Concrete early-age strength monitoring using embedded piezoelectric transducers

Abstract

At early ages of concrete structures, strength monitoring is important to determine the structures' readiness for service. Piezoelectric-based strength monitoring methods provide an innovative experimental approach to conduct concrete strength monitoring at early ages. In this paper, piezoelectric transducers in the form of 'smart aggregates' are embedded into the concrete specimen during casting. Piezoceramic materials can be used as actuators to generate high frequency vibrating waves, which propagate within concrete structures; meanwhile, they can also be used as sensors to detect the waves. The smart aggregate is a one cubic inch, precast concrete block with a wired, embedded PZT (lead zirconate titanate, a type of piezoceramic) patch. The strength development of concrete structures is monitored by observing the development of harmonic response amplitude from the embedded piezoelectric sensor at early ages. From experimental results, the amplitude of the harmonic response decreases with increasing concrete strength. The concrete strength increases at a fast rate during the first few days and at a decreasing rate after the first week. Concordantly, the amplitude of the harmonic response from the piezoelectric sensor drops rapidly for the first week and continues to drop slowly as hydration proceeds, matching the development of the concrete strength at early ages. Concrete is heterogeneous and anisotropic, which makes it difficult to analyze mathematically. Fuzzy logic has the advantage of conducting analysis without requiring a mathematical model. In this paper, a fuzzy logic system is trained to correlate the harmonic amplitude with the concrete strength based on the experimental data. The experimental results show that the concrete strength estimated by the trained fuzzy correlation system matches the experimental strength data. The proposed piezoelectric-based monitoring method has the potential to be applied to strength monitoring of concrete structures at early ages.

Real-Time Strength Monitoring for Concrete Structures Using EMI Technique Incorporating with Fuzzy Logic

“…Thus, PZT materials can be used and embedded in concrete to induce and detect wave propagation and vibrations [5,17,18,23]. Through different approaches, the piezoelectric sensors can use to estimate the strength of concrete.…”

“…Because concrete is a heterogeneous material, consisting of a mixture of water, cement, fine aggregates, coarse aggregates, fiber/steel, and different other admixtures, it is sensitive to the curing process that is used to gain the design strength [3]. Thus, concrete needs to be monitored precisely from right after it is poured until the 28th day to determine whether it has achieved the appropriate design strength [4,5]. Wide range of novel technologies have been adopted to construct concrete structures to decrease costs and increase safety in NPPs and other construction industry.…”

“…NDT (non-destructive testing) methods are usually considered to be cost effective and time-saving approaches to estimating the state of structures [7][8][9]. NDT methods for concrete include the rebound/Schmidt hammer test, ultrasonic wave propagation, and techniques that use PZT (piezoelectric) materials [5,[10][11][12][13][14]. Due to the accuracy of its result, the strength estimation of concrete using EMI has been widely studied [13][14][15][16][17][18][19].…”

Monitoring of the ultrasonicP-wave velocity in early-age concrete using Smart Aggregates

“…While they are used primarily for applications involving thin metallic or composite structures, they can also be used in concrete where they are either surface mounted or embedded. A successful implementation of embedded transducers called "Smart Aggregates" (SMAG) has been recently developed at the University of Houston [4,5] and used mainly to monitor the compressive strength and crack evolution in concrete structures. The SMAGs consists in a flat piezoelectric PZT patch (of approximate size 12mm x 12 mm x 0.2 mm) which is wrapped in a waterproof coating and embedded in a small cube or cylinder made of mortar ( Figure 2).…”

Nondestructive Concrete Strength Estimation based on Electro-Mechanical Impedance with Artificial Neural Network

“…The properties of ultrasonic vibration or wave propagation, such as velocity or attenuation, are affected by the change of physical properties. Thus, the strength development can be monitored, by tracking the change of ultrasonic signals (Gu et al 2006;Jonsson and Olek 2004;Oh et al 2016;Shin et al 2008;Kim et al 2013Kim et al , 2015Tawie et al 2010). Furthermore, a range of methods based on the acoustical, electrical, magnetic, optical, radiographic, and other mechanical properties of concrete have been studied (ACI Committee 228 2003;Lamond and Pielert 2006).…”