresponding calculated temperature is 13.4 °C. The research results show that the calculation model has high accuracy

Temperature Control for Mass Concrete Construction of Wentang Bridge 5# Pier Pile Cap in Winter Construction

In order to ensure the construction quality of mass concrete structures in winter, and avoid and prevent harmful temperature cracks of mass concrete, a calculation method of temperature field of hydration heat in winter based on finite element method is proposed in this paper. First, the three-dimensional finite element model of the temperature field of hydration heat is established; Then, the temperature variation of winter hydration heat temperature field of Wentang Bridge is calculated through experiments. The results show that the maximum measured temperature of the core point is 44.2 °C, and the corresponding calculated temperature is 53.7 °C. The maximum internal and external temperature difference measured is 24.7 °C, and the corresponding calculated temperature is 22.4°C. The research results prove that the calculation model can better simulate the concrete hydration process.

Temperature Field of Concrete‐Filled Steel Tubular Arch Bridges and Its Application

This study aimed to reveal the evolution rule and influence mechanism of temperature field and its effect of long‐span concrete‐filled steel tubular arch bridges in a plateau area. The temperature field and its effect of large‐diameter concrete‐filled steel tubular arch bridges under strong radiation, hydration heat, and large temperature difference were studied using the ANSYS transient thermal analysis method. The optimization method on transverse perfusion sequence and perfusion‐time interval considering temperature effect was proposed based on stress influence line, equivalent age theory, and energy method. Results showed that the temperature field along the radial direction distributes as a symmetrical three‐segment polyline with an influence depth of D/4 under ambient temperature and hydration heat, and it distributes as an asymmetric three‐segment polyline with an influence depth of D/8 under solar radiation, ambient temperature, and hydration heat, and this is smaller than the specified value of D/4. The maximum temperature on the sunny side is about 20°C higher than that on the shaded side. The influence of solar radiation absorption coefficient and ambient temperature on the maximum temperature gradient and maximum stress is greater than that of wind speed. The optimization method on transverse perfusion sequence and perfusion‐time interval considering temperature effect proposed in this paper is reasonable and convenient for engineering applications.

Mechanical properties and hydration process of steel slag-cement binder containing nano-SiO2

Research on low-heat cement (LHC) was significant for the preparation of mass concrete. However, the low early strength was one of the difficulties during the engineering applications. In present study, steel slag (SS) was used to produce LHC, and nano-SiO2 (NS) was added to promote the early strength development. Cement was replaced by SS, and NS was further added into the cement-SS binder. Setting time, fluidity, and compressive strength were researched; hydration process and hydrates were also studied by hydration heat, hydration temperature, XRD, TGA, and NMR; microstructure was characterized by MIP and SEM. Results showed that SS reduced the early hydration heat of cement significantly, and meanwhile the compressive strength was reduced and the porosity was increased obviously. However, the addition of NS into cement-SS binder promoted the early strength, which was equivalent to that of single cement, and more importantly the increase on hydration heat and hydration temperature was few. The use of SS reduced the Ca(OH)2 content of cement due to the dilution effect; the addition of NS decreased the Ca(OH)2 content of cement-SS binder owing to the pozzolanic reaction. Indeed, the hydration degree between cement and cement-SS-NS binder was very close. Furthermore, the harmless pore volume of cement-SS binder was increased evidently because of the addition of NS. This research proved that reactive nano materials was efficient to promote the early strength of LHC.

Preparation, characterization, investigation of phase change micro-encapsulated thermal control material used for energy storage and temperature regulation in deep-water oil and gas development

Based on the requirements of low hydration heat and maximum temperature of cement slurry used in deep-water natural gas hydrate formation, a novel cement slurry containing phase change micro-encapsulated thermal control material was prepared and investigated. Firstly, a novel phase change micro-encapsulated thermal control material (Micro-P1) was synthesized and studied. It was found that the Micro-P1 have spherical structure and the particle diameter is 2.664 μm, the phase change properties, thermal conductivity, mechanical properties and hydrophilicity of Micro-P1 were significantly improved by nano-SiO2. Secondly, the Micro-P1 was introduced into cement slurry, and the controlling effects of Micro-P1 on the heat development of cement slurry was investigated. Moreover, the innovation of this study is that based on the established heat transfer decomposition model of hydrate, the influences of different cement slurry on the stability of hydrate were quantitatively calculated. The results show that the maximum temperature was reduced by 9.3 °C, the hydration heat of 24 and 48 h was reduced by 26.9 and 12.78%. Especially, the quantitative calculation shows that when the decomposition interface moves distance is 0.30 m, the required time was increased by 30.6%, in other words, the stability of hydrate was obviously improved.

