Nonlinear Impact Resonance Acoustic Spectroscopy Research Articles

Non-contact Non-linear Impact Resonance Acoustic Spectroscopy for thermal damage characterization on mortar samples

Abstract The high sensitivity of the nonlinear terms of the elastic response of materials to the incipient appearance of damage has led to the appearance of the Non-linear Elastic Wave Spectroscopy methods (NEWS). Particularly, the Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) technique detects changes in the resonance of a material (frequency, damping factor, etc.) as a function of the intensity of the impact. Traditionally, mechanical waves have been monitored using an external sensor in contact with the material. Currently, alternative technologies are capable of capturing mechanical waves without direct contact or with embedded sensors in the material itself from its manufacture. This helps the automation process or the continuous monitoring of the material. Mortar is the most used composite material in construction. In this work, thermal damage on mortar samples is characterized by NIRAS tests using different sensing techniques. Accelerometers have been used as the reference technique, while laser interferometer and Fiber Bragg Grating (FBG) have been used as non-contact and embedded sensor techniques respectively. Two levels of damage are presented: sound samples and 400ºC damage. The different techniques offer similar results, showing the capability of the proposed techniques (FBG and laser interferometry) to be an accurate alternative to traditional contact techniques for NIRAS testing.

Enhancing the durability performance of thermally damaged concrete with ground-granulated blast furnace slag and fly ash

This study investigates the effectiveness of ground-granulated blast furnace slag (GGBFS) and fly ash in improving the durability of concrete specimens subjected to thermal damage. Multiple techniques, including nonlinear impact resonance acoustic spectroscopy (NIRAS), compressive strength, X-ray diffraction, and thermogravimetry, are employed to capture the physical and chemical phenomena resulting from a temperature elevation of 200, 400, 600, and 800 °C. The experimental results demonstrated that replacing cement with fly ash (20 wt%) and GGBFS (40 wt%) yields significant mitigation of microcracking development, highlighting their potential as agents for enhancing concrete durability under high-temperature exposure. Notably, the hysteresis nonlinearity parameter (α) measured using NIRAS exhibits a high sensitivity for detecting the transition from micro to macroscale defects, and the trend of α sufficiently coincides with the results of the mineralogical analyses, confirming the evaporation of free water, dehydration of calcium silicate hydrate (C-S-H), and decomposition of calcium hydroxide (CH).

Mitigating self-desiccation of cement composites via cellulose microfibers: Evidence of the microscopic behavior

Water-saturated cellulose microfibers (CMFs) incorporated into fresh cement composites can mitigate microcracking induced by self-desiccation during drying. This study utilized a nonlinear impact resonance acoustic spectroscopy (NIRAS) technique to elucidate the mechanism underlying the CMF-driven mitigation of self-desiccation. The hysteresis nonlinearity parameter (α) from the NIRAS was used to quantify the microstructural changes in three different mixtures (0 0.3 and 1% dosages of CMFs). Computed tomography (CT) compression tests and periodic measurements of mass and resonance frequency were performed to obtain more insights into mitigating self-desiccation. Supported by the collected data the results show a remarkable reduction in α over time confirming high sensitivity of α to the microstructural change. Furthermore the trend of α was consistent with the pore size distribution estimated by the CT test which provides quantitative evidence to support the mitigation of self-desiccation promoted by CMFs. We envision that these findings can be used as guidelines for enhancing the durability of cement composites facilitated by CMFs.

