Cracked Specimens Research Articles

Analysis of peel and shear strains in cracked lap shear specimens subjected to fatigue loading using digital image correlation

Adhesive bonding presents many advantages, such as efficient manufacturing and improved structural performance [1]. However, in structures subjected to fatigue, cracks might initiate and propagate in joints, leading to in-service failure [2]. Most adhesively bonded joints are subjected to combination of peel and shear loads, so mixed I+II mode loading conditions are present [3]. In this work, Cracked Lap Shear specimens, which feature mixed I+II mode loading conditions, were tested under fatigue loading. During tests, crack growth was monitored using Visual Testing and Digital Image Correlation. With Digital Image Correlation, opening and sliding displacements in the bondline were extracted from the substrates’ displacement fields and compared against a Finite Element Model, revealing a highly strained process zone ahead of the crack tip. Results highlight the usefulness of DIC in capturing the deformation behaviour of adhesive joints under mixed mode loading conditions.

The investigation of shrinkage cracking of paste and mortar based on the eccentric ring test and multiphysics simulation

The eccentric ring test presents a novel approach to evaluating the occurrence of shrinkage cracking in cementitious materials. The eccentric ring test has been confirmed to induce cracks on the thin sides of the specimen. However, the underlying mechanism behind this cracking phenomenon remains inadequately explored. In this study, the eccentric ring test is used to examine cement paste with different water-cement (w/c) ratios and mortar with varying aggregate volume fractions. The examination focuses on the influence of surface sealing and immersion curing on shrinkage cracking. The integrated shrinkage model, which is applicable to both autogenous shrinkage and drying shrinkage, is introduced to simulate the shrinkage of cementitious materials. The shrinkage cracking of eccentric specimens is further investigated through a multiphysics coupling analysis that considers shrinkage, humidity field, and stress field. The simulation results show that the humidity decreases more rapidly on the thinner sides during the shrinkage of the eccentric ring. The circumferential stress in the specimen is much greater than the radial stress. Additionally, the tensile stress in the circumferential direction exceeds 4 MPa on the outer ring. As the drying time increases, the circumferential tensile stress on the thin sides of the eccentric ring develops more rapidly, resulting in cracking on the thin side. The eccentric ring test is practicable in ordinary concrete and high-strength concrete, and the simulation is of significance in examining the cracking risk of concrete pipes and some thin wall components since these components are sensitive to the shrinkage cracking.

Prefabricated Ferrocement Jacket for Repairing and Strengthening Axially Loaded Square Sub-Standard Concrete Stub Columns

For decades, ferrocement has been used to repair, strengthen, and even build structural components because it is a long-lasting and reasonably priced material. However, onsite ferrocement jacketing is time-consuming and labour-intensive. Alternatively, prefabricated ferrocement jacket installation eliminates these shortcomings. Therefore, this study utilises wearable prefabricated ferrocement jackets to repair and strengthen axially loaded sub-standard low-strength concrete elements. In order to repair cracked specimens and strengthen existing intact specimens, two types of wearable prefabricated jackets are proposed, ‘L’ shape and ‘U’ shape. Besides a control specimen, two preloaded and two unloaded square concrete specimens were utilised to repair and strengthen using the Prefabricated Ferrocement Jacketing system. The test results and crack patterns show that all the jacketed specimens performed better than the control specimens in terms of load-bearing capacity, ultimate axial and lateral deflection, and ductility. In terms of load-bearing capacity, the unloaded strengthened specimens showed significant results consistently. Based on the results, the proposed solutions were found to be effective in solving the problem of typical square ferrocement jackets.

Characterization of crack-free AA-7075 fabricated by laser powder bed fusion with addition of Zr50.7Cu28Al12.3Ni9 metallic glass

The inclusion of 2 wt% Zr50.7Cu28Al12.3Ni9 metallic glass (MG) powders successfully eliminated the hot cracks in AA-7075 specimens fabricated using laser powder bed fusion (LPBF). The microstructure analysis revealed a significant enhancement in grain refinement within the AA-7075/MG specimen as a result of the formation of Al3Zr precipitates. The average grain size reduced from 9.26 μm to 1.6 μm, and the previously coarser columnar grains transformed into finer equiaxed grains with random orientation. Moreover, the AA-7075/MG specimen demonstrated a noteworthy microhardness exceeding 160 HV. With an elongation of about 7.2%, the highest ultimate tensile stress and yield strength are 488.7 MPa and 460.8 MPa, respectively.

Experimental investigation of crack evolution in expansive soil-rubber mixture (ESR) under freeze-thaw cycles

Expansive soil in the seasonally frozen region undergoes a long-term cycle of freezing and thawing. The complex and diverse crack shape that results from repeated swell-shrink distortion of expansive soil poses a serious threat to engineering. Expansive soil-rubber mixture (ESR) improves swelling-shrinkage characteristic and the mechanical properties of expansive soil. Using ESR and expansive soil as test objects, we investigate the effect of rubber powder on the characteristics of expansive soil crack evolution under freeze-thaw cycles. Image processing technologies are used to provide quantitative analysis of the crack images obtained from the test. The results showed that after freeze-thaw cycles, the cracks in the expansive soil specimens had a grid-like and bifurcated pattern with 90° and 120° bifurcations, but the cracks in the ESR specimens had a jagged and dendritic distribution. Comparing ESR and expansive soils, adding 5% rubber powder effectively lowers the complexity of crack evolution and surface crack ratios. The interlocking action of the rubber particles resists the freezing tension on the soil particles, effectively restricting the deformation and opening of