Avaliação da rigidez do concreto com smartphones: Validação de um método não destrutivo por vibração transversal

Abstract

ABSTRACT The accurate determination of the modulus of elasticity (E_c) of concrete is crucial for structural engineering, however standardized testing methods are dispendious and restricted to laboratory environments. This paper proposes and validates a non-destructive and low-cost methodology for the assessment of the dynamic transverse modulus of elasticity (E_(cd,vt)). of a reinforced concrete beam, utilizing a smartphone's accelerometer. The method consists of obtaining the beam's fundamental natural frequency by analyzing its free vibration response, employing the Fast Fourier Transform (FFT), and subsequently calculating the (E_(cd,vt)). For validation, the results were compared with the static modulus of elasticity (E_ce), determined from uniaxial compression tests on cylindrical specimens at ages of 3, 7, 14, and 28 days. Although a divergence in the absolute magnitudes of the moduli was noted, attributed to the different stress states of the tests, the linear regression analysis revealed a statistically robust correlation between the two methods, with a coefficient of determination (R²) of 0,997. This high degree of correlation allowed for the development of an empirical calibration equation and validates the proposed approach as a practical and reliable tool for the expeditious characterization of concrete stiffness. The methodology demonstrates the potential of mobile devices for the quality control of concrete on construction sites, aligning academic research with the needs of the construction industry.