Assessment of internal curing of cellulose microfibers-incorporated cement composites using destructive and nondestructive methods

Water-saturated cellulose microfibers (CMFs) incorporated into fresh cement composites can facilitate the internal curing, holding a potential for mitigating intrinsic material defects such as microcracks, interfacial transition zones (ITZs), and pores that raise the material nonlinearity. To elucidate the contribution of water supply from CMFs to internal curing process, this study utilizes the nonlinear impact resonance acoustic spectroscopy (NIRAS) technique. Hysteresis acoustic nonlinearity parameter (α) and linear resonance frequency are measured from the NIRAS tests and used to nondestructively quantify the microstructural changes induced by different degrees of internal curing in three different samples (with 0, 0.3, and 1% dosage of CMFs). To get more insight into this phenomenon, other properties including porosity, internal relative humidity (IRH), autogenous shrinkage, compressive strength, and ultrasonic wave velocity are also measured. Evidenced by all measured data, our results confirm that α shows a high sensitivity to the extent of microstructural change in cellulose microfibers-incorporated cement composites, which solely enables capturing time-dependent microstructural changes and thus the discrimination between internal curing effect and development of intrinsic material defects (or material nonlinearity). We believe that this study can lay the foundation for enhancing the durability performance of cement composites via CMFs.

Effects of slow dynamics and conditioning on non-linear hysteretic material assessment using impact resonance acoustic spectroscopy

The microstructural features of heterogeneous and porous materials give rise to unique non-linear dynamic behaviour. The purpose of this work is to investigate the dynamic response of thermally damaged concrete specimens measured by two different techniques: Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) and new Flipped Accumulative Non-linear Single Impact Acoustic Spectroscopy (FANSIRAS). Specimens were characterised in two different dynamic condition states of the material: relaxed and conditioned. The specimen’s relaxed state indicates that no previous dynamic excitation event ocurred. The conditioned state denotes that the specimen has been dynamically tested before. The NIRAS results show that the non-linear material parameters, αf and αQ, are affected by their previous dynamic history (its conditioning). The recently proposed algorithm, FANSIRAS, extracts from a single resonant signal equivalent results to NIRAS when the specimen is conditioned. In this situation, both parameters αf and αQ were equivalent. The results suggest that new NDT parameters based on non-linear hysteretic parameters can quantify the damage level of thermally treated mortar specimens.

Nonlinear Acoustic Spectroscopy and Frequency Sweep Ultrasonics: Case on Thermal Damage Assessment in Mortar

An exhaustive study on thermal damage of Portland cement-based materials is addressed. Damage carried out at different temperatures on concrete between 40 and $$525\,^{\circ }\hbox {C}$$ were assessed by means of microstructural, physical and nondestructive tests. Microstructural analysis (thermogravimetry and scanning electron microscopy) showed the principal changes of the Portland cement hydrated products for the different analysed temperatures. Compressive and flexural strengths remained constant or even increased at a low heating temperature range, while the mass loss increases. Dilatometry analysis revealed important information about deformation incompatibilities between the paste and the aggregate. These results have been correlated with nondestructive tests: nonlinear impact resonance acoustic spectroscopy (NIRAS) and ultrasonic measures. The dynamic modulus and ultrasonic pulse velocity have closely predicted the linear stiffness decay of the specimens. However, hysteretic parameter from NIRAS analysis exhibited a different trend from stiffness-related parameters, keeping constant until $$250\,^{\circ }\hbox {C}$$ and suffering a huge increasing for 400 and $$525\,^{\circ }\hbox {C}$$ . Ultrasonic attenuation computed with a broadband ultrasonic signal (chirp) revealed interesting information about scattering components inside the material, and is sensitive to interfacial transition zone between aggregate and paste in a large range of frequencies. The correlation between microstructural, mechanical and nondestructive techniques were carried out successfully. Nonlinear vibration and ultrasonic attenuation are non-conventional parameters that gave specific information about a complex damage process, such as a thermal attack in highly heterogeneous materials (e.g. Portland cement composites).

