Effect of Hydration Heat Inhibitor on Thermal Stress of Hydraulic Structures with Different Thicknesses

Concrete hydration heat inhibitor can inhibit the early hydration reaction of concrete and reduce the initial heat release of concrete. However, there is no in-depth research on the effect of hydration heat inhibitor on hydraulic structures with different thicknesses and constraints. In this paper, numerical simulation is used to study the change of temperature and stress field after adding hydration heat inhibitor by establishing the finite element models of tunnel lining, sluice, and gravity dam. The results show that the effect of the hydration heat inhibitors on reducing the temperature peak is inversely proportional to the thickness of the structure. A formula is put forward to evaluate their relation in this paper. When the thickness of the structure is about 6 m, there is no peak cutting effect. For the stress field, hydration heat inhibitor can greatly reduce the thermal stress of the thin-walled structure and make the structure meet the temperature control requirements; for the medium wall thickness structure, it can reduce the internal tensile stress about 50% and the surface tensile stress about 20%, and other temperature control measures are still needed to ensure that the surface tensile stress of the structure meets the requirements; for hydraulic structures with large volume and thickness, the application effect of the inhibitor has limitations, which can reduce the internal tensile stress about 30%, but the tensile stress in the surface area will increase about 7% due to the increase of the internal and external temperature difference; therefore, other temperature control measures such as arranging cooling water pipe, strengthening surface insulation, and so on are needed to ensure that temperature cracks do not occur. This paper provides references and suggestions for the research and engineering application of hydration heat inhibitor.

Download Full-text

Study on Temperature Field and Construction Monitoring of Hydration Heat of Railway Cable-Stayed Bridge Pile Cap

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.243-249.1589 ◽

2011 ◽

Vol 243-249 ◽

pp. 1589-1596

Author(s):

Xu Hui He ◽

Hao Cheng ◽

Hong Xi Qin

Keyword(s):

Temperature Field ◽

Thermal Stress ◽

Temperature Control ◽

Structural Reliability ◽

Control Measure ◽

Time History ◽

Hydration Heat ◽

Control Measures ◽

Mass Concrete ◽

Pile Cap

The temperature control of mass concrete is regarded to be a universal problem. Because of the heavy load of railway cable-stayed bridges, the pile caps usually have large dimensions, so the thermal stress, which is caused by hydration heat, must be emphasized. In order to study the spatial distribution of temperature in mass concrete and find a functional temperature control measure during construction, the theoretical and FEM analysis of hydration heat-thermal stress field are applied, which can improve structural reliability and provide reference for design and engineering of the similar project. Based on FEM calculation, the theoretical hydration heat temperature field is obtained. In the same time, the temperature sensors as well as strain sensors are arranged in the key position of pile cap. Then the variation of hydration temperature in concrete would be measured and recorded since the concrete is pouring. According to the theoretical simulation and the monitoring results, the time-history curve of hydration heat is obtained, and the variation of inner temperature gradient along the height direction as well as the longitudinal direction with the concrete age are studied, and the feasibility of temperature control measures is also verified.

Download Full-text

Study of the Volume Deformation and Stress Development of Concrete Influenced by the Different Cooling Rate

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.744-746.1495 ◽

2015 ◽

Vol 744-746 ◽

pp. 1495-1498

Author(s):

Yi Fang ◽

Xue Feng Song ◽

Long Chen

Keyword(s):

Thermal Stress ◽

Cooling Rate ◽

Temperature Control ◽

Control Measures ◽

Stress And Strain ◽

Stress Tests ◽

Volume Deformation ◽

Cooling Rates ◽

Stress Development ◽

Concrete Placement

This paper studied the development of stress and strain influences by different cooling rates based on the concrete thermal stress tests. furthermore, discussed the temperature control measures for early concrete placement.

