Determination of Early Age Mortar and Concrete Strength by Ultrasonic Wave Reflections

Abstract

The in-situ testing of early age concrete strength is crucial for determining the time of form removal from concrete elements, opening highways to traffic or applying of prestress to steel reinforcement. A nondestructive ultrasonic technique, which measures the reflection loss of ultrasonic transverse waves at a concrete-steel interface, is presented in this paper. The focus is to compare wave reflection measurements on mortar and concrete to strength. It is shown that the reflection loss is linearly related to the strength gain of mortar and concrete at early ages. The experiments have revealed a relationship between the homogeneity of the tested materials and the consistency of the reflection measurements. The repetition of simultaneous measurements of wave reflections and compressive strength on mortar results in similar strength-reflection loss relationships. Multiple measurements on the same concrete gave multiple strength-reflection loss relationships. The accuracy of the strength predictions made with the proposed method is discussed and compared to other nondestructive test methods.

Ultrasonic measurement of viscoelastic shear modulus development in hydrating cement paste

“…A one-sided experimental technique which monitors horizontally polarized shear (SH) wave reflected at normal incidence from an interface between a buffer material and cementitious material has been applied to monitor strength gain and elastic properties in hydrating materials [13,25,23,24,19,18,20]. In this technique, changes in the measured phase and amplitude of an ultrasonic pulse reflected from cementitious material were used to determine the evolution of shear modulus with time.…”

Review of Ultrasonic Wave Reflection Applied to Early-Age Concrete and Cementitious Materials

“…(1 − r 2 )4r sin ϕ ρ(1 + r 2 − 2r cos ϕ) 2 cos 2 θ 1 cos 2 θ 2 (10) where R = Z 1 1 − r 2 1 + r 2 − 2r cos ϕ cos θ 1 cos θ 2 (11)…”

“…Fused-quartz buffers has been used in laboratory applications when determining the elastic or viscoelastic material properties of the cementitious materials [16,17,32,33]. For field deployment and outdoor applications, steel buffer plates have been used [10,13,34]. Polymeric materials such as acrylic glass (also known as polymethyl methacrylate or PMMA under the brand names Plexiglas or Lucite ) and high-impact polystyrene, which have relatively low acoustic impedance, provide higher sensitivity to small changes in acoustic impedance of cemenitious materials, have been used at early stages of hydration, for measurements before and during setting [15,17,[19][20][21]35,36].…”

“…Pulser-receivers in combination with a broad-band transducers have been used for reflection measurements over a range of frequencies from 500 kHz to 5 MHz [10,14,15,31]. Generally, the wave frequency is defined by the testing set up employed, for example the size and material type of the buffer, or the test parameter to be measured, Relatively high frequencies can be used because the meaningful wave propagation occurs in the homogeneous solid buffer material and not in the cement based materials under test.…”

Fused empirical mode decomposition and wavelets for locating combined damage in a truss-type structure through vibration analysis

“…Some of these procedures are: the acoustic emission (Li et al, 2011), infrared thermography (Shih et al, 2000), ultrasound (Voigt et al, 2003), image processing (Nishikawa et al, 2012), eddy currents (Banks et al, 2002), and radiographs (Vossoughi et al, 2007); which are all used in assessing structural damage. However, the aforementioned methods possess several disadvantages; for instance, it is required that the location of the damage be known a priori, the section of the structure under inspection needs to be easily accessible and in several cases, the structures must be closed temporarily during its inspection (Curadelli et al, 2008).…”