Reinforced concrete structural element with self-temperature sensingas an early warning system

Abstract

The invention relates to a reinforced concrete structural element with a self-temperature sensing that can detect instantaneous temperature change by using reinforcement elements as electrodes, determine the temperature of the element by examining the capacitance values of the concrete elements depending on the temperature change, and thus provide a way to monitor the temperature of the concrete elements and intervene when necessary.

Description

[0001] REINFORCED CONCRETE STRUCTURAL ELEMENT WITH SELF-TEMPERATURE SENSINGAS AN EARLY WARNING SYSTEM

[0002] Technical Field

[0003] The invention relates to a structural element that can be used for applications in critical structures, including bridges, tunnels, buildings and other civil engineering projects.

[0004] The invention particularly relates to a reinforced concrete structural element with a selftemperature sensing that can detect instantaneous temperature change by using reinforcement elements as electrodes, determine the temperature of the element by examining the capacitance values of the concrete elements depending on the temperature change, and thus provide a way to monitor the temperature of the concrete elements and intervene when necessary.

[0005] State of the Art

[0006] Today, it is important to regulate the temperatures in the highways, bridges and buildings in the construction industry and to keep the temperature under control. In order to achieve this, reinforced concrete structures must have self-temperature sensing feature. Structures with self-temperature sensing future provide an effective tool for detecting and mitigating potential problems such as frost and fire damage. In addition, in reinforced concrete structures with self-temperature sensing feature, timely intervention and maintenance are provided to the structure as of the beginning of the abnormal situation, and thus the long term integrity and safety of the built structure is ensured.

[0007] In the prior art, the temperature change of the concrete can be detected with some external sensors (https: / / www.tempcon.co.uk / ). Typically, these sensors are connected on the reinforcement and concrete is poured on it. From the beginning of the pouring process, immediate temperature monitoring is conducted. Although this method gives partially successful results, it also brings problems such as signal transmission instability, electrical power requirement, maintenance / repair requirement, and deterioration of structure stability. In addition to using an external sensor to determine concrete temperature, another method involves measuring the electrical resistances of composites containing conductive fillers to estimate the structure's temperature. Various studies have been carried out on the subject. For example, Wang et al. (2020) conducted research on temperature and humidity detection using electrical resistance. Electrical resistances of mortars containing carbon nanofibers measured at different temperatures (in the range of -30 °C - 100 °C) have been noted. Temperature sensing has been achieved by establishing a relationship between the temperature and electrical resistance of carbon nanofiber mortars. In this study, one of the limiting factors for the self-sensing mechanism is the difficulty in achieving homogeneous distribution of the nanofibers within the matrix.

[0008] In another study, Ji et al. (2016) aims to increase the thermoelectric properties of the material by adding nano metallic oxide particles such as ZnO and Fe2O3into cementitious composites. It has been emphasized that with the use of the said nanoparticles in cementitious composites, 10 times better performance is obtained compared to the thermoelectric properties provided by carbon fibers. The relationship between the temperature and electrical properties of cementitious composites has been established to enable temperature sensing. However, in this study, special equipment is needed for homogeneous distribution of nanoparticles. In addition, the high cost of nanomaterials is another disadvantage for the common use of these materials.

[0009] In addition, Demircioglu et al. (2019) investigated the effects of temperature and humidity on the electrical resistance and deformation sensitivity of smart concrete designed using brass fiber. Especially at high temperatures (above 150 °C), an increase of 613% in the electrical resistance of fibrous composites was detected as a result of incompatible deformation between brass fibers, cement paste and aggregates. For this reason, they suggested that the designed smart concrete can be used as a fire alarm sensor. However, Wen and Chung (1999) suggested that cementitious composites with self-temperature sensors can be designed by observing the temperature dependent behavior of the resistance values of carbon fiber cement pastes. As a result of the study, it was revealed by electrical measurements that it is possible to detect the temperature range of 1° C-45 °C by using carbon fibers together with silica fume in cement paste. Although this study is one of the pioneering studies, the temperature test range is quite low.