Flipped Accumulative Non-Linear Single Impact Resonance Acoustic Spectroscopy (FANSIRAS): A novel feature extraction algorithm for global damage assessment

High amplitude non-linear acoustic methods have shown great potential for the identification of micro-damage in inhomogeneous materials such as concrete. Usually, these methods evaluate non-linearity parameters related to the hysteretic behaviour from the dependence of the shifts in both frequency and damping on the amplitude of the strain. A deep understanding of the reverberation phenomena has been obtained in order to introduce a novel signal processing approach called FANSIRAS (Flipped Accumulative Non-linear Single Impact Resonance Acoustic Spectroscopy). Traditional acoustic spectroscopy techniques, NIRAS (Non-linear Impact Resonance Acoustic Spectroscopy) and NSIRAS (Non-linear Single Impact Acoustic Spectroscopy), have been analyzed and compared with the brand new approach when providing quantitative information related to the degree of micro-cracking in thermal damaged concrete based materials. The new resonance-based algorithm demonstrates that the non-linear non-classical parameters can be determined through a single resonance frequency measurement, obtaining the expected sensitivity to internal damage. Its simplicity and robustness may be important in industrial applications.

Insights into delayed ettringite formation damage through acoustic nonlinearity

A nonlinear acoustic approach for the detection and quantification of damage in mortars affected by delayed ettringite formation (DEF) is used to provide insights into the degradation mechanism at the microscale and its correlation with bulk expansion. The nonlinear acoustic technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS) successfully differentiates among mortars experiencing various amounts of expansion and microstructurally-evident distress due to DEF. Results indicate that mortars are damaged both during the early-age high-temperature curing and subsequent 23°C-limewater curing. However, the time of initiation of expansion occurs earlier for samples showing higher damage level (as measured by average nonlinearity parameter) at the end of high-temperature curing. During the exposure period, the ratio of absolute maximum to the initial average nonlinearity parameter of DEF-affected mortars varies from 3 to 30, indicating that the DEF damage can increase more than an order of magnitude greater than that experienced during the high-temperature curing.

Assessment of sulfate attack and freeze–thaw cycle damage of cement-based materials by a nonlinear acoustic technique

In this work, a nondestructive evaluation technique (NDE) based on nonlinear impact resonance acoustic spectroscopy (NIRAS) is applied to the assessment of mortar and concrete damage caused by the sulfate attack and freeze–thaw cycles. The nonlinear parameter is defined as the relative shift of resonance frequency against the vibration acceleration magnitude and compared with traditional parameter (i.e. linear resonance frequency) for damage characterization. The nonlinear parameter increases with the development of sulfate attack damage in mortar samples and presents a positive correlation with the expansion results in the standard accelerated experiments, indicating the feasibility of NIRAS technique in assessment of sulfate attack damage. The experimental results also validate the sensitivity of NIRAS technique to sulfate attack damage. The nonlinear parameter increases about 140 % and 3700 % after 2 and 3 months of sulfate solution exposure, while the linear resonance frequency changes about 5 % and 24 %, respectively. On the other hand, the nonlinear parameter shows a monotonically increasing trend for concrete samples subjected to increased freeze–thaw cycles and presents an appreciable distinction for samples having different capillary water. The nonlinear parameter of concrete samples with 0.55 w/c ratio is about 10 times that of concrete samples with 0.45 w/c ratio after 150 freeze–thaw cycles. The experimental results in this paper demonstrate that the developed NIRAS technique not only can be used a good NDE method for damage assessment of cement-based materials caused by durability problem such as sulfate attack and freeze–thaw cycles, but also has the potential to reveal the variation of microstructural characteristics of materials such as the microcracking development and moisture content change.

