Abstract
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.
Highlights
IntroductionIt is generally accepted that excessive thermal stress exceeds the tensile strength of concrete, which is the main reason for the cracking of early-stage mass concrete structure [1, 2]. e main reasons for the thermal stress of the early-stage mass concrete can be summarized as follows: the temperature of the concrete is unevenly distributed in space, and the local temperature gradient of the concrete is large; at the same time, the temperature and mechanical properties of the concrete change greatly in time, and the structure is subject to various constraints (foundation constraints, new and old concrete contact surface constraints, etc.) which will lead to large thermal stress [3, 4].e hydration heat released by the hydration reaction during concrete pouring is the most important reason for the uneven spatial and temporal distribution of temperature [5].e different heat release rate of hydration heat and the amount of heat released have a great influence on the spatial and temporal distribution of the concrete temperature field [6, 7]. erefore, the temperature control measures commonly used to control hydration heat include the use of lowcalorie cement, increasing the aggregate content when mixing, controlling the temperature of concrete pouring, and cooling by water [8, 9].in actual engineering project, it is difficult to adjust the concrete mix ratio
It is generally accepted that excessive thermal stress exceeds the tensile strength of concrete, which is the main reason for the cracking of early-stage mass concrete structure [1, 2]. e main reasons for the thermal stress of the early-stage mass concrete can be summarized as follows: the temperature of the concrete is unevenly distributed in space, and the local temperature gradient of the concrete is large; at the same time, the temperature and mechanical properties of the concrete change greatly in time, and the structure is subject to various constraints which will lead to large thermal stress [3, 4]
“reference concrete (BC)” and “inspected concrete (IC)” are fitted by the experimental data of adiabatic temperature rise; after that, the models of aqueduct, hydraulic tunnel lining (0.5 m), sluice floor and pier (1.2 m), and part of the gravity dam (18 m) were established. e thermodynamic parameters of “reference concrete (BC)” and “inspected concrete (IC)” obtained by experiment are used as calculation parameters to simulate the temperature field and stress field of different models. e thermodynamic parameters of the foundation and surrounding rock adopt the parameters of related actual engineering projects, and the concrete pouring time interval and pouring sequence are simulated according to the actual construction conditions
Summary
It is generally accepted that excessive thermal stress exceeds the tensile strength of concrete, which is the main reason for the cracking of early-stage mass concrete structure [1, 2]. e main reasons for the thermal stress of the early-stage mass concrete can be summarized as follows: the temperature of the concrete is unevenly distributed in space, and the local temperature gradient of the concrete is large; at the same time, the temperature and mechanical properties of the concrete change greatly in time, and the structure is subject to various constraints (foundation constraints, new and old concrete contact surface constraints, etc.) which will lead to large thermal stress [3, 4].e hydration heat released by the hydration reaction during concrete pouring is the most important reason for the uneven spatial and temporal distribution of temperature [5].e different heat release rate of hydration heat and the amount of heat released have a great influence on the spatial and temporal distribution of the concrete temperature field [6, 7]. erefore, the temperature control measures commonly used to control hydration heat include the use of lowcalorie cement, increasing the aggregate content when mixing, controlling the temperature of concrete pouring, and cooling by water [8, 9].in actual engineering project, it is difficult to adjust the concrete mix ratio. It is generally accepted that excessive thermal stress exceeds the tensile strength of concrete, which is the main reason for the cracking of early-stage mass concrete structure [1, 2]. E hydration heat released by the hydration reaction during concrete pouring is the most important reason for the uneven spatial and temporal distribution of temperature [5]. Erefore, the temperature control measures commonly used to control hydration heat include the use of lowcalorie cement, increasing the aggregate content when mixing, controlling the temperature of concrete pouring, and cooling by water [8, 9]. Advances in Civil Engineering projects, it is difficult to use temperature control measures such as aggregate precooling and ice mixing to control the temperature of concrete pouring due to economic factors. Used concrete admixtures include water-reducing agents, retarders, air-entraining agents, etc., among which water-reducing agents can reduce the use of water and reduce the heat released by the hydration reaction [16]
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