[0010] As a result of the research on the subject, the document numbered US10620062B2 has been encountered. The relevant document relates to self-sensing cement based compositions. It provides self-stress detection ability by establishing a relationship between the capacitance value of the existing concrete without technical additives and the varying stresses by applying load on it. Cement based composite is applied by using conductive plate as electrode. In addition, self-strain detection is provided by measuring the piezopermittivity value of the concrete; however, there is no selftemperature sensing by measuring the pyropermittivity value. The relevant document provides the determination of the stresses formed by measuring the capacitance value on the material without the need for any conductive additives. However, traditional reinforced concrete does not involve using steel reinforcement as electrodes to measure capacitance and resistance values that vary with temperature, thereby not enabling self-temperature sensing potential.

[0011] As a result, due to the said disadvantages and the insufficiency of the current solutions regarding the subject matter, a development is required to be made in the relevant technical field.

[0012] The Objective of the Invention

[0013] The object of the invention is to solve said disadvantages by being inspired from the current situations.

[0014] The main object of the invention is to put forward a reinforced concrete structural element with a self-temperature sensing that can detect instantaneous temperature change by using reinforcement elements as electrodes, determine the temperature of the element by examining the capacitance values of the concrete elements depending on the temperature change, and an early warning system which provides a way to monitor the temperature of the concrete elements and intervene when necessary.

[0015] Another object of the invention is to provide a reinforced concrete structural element that has a self-sensing structure in which it is used as a sensor and eliminates the need for an external sensor.

[0016] Another object of the invention is to eliminate the need for conductive filler with capacitance-based self-temperature sensing structure. In this respect, the structural element of the invention provides an advantage in terms of economy and can be applied with traditional concrete. In order to achieve said objects, the invention is a reinforced concrete structural element which has an early warning system with self-temperature sensing which is able to detect temperature change simultaneously by examining the capacitance values of concrete which change according to temperature change, characterized by comprising:

[0017] • Steel cage, which is one of the electrode pairs required for capacitance measurement, formed by the longitudinal cage reinforcement placed longitudinally in the concrete and the transverse cage reinforcement connected to said longitudinal cage reinforcement,

[0018] • A longitudinal single electrode positioned in the center of the reinforced concrete structure, which is another of the electrode pairs required for capacitance measurement, and

[0019] • A capacitance measurement device that detects the simultaneous capacitance value of the concrete by connecting to the longitudinal single electrode and the steel cage, which are electrode pairs, provides information about the temperature of the concrete elements by learning the detected capacitance value and provides early warning to the user in case of abnormal temperature changes.

[0020] The structural and characteristic features and all the advantages of the invention will be understood more clearly by means of the figures and the detailed description with reference to these figures provided below and therefore, the evaluation should be made by taking these figures and the detailed description into consideration.

[0021] Figures for a Better Understanding of the Invention

[0022] Figure 1 is general overview of the steel cage.

[0023] Figure 2 is overview of the reinforced concrete structure of the invention.

[0024] Figure 3 is cross-sectional view of the reinforced concrete structure.

[0025] Figure 4 is representative view of the test assembly. Descriptions of Component References

[0026] 1. Longitudinal cage reinforcement

[0027] 2. Transverse cage reinforcement

[0028] 3. Longitudinal single electrode

[0029] 4. Concrete

[0030] 5. Capacitance measurement device

[0031] 10. Steel cage

[0032] Detailed Description of the Invention

[0033] In this detailed description, the preferred embodiments of the self-temperature sensing reinforced concrete structural element of the invention are explained only for a better understanding of the subject.

[0034] The reinforced concrete structural element with self-temperature sensing of the invention which can detect the temperature change of concrete (4) elements by examining the capacitance values which change depending on the temperature change of concrete (4) elements fundamentally comprises a steel cage (10), a transverse cage reinforcement (2) and longitudinal cage reinforcement (1) which makes up the steel cage (10), longitudinal single electrode (3) and a capacitance measurement device (5).