Comparison of various methods of nonlinear signatures extraction

Nonlinear Acoustic NDE (NA NDE) methods are very sensitive to defect presence and currently number on publications on this matter exceed several thousand. Despite intensive research of NA NDE, these methods are still do not widely used in practice and the goal of this presentation is to give review of various methods of nonlinear signatures extraction and to show advantages on some of them in the comparison with the others. The major part of the NA NDE was applied for characterization the tested part as whole. These methods include: High Harmonic Generation, Nonlinear Resonant Ultrasound Spectroscopy (NRUS), Amplitude Dependent Internal Friction, Nonlinear Wave Modulation Spectroscopy (NWMS) or Vibro Acoustic Modulation (VAM), Slow Dynamics Diagnostics (SDD), Nonlinear Reverberation Spectroscopy (NRS) or Nonlinear Impact Resonance Acoustic Spectroscopy (NRAS), Nonlinear Coda Wave Interferometry, Bi Spectral and High Order Statistic Analysis, Subharmonic and Ultraharmonic Methods. The methods that can provide nonlinear imaging and damage localization include: Nonlinear Time Reversal Acoustics (NTRA) or TR NEWS, Nonlinear Harmonic Imaging, Nonlinear Acoustic Tomography, Pulse Modification of Vibro Acoustic Modulation (VAM), Nonlinear Guided Wave Imaging and Tomography, Subharmonic and Ultraharmonic imaging, Nonlinear Structural Intensity.

Multimodal analysis of GRC ageing process using nonlinear impact resonance acoustic spectroscopy

Glass fibre Reinforced Cement (GRC) is a composite material composed of Portland cement mortar with low w/c (water/cement) ratio and high proportion of glass fibres. This material suffers from the ageing process by losing its strength with time because of its exposure to severe weather conditions. Ageing process damages the fibre surface and decreases the mechanical properties of the structural components made of this material. It reduces the elastic modulus and toughness of GRC. Fracture toughness is traditionally measured by four point bending tests. In a previous study by the authors it was observed that ageing related deterioration or damage of GRC could be monitored by Non Destructive Testing (NDT) techniques such as Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) and other ultrasonic techniques. The scope of this paper is to corroborate previous investigations and offer early damage detection capability by generating more experimental data points by optimizing location of the point of strike and thus generating more resonance vibration modes in NIRAS tests.

Preliminary study on short-term sulphate attack evaluation by non-linear impact resonance acoustic spectroscopy technique

The scope of this paper is to study the sulphate attack on concrete with new testing methods based on vibrational spectroscopy with mechanical waves. These are based on Non-linear Impact Resonance Acoustic Spectroscopy (NIRAS) that allows detecting the frequency shift of its resonant modes. Both, signal quality factor and alpha, are measured to monitor the increase of the non-linearity of the material due to the stiffness change on the matrix after being attacked. Different Portland cement matrices were assessed and results between vibrational tests and the traditional expansion ASTM method were compared. Two types of cement with different C3A content were tested for external sulphate attack and one cement with high C3A content with different amount of addition of SO3 on the original mix was tested for internal attack. NIRAS was suitable for monitoring external sulphate attack process. A microstructual analysis was carried out with thermogravimetry (TG), scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques in order to detect harmful products on damaged series.

Experimental study of effects of water–cement ratio and curing time on nonlinear resonance of concrete

Experimental techniques based on the theory of nonlinear acoustic resonance have been proved highly sensitive to the development of damage in concrete, particularly during the early age. As a multiphase composite material, the microstructure of concrete has a significant influence on damage development of concrete when subjected to external loading. Hence, it is important to understand the effect of main parameters associated with material microstructure such as water–cement (w/c) ratio and curing period on the nonlinear resonance response of concrete. In this research, theoretical background is first introduced for the implemented nonlinear impact resonance acoustic spectroscopy (NIRAS) technique, in which a parameter representing material nonlinearity is designated as the overall indicator for discontinuous material features of concrete samples. Applying the NIRAS technique, the nonlinearity parameter is analyzed for two sets of concrete samples mixed with different w/c ratios and cured for 7 and 28 days, respectively. The results show that under the increased loading, the longer curing time generally reduces the nonlinear response of concrete because the late filling effect of hydrated products in voids of interfacial transition zone could limit the development of microcracks. The higher w/c ratio will accelerate the nonlinear response of concrete due to the interconnection effect of material porosity on the propagation of microcracks. It is also noteworthy that the nonlinear response of samples in intact state corresponding to a lower w/c ratio is, however, enhanced. This effect is explained by the fact that less capillary water existing in the samples mixed with a lower w/c ratio work as lubricating fluid in voids to mitigate the opening–closing motion of initial material defects.