Download Full-text

Effects of Expansive Agents on the Early Hydration Kinetics of Cementitious Binders

Materials ◽

10.3390/ma12121900 ◽

2019 ◽

Vol 12 (12) ◽

pp. 1900 ◽

Cited By ~ 2

Author(s):

Miao Miao ◽

Qingyang Liu ◽

Jian Zhou ◽

Jingjing Feng

Keyword(s):

Fly Ash ◽

Hydration Heat ◽

Mineral Admixture ◽

Mineral Admixtures ◽

Hydration Reaction ◽

Hydration Kinetics ◽

Early Hydration ◽

Expansive Agent ◽

Mechanical Performances ◽

Kinetics Of

The addition of expansive agents could overcome the main disadvantages of raw concrete including high brittleness and low tensile strength. Few studies have investigated the early hydration kinetics of expansive cementitious binders, though the findings from the early hydration kinetics are helpful for understanding their technical performances. In this study, mixtures of 3CaO•3Al2O3•CaSO4 and CaSO4 (i.e., ZY-type™ expansive agent) with different proportions of mineral admixtures (e.g., fly ash and slag) were added into cement pastes to investigate the early hydration kinetics mechanism of expansive cementitious binders. Early hydration heat evolution rate and cumulative hydration heat were measured by isothermal calorimeter. Kinetic parameters were estimated based on the Krstulovic–Dabic model and Knudsen equations. Mechanical performances of expansive cementitious binders were tested in order to evaluate if they met the basic requirements of shrinkage-compensating materials in technical use. The early hydration heat released from cementitious binders containing ZY-type™ expansive agent was much greater than that released by pure cement, supporting the idea that addition of the expansive agent would improve the reaction of cement. The early hydration kinetic rates were decreased due to the reactions of the mineral admixture (e.g., fly ash or slag) and the ZY-type™ expansive agent in the cement system. The hydration reaction of cementitious binders containing ZY-type™ expansive agent obeyed the Krstulovic–Dabic model well. Three processes are involved in the hydration reaction of cementitious binders containing ZY-type™ expansive agent. These are nucleation and crystal growth (NG), interactions at phase boundaries (I), and diffusion (D). The 14-day expansion rates of cementitious binders containing ZY-type™ expansive agent are in the range of 2.0 × 10−4 to 3.5 × 10−4, which could meet the basic requirements of anti-cracking performances in technical use according to Chinese industry standard JGJ/T 178-2009. This study could provide an insight into understanding the effects of expansive agents on the hydration and mechanical performances of cementitious binders.

Download Full-text

Dynamic Simulation Analysis of Temperature Field and Thermal Stress of Concrete Gravity Dam during Construction Period

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.90-93.2677 ◽

2011 ◽

Vol 90-93 ◽

pp. 2677-2681 ◽

Cited By ~ 1

Author(s):

Hai Bo Wang ◽

Sheng Qiang ◽

Xiao Sun ◽

Rui Zheng

Keyword(s):

Temperature Field ◽

Thermal Stress ◽

Stress Field ◽

Dynamic Simulation ◽

Temperature Control ◽

Simulation Analysis ◽

Water Diversion ◽

Gravity Dam ◽

Good Effect ◽

Concrete Gravity Dam

The basic theory of temperature field and stress field of concrete and 3D FEM combining with cooling pipe discrete model and iteration method are used to carry out the dynamic simulation analysis of the temperature filed and stress field of a concrete gravity dam of South-to-North Water Diversion Project. The impacts on cracking mechanism of the surface insulation, internal cooling and environmental climate are considered in calculation. The change laws of temperature field and thermal stress with time and their distributions are analyzed, reasonable temperature control measures are put forward for reference. The results show that good effect of temperature control and cracking prevention is achieved, the proposed measures should have great reference significance to the similar concrete dam in future.