Study on temperature control and crack resistance of mass concrete anchorage in suspension bridge

This paper aims to study the temperature control of mass concrete, and to understand concrete pouring of hydration heat temperature field and temperature stress distribution. The influence of relevant parameters on reducing the temperature difference between inside and outside and the concrete temperature control and crack resistance measures are put forward. Taking Fuma Yangtze River Bridge as the engineering background, the combining of engineering measurement, theoretical calculation, and ANSYS numerical simulation is adopted. Results show that the use of ANSYS simulation for the mass concrete casting process is feasible. Furthermore, it is concluded that the cracks of mass concrete are prone to appear at the corner of the surface, and the influences of t input temperature, mixing ratio on reducing the internal and external temperature difference are also studied.

Curing parameters’ influences of early-age temperature field in concrete continuous rigid frame bridge

The unstable change of early temperature field during concrete curing of box girder could lead to the thermal deformation and autogenous shrinkage deformation of concrete, make the concrete crack early, and even affect the subsequent mechanical performance. In order to study the variation law of the early-age temperature field of the box girder concrete and to seek the method to control the variation of the temperature field of the box girder concrete, the No.0 box segment with the most complex structure and the largest volume in the bridge was selected as the research object. The early-age temperature field of No.0 box segment after pouring was simulated by Midas/FEA and the correctness of the simulation was verified by field measurement. Then the time-history law of early-age temperature field of the box girder under the coupling effect of hydration heat and ambient temperature was studied, and the time-history law of the early-age temperature field of the box girder was investigated by changing different concrete curing parameters. The results show that the larger the local size is, the larger the temperature difference is. The selection of formwork's material and thickness should integrate the factors of formwork bearing capacity and thermal insulation performance. The reasonable selection of formwork can effectively control the core temperature and the temperature difference between the inside and outside of the box girder. Formwork installation temperature and wind velocity have a great influence on the temperature difference between the inside and outside of the box girder. The research results can provide technical support for controlling the early-age temperature field changes of box girder concrete, be used to provide a theoretical basis for the best selection of formwork and the selection of the best concrete curing conditions, and help to improve efficiencies in the uses of human capital, energy, and building materials in engineering construction.

Hydration Heat Analysis and Temperature Control on Steel Shell Concrete Immersed Tube during Precasting

In order to support the high-precision and high-quality prefabrication of steel shell concrete immersed tube for Shenzhen-Zhongshan Bridge, this paper analyzes the influence of temperature field produced by concrete hydration heat on the deformation and local stress of steel shell concrete immersed tube considering the influence of strength time-varying, autogenous shrinkage and creep of concrete and casting technology. Then, this paper puts forward the temperature control index of concrete molding based on the control requirements deformation and local stress of immersed tube. The results show that: the hydration heat of concrete is beneficial to the deformation control of steel shell concrete immersed tube, and it has little influence on the final deformation, the molding temperature of concrete should be controlled below 3°C of the ambient temperature to prevent the cracking of steel concrete interface of immersed tube. The research results of this paper have been applied to the control of concrete casting process of steel shell concrete immersed tube for Shenzhen-Zhongshan Bridge, which can make up for the domestic research blank and provide technical reference for similar projects.

Effect of Thermal Parameters on Hydration Heat Temperature and Thermal Stress of Mass Concrete

To explore the influence of concrete thermal parameters on the hydration heat temperature and thermal stress of mass concrete, four feature positions of a dam foundation were chosen to analyze the changing process of temperature and stress by varying the thermal parameters, including the thermal conductivity, specific heat, surface heat diffusion coefficient, temperature rise coefficient, solar absorption coefficient, and thermal expansion coefficient. Some conclusions were obtained as follows. Increasing the thermal conductivity and reducing the specific heat and temperature rise coefficient of concrete can effectively reduce the maximum temperature of the central concrete structure. Increasing the solar absorption coefficient, specific heat, and thermal expansion coefficient and reducing the thermal conductivity, surface heat diffusion coefficient, and temperature rise coefficient of concrete can reduce the maximum principal tensile stress in the structure to a certain extent. The maximum principal tensile stress at different positions of the structure has a linear functional relationship with the thermal conductivity, specific heat, and thermal expansion coefficient and has a quadratic function relationship with the surface heat diffusion coefficient, temperature rise coefficient, and solar absorption coefficient. Besides, this study also proposed a series of related anticracking measures. This study was expected to provide a theoretical reference for the design, construction, and cracking disease prevention of mass concrete structures.

Preparation and evaluation of micro-encapsulated thermal control materials for oil well cement slurry

Abstract In the process cementing of deep water, cement particles react with water to produce a lot of hydration heat, which can lead to decomposition of natural gas hydrate. We synthesized a kind of micro-capsule thermal control material with paraffin wax as the base material and calcium carbonate as the skeleton support material. At first, the chemical structure and chemical element composition of thermal control material were obtained by FTIR and EDS, respectively. Secondly, the phase change properties of MPCM-1 were measured by using DSC. As a result, it was shown that phase change temperature and phase change enthalpy of thermal control material is 31.11 °C and 88.59 J/g, respectively. Simultaneously, the thermal stability of IPCM-1 was obtained by using a synchronous thermal analyzer. Then, the micro-encapsulated thermal control material is introduced into the cement slurry system, and the hydration heat and maximum hydration temperature rise of the cement slurry were investigated by a self-made hydration heat test device. As a result, compared with cement slurry CB, the hydration heat released to the environment by cement slurry CS12.0% decreased by 44.16% (at 48 h), and the maximum hydration temperature of cement slurry CS12.0% is reduced by 25.4 °C. Besides, compared with cement slurry CB, the compressive strength of cement slurry CS12.0% increased by 5.9% (24 h) and 9.8% (48 h). The thermal control material was added into the cement slurry, and a low hydration heat cement slurry system was successfully prepared.

