Abstract
Concrete strength and factors affecting its development during early concrete curing are important research topics. Avoiding uncertain incidents during construction and in service life of structures requires an appropriate monitoring system. Therefore, numerous techniques are used to monitor the health of a structure. This paper presents a nondestructive testing technique for monitoring the strength development of concrete at early curing ages. Dispersed carbon nanotubes (CNTs) were used with cementitious materials and piezoelectric (PZT) material, a PZT ceramic, owing to their properties of intra electromechanical effects and sensitivity to measure the electromechanical impedance (EMI) signatures and relevant properties related to concrete strength, such as the elastic modulus, displacement, acceleration, strength, and loading effects. Concrete compressive strength, hydration temperature, mixture ratio, and variation in data obtained from the impedance signatures using fuzzy logic were utilized in the comparative result prediction method for concrete strength. These results were calculated using a fuzzy logic-based model considering the maturity method, universal testing machine (UTM) data, and analyzed EMI data. In the study, for data acquisition, a hybrid PZT–CNT sensor and a temperature sensor (Smart Rock) were embedded in the concrete to obtain the hydration temperature history to utilize the concrete maturity method and provide data on the EMI signatures. The dynamic changes in the medium caused during the phase in the concrete strengthening process were analyzed to predict the strength development process of concrete at early curing ages. Because different parameters are considered while calculating the concrete strength, which is related to its mechanical properties, the proposed novel method considers that changes in the boundary condition occurring in the concrete paste modify the resonant frequency response of the structure. Thus, relating and analyzing this feature can help predict the concrete strength. A comprehensive comparison of the results calculated using the proposed module, maturity method, and cylindrical specimens tested using the UTM proved that it is a cost-effective and fast technique to estimate concrete strength to ensure a safe construction of reinforced cement concrete infrastructures.
Highlights
To improve the construction quality and provide a safe environment for the construction of infrastructure, numerous techniques have been developed to monitor the health of a structure
To ensure the durability and proper strength gaining by structural members, it is important to determine the properties of concrete paste at various curing ages
We examine the combined use of smart materials of carbon nanotubes (CNTs) and piezoelectric (PZT) materials as a modified sensor, owing to their electrotechnical effects, to specify the early-age concrete strength based on the physical response properties of a concrete structure
Summary
To improve the construction quality and provide a safe environment for the construction of infrastructure, numerous techniques have been developed to monitor the health of a structure. For some large concrete structures, such as high-rise reinforced cement concrete buildings, bridges, and dams, continuous monitoring of their structural members or the overall structures at the early-construction and functional stages is highly challenging, technical, and time-consuming owing to their massive sizes. The conventional techniques, such as visual inspection by trained professionals, cannot provide interpretive health assessment and are unsuitable for such structures. We examine the combined use of smart materials of carbon nanotubes (CNTs) and piezoelectric (PZT) materials as a modified sensor, owing to their electrotechnical effects, to specify the early-age concrete strength based on the physical response properties of a concrete structure
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