[0035] The steel cage (10) shown in Figure 1 is one of the electrode pairs required for capacitance measurement. The steel cage comprises four longitudinal cage reinforcements (1) in the concrete structure and the spacer, that is, the transverse cage reinforcement (2) connected to this longitudinal cage reinforcement (1). The reinforced concrete structural element of the invention comprises a longitudinal single electrode (3), which is another of the electrode pairs required for capacitance measurement, positioned in the center of the reinforced concrete structure. Alongside this, it comprises a capacitance measurement device (5) that detects the simultaneous capacitance value of the concrete (4) by connecting to the longitudinal single electrode (3) and the steel cage, which are electrode pairs, provides information about the temperature of the concrete elements by learning the detected capacitance value, and provides early warning to the user in case of abnormal temperature changes. The reinforced concrete structure of the invention has been put forward in order to determine the temperature of the concrete element by examining the capacitance values of the concrete (4) elements with a steel cage (10), which is one of the electrode pairs, comprising a transverse cage reinforcement (2) and four longitudinal cage reinforcements (1), and the longitudinal single electrode (3). Here, the steel cage (10) is one of the electrode pairs, and the other electrode is the longitudinal single electrode (3). Capacitance measurement is performed between the two electrodes and heat exchange is detected. While the steel cage (10) is a standard component of a conventional reinforced concrete structure, with the invention, the longitudinal single electrode (3) is embedded in this structure.

[0036] The steel cage (10) and the longitudinal single electrode (3) forming the electrode pairs are connected to the Inductance capacitance measurement device (5), which is an Inductance-Capacitance-Resistance measurement device, and the simultaneous capacitance value of the concrete (4) is determined. The capacitance value varies depending on the material temperature, so learning the capacitance value provides important information about the temperature of the element. The reinforced concrete structural element of the invention also has an early warning system. Since the change in the temperature of the concrete means that the temperature of the environment also changes, if there is an abnormality in the temperature of the environment, this is understood by capacitance measurement and the user is warned. In this way, early warning is provided.

[0037] In the embodiment of the invention, the capacitance and resistance value of the reinforced concrete structural element (concrete reinforced with steel) changing with temperature is measured. Electrode elements forming the cage are used as electrodes. In addition, while self-strain detection is provided by measuring the piezopermittivity value of the concrete in the current art, self-temperature sensing is provided by measuring the pyropermittivity value with the subject of the invention. To explain this basic principle scientifically, the permittivity of cement based composite materials increases as the temperature increases. This increase is due to the fact that as the temperature rises, the ions move more. The effect of temperature on permittivity is called pyropermittivity and allows for capacitance based temperature sensing methods. REFERENCES

[0038] Demircilioglu, E., Teomete, E., Schlangen, E., Baeza, F. J. 2019. “Temperature and moisture effects on electrical resistance and strain sensitivity of smart concrete”, Construction and Building Materials, 224, 420-427. https: / / doi.orq / 10.1016ZJ.CONBUILDMAT.2019.07.091

[0039] Home | Concrete Sensors by Hilti. (n.d.). Retrieved July 24, 2023, from https: / / concretesensors.com / Ji, T., Zhang, X., Li, W. 2016. “Enhanced thermoelectric effect of cement composite by addition of metallic oxide nanopowders for energy harvesting in buildings”, Construction and Building Materials, 115, 576-581. https: / / doi.Org / 10.1016 / J.CONBUILDMAT.2016.04.035

[0040] Wang, H., Zhang, A., Zhang, L., Wang, Q., Yang, X. hong, Gao, X., Shi, F. 2020. “Electrical and piezoresistive properties of carbon nanofiber cement mortar under different temperatures and water contents”, Construction and Building Materials, 265, 120740. https: / / doi.Org / 10.1016 / J.CONBUILDMAT.2020.120740

[0041] Wen, S., Chung, D. D. L. 1999. “Carbon fiber-reinforced cement as a thermistor”, Cement and Concrete Research, 29(6), 961-965. https: / / doi.org / 10.1016 / S0008- 8846(99)00075-7

Claims

CLAIMS1. A reinforced concrete structural element which has self-temperature sensing with early warning system which can immediately detect the temperature change of concrete (4) elements by analyzing the capacitance values of concrete (4) elements depending on temperature change, characterized by comprising:• Steel cage (10), which is one of the electrode pairs required for capacitance measurement, formed by the longitudinal cage reinforcement (1) placed longitudinally in the concrete (4) and the transverse cage reinforcement (2) connected to said longitudinal cage reinforcement (1)• A longitudinal single electrode (3) positioned in the center of the reinforced concrete structure, which is another of the electrode pairs required for capacitance measurement, and• A capacitance measurement device (5) that detects the simultaneous capacitance value of the concrete (4) by connecting to the longitudinal single electrode (3) and the steel cage, which are electrode pairs, provides information about the temperature of the concrete elements by learning the detected capacitance value and provides early warning to the user in case of abnormal temperature changes.

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