Fuzzy Logic-Based and Nondestructive Concrete Strength Evaluation Using Modified Carbon Nanotubes as a Hybrid PZT–CNT Sensor

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.

Discrete Element Method Approach to Simulate Cracks in Four-Point Flexural Test

“…Concrete unused and scattered waste only becomes garbage that piles up and can contaminate the soil because of its cement content [11]. Therefore, numerical testing is one of the solutions for conducting concrete testing [12].…”

Self-powered flexible piezoelectric sensor based on PbZr0.52Ti0.48O3 nanofibers for impact force monitoring and rubber mat aging assessment

“…By adding amount of CNTs (1 wt.%) into 0.5Ba(Ti 0.8 Zr 0.2 ) O 3 -0.5(Ba 0.7 Ca 0.3 )TiO 3 /PDMS composite layer, Xing et al [24] obtained piezoelectric sensor with high sensitivity up to 5.189 mV mm −1 under a tiny deformation of less than 1%. The addition of CNTs is benefit for the delivery of the piezoelectric potential, highly stretchable and sensitivity to low frequency and small strains sensing [24][25][26]. On the other hand, the piezoelectric sensor can not only convert the strain signal into electrical signal, but also can harvest this electrical energy to achieve self-powered, which enables sensors to operate without external power [27,28], and even supply electric power for other low-power devices, which can be widely applied in traffic monitoring [29][30][31].…”