Download Full-text

Temperature-stress coupling mechanism analysis of one-time pouring mass concrete

Thermal Science ◽

10.2298/tsci180825231y ◽

2019 ◽

Vol 23 (3 Part A) ◽

pp. 1615-1621 ◽

Cited By ~ 1

Author(s):

Ben-Gao Yang ◽

Peng He ◽

Gao-You Peng ◽

Tong Lu

Keyword(s):

Stress Field ◽

Temperature Stress ◽

Temperature Control ◽

Damage Control ◽

Control Measures ◽

Effect Of Temperature ◽

Actual Condition ◽

Coupling Mechanism ◽

Mass Concrete ◽

Finite Element Software

Thermal damage control of mass concrete is the key to guarantee the quality of mass projects. Based on several engineering experiences and finite element software ANSYS, the temperature field and stress field of the typical dam section of the Tengzigou hydropower station in Sichuan province were simulated. Considering the actual materials used, cooling measures, etc., maximum tensile stress and compressive stress at different time points derived from the temperature stress field during the time of concrete maintenance were calculated, and the numerical results showed that strength increment under the given conditions was much less than the actual condition. After the concrete of the dam body of the hydro power station were poured, there was no significant temperature stress crack appeared through a long-term observation, and the project condition was in tune with the calculated expectation. The above research results are valuable to further prediction of concrete temperature in different periods, the pre-study of the effect of temperature control measures, and these could offer guidance of the adjustment of temperature control measures in the case of abnormal conditions.

Download Full-text

CAE Simulation Study on Thermal Stress of Butterfly Valve and Actuator

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.532.301 ◽

2014 ◽

Vol 532 ◽

pp. 301-306

Author(s):

Xiao Bo Tian ◽

Jin Tang Yang ◽

Dan Meng

Keyword(s):

Thermal Stress ◽

High Temperature ◽

Temperature Control ◽

Simulation Study ◽

Hot Rolling ◽

Control Measures ◽

Butterfly Valve ◽

Hot Air ◽

Hot Rolled ◽

Cae Simulation

To the valve system in the furnace hot air duct of the hot-rolled furnace in steel, the thermal Stress of butterfly valve and actuator was simulated by ANSYS. The feasibility of appropriate temperature control measures of too high temperature of butterfly valve and actuator was verified. And in the field, the transformation and the temperature measurement of butterfly valve and actuator were performed; the failure rate was calculated, to ensure that butterfly valve and actuator could meet the requirements of hot rolling.

Download Full-text

FEM Study of Thermal Stress Field of Wheel under Typical Braking Condition

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.378.51 ◽

2013 ◽

Vol 378 ◽

pp. 51-54

Author(s):

Ping Wang ◽

Wei Li ◽

Wen Chen ◽

Dong Ming Wang

Keyword(s):

Thermal Stress ◽

Stress Field ◽

Tensile Stress ◽

Transient Temperature ◽

Emergency Braking ◽

Transient Temperature Field ◽

Thermal Stress Field ◽

Actual Load ◽

Element Theory ◽

Load Conditions

Based on actual load conditions, the transient temperature field and thermal stress field of rail wheel under the conditions of service braking, emergency braking and ramp braking are calculated by means of the finite element theory. As a result, the inner side of web hole is in a prolonged condition of tensile stress, while the outside of web hole is in the condition of compressive stress, where the value of tensile stress is maximal under ramp braking. Furthermore, the value of thermal stress for worn 20mm wheel is obviously higher than that for non-worn wheel.

Download Full-text

Study on the early Hydration of Alkali-Activated Slag Cementing Materials

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.584-586.1465 ◽

2014 ◽

Vol 584-586 ◽

pp. 1465-1469 ◽

Cited By ~ 1

Author(s):

Jin Song Shi ◽

Xiao Hui Yuan ◽

Hui Guo Chen

Keyword(s):

Fly Ash ◽

Water Glass ◽

Coal Ash ◽

Hydration Heat ◽

Hydration Reaction ◽

Early Hydration ◽

Environment Temperature ◽

Activated Slag ◽

Cementing Material ◽

Alkali Activated

The early hydration of alkali-activator slag(AAS) cementing material is studied by changing the environment temperature, the proportion of slag and fly ash, water glass module, and dosage of sodium silicate. The results show that as the temperature raise, the hydration rate and hydration heat of the AAS cementing materials will remarkably accelerate. Joining coal ash in the pure slag cementing material can effectively slowdown its hydration reaction, and the hydration heat is also reduced.

Download Full-text