Assessment of alkali–silica reaction damage through quantification of concrete nonlinearity

A newly developed nondestructive evaluation technique, Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS), is applied to concrete specimens in an ongoing assessment of aggregate alkali reactivity during standard concrete prism testing. NIRAS measures the nonlinearity in a specimen caused by the inception and growth of microcracks throughout the sample and debonding at the aggregate/cement interface. NIRAS is used to exploit the nonlinear effect of excitation amplitude dependent resonance frequency changes, which are related to nonlinearity measurements of concrete samples cast with aggregates of varying reactivity. To relate microstructural changes to changes in nonlinearity and expansion, sample characterization is performed with uranyl-acetate staining. The results demonstrate the utility of NIRAS for not only assessing the potential for ASR under standardized test conditions, but for more general damage characterization in concrete and assessment of “job mixtures.” NIRAS can distinguish reactive from nonreactive aggregates without ambiguity, as supported by sample characterization results.

Characterization of ASR damage in concrete using nonlinear impact resonance acoustic spectroscopy technique

This research reports on a successful application of the nonlinear impact resonance acoustic spectroscopy (NIRAS) technique for the characterization of progressive damage in standard concrete specimens. Damage in the specimens is introduced, following ASTM C 1293 testing procedures, through the deleterious alkali–silica reaction (ASR), which leads to the formation of a gel-like reaction product, microcracks, and interfacial debonding between cement and aggregate phases. The microcracks and debonded interfaces act to increase the nonlinearity of concrete. The response of the specimen to impact loading is analyzed to obtain a nonlinearity parameter, which is used as a measure of damage. Measurements are performed on concrete prisms undergoing the ASTM C 1293 expansion test; three aggregates with varying reactivity are examined. The results from the expansion test are compared with those from the NIRAS measurements. For potentially reactive aggregate, the NIRAS technique offers a more definitive assessment of the damage state of the specimen and can be used to distinguish marginally reactive aggregates. The NIRAS results not only demonstrate a clear distinction between nonreactive and reactive aggregates using the nonlinearity parameter, but also the capability to quantitatively track ASR-induced damage in concrete, potentially forming the foundation for field assessment and monitoring.

Rapid evaluation of alkali–silica reactivity of aggregates using a nonlinear resonance spectroscopy technique

A new nonlinear acoustic technique — Nonlinear Impact Resonance Acoustic Spectroscopy (NIRAS) — is developed and used to characterize the alkali-reactivity of different aggregates. Cementitious materials such as mortar and concrete exhibit a hysteretic and nonlinear elastic behavior in their constitutive relations. This hysteretic nonlinearity is associated with interfacial debonding between the different constituents, and it changes with the progress of damage such as that induced by the alkali–silica reaction (ASR). One of the consequences of the hysteretic nonlinear property of these materials is the decrease in resonance frequencies, with increased excitation amplitude. This shift in the resonance frequency as a function of the material nonlinearity parameter can be used to directly characterize the damage state of the material. This research tracks the variation of the nonlinearity parameter during a standard accelerated mortar bar test (AMBT) to assess the potential for alkali-reactivity of aggregates. The results show that the NIRAS technique is more sensitive than conventional linear acoustic methods and is capable of accurately characterizing the reactivity of the aggregates examined. Furthermore, the results show advantages over standard expansion measurements for differentiating various aggregates having similar levels of reactivity, particularly at early test ages. These changes in the nonlinearity parameter are benchmarked against results from a petrographic analysis. Thus, the proposed NIRAS is a promising technique for the rapid identification of alkali-reactive aggregates.