Preparation of low hydration heat cement slurry with micro-encapsulated thermal control material

During the cementing process of natural gas hydrate (NGH) layer, the hydration heat of cement slurry can easily cause decomposition of NGH which leads to cementing risk. A thermal control material of phase change micro-capsule (PCM-1) with paraffin as the core material and urea-formaldehyde resin as the wall material was successfully synthesized, and then a low hydration heat cement slurry was prepared by using PCM-1. The basic performances of PCM-1 were characterized by using DSC, FTIR, SEM and TG, and the results show that the performances meet designed requirements. Then, the PCM-1 was introduced into cement slurry system, and the hydration heat (Q) and hydration temperature rise (Tr) were measured by using the self-developed semi-adiabatic test equipment. As a result, it was confirmed that the Q and the Tr decrease with the increase of PCM-1 content. The Tr of cement slurry CP15% was 25.4 °C, lower than that of cement slurry CB. Meanwhile, compared with cement slurry CB, at 24 and 48 h hydration heat of cement slurry CP15% were decreased by 7.68 × 104 and 7.28 × 104 J, respectively. Therefore, the decomposition of NGH was avoided attribute to the smaller Q of cement slurry, and the cementing operation risk in deep water was reduced.

Influence of additives on hydration heat of mass concrete

In this paper, the development of early hydration heat and the performance of large temperature difference of mass concrete structures are studied. Five mass concrete samples with two strength grades and five mixing ratios were made. The size of samples is 1000mm∗1000mm∗1400mm. Temperature sensors are embedded in the component while the components are constructed. Temperature of early hydration heat temperature rise and instant heating on one side are tested by the sensors. It is found that the early hydration heat temperature rise of self-made crack resistance concrete with internal curing agent or shrinkage reducing agent is lower than that of common commercial concrete. The results of single-side instantaneous temperature rise test show that the temperature changes least on the heating surface of concrete and most in the middle position.

Simulation analysis of the hydration heat of large diameter CFST arch and its effects on loading age

The hydration heat of pumped concrete in large diameter concrete-filled steel tube (CFST) arches results in considerable temperature changes, which significantly affect the development of the mechanical properties of concrete during its hardening process, making it hard to determine the loading age. Based on the heat conduction theory and finite element method, the hydration heat temperature field of large diameter CFST arches during the period of construction was analyzed. Subsequently, the effects of hydration heat on the developments of compressive strength (fcu) and elastic modulus of concrete (Ec) were analyzed by using the equivalent age method. The results reveal that, because of the influence of the hydration heat, the developments of fcu and Ec are uneven along the radial direction of the arch cross section in the early stage, i.e. faster at the concrete center, and slower at the concrete edge. On the 5th day, the average values of fcu and Ec reach 81.6% and 90.3% of their characteristic values, respectively; the difference of fcu and Ec between the concrete center and concrete edge are 13% and 7.3%, respectively; and fcu, Ec of the concrete cross section tend to be uniform. Hence, in order to ensure structural safety, the loading age for large diameter CFST arches after concrete casting should not be less than 5 days at low ambient temperature.

Retraction Notice: Experimental Research on the Hydration Heat Temperature Field of Hollow Concrete Piers

Measuring points were observed continuously to reveal the hydration heat temperature distribution of hollow concrete bridge pier. The results showed that as the thickness of the pier increased, the central temperature of the pier in- creased significantly due to hydration and the heat was difficult to be dissipated. The hydration temperature accounted for up to 70% of the maximum temperature rise during 20 h and reached the maximum temperature at 24 h after pouring the concrete. There was a jump value between the central temperature and surface temperature in a short period after remov- ing the framework. The jumping was the most dangerous moment for the cracking of pier surfaces. Therefore, the form- work removal time has to be determined prudently and corresponding measures have to be conducted to reduce the possi- bility of pier surface cracking.

Experimental Research on the Hydration Heat Temperature Field of Hollow Concrete Piers

Measuring points were observed continuously to reveal the hydration heat temperature distribution of hollow concrete bridge pier. The results showed that as the thickness of the pier increased, the central temperature of the pier increased significantly due to hydration and the heat was difficult to be dissipated. The hydration temperature accounted for up to 70% of the maximum temperature rise during 20 h and reached the maximum temperature at 24 h after pouring the concrete. There was a jump value between the central temperature and surface temperature in a short period after removing the framework. The jumping was the most dangerous moment for the cracking of pier surfaces. Therefore, the formwork removal time has to be determined prudently and corresponding measures have to be conducted to reduce the possibility of pier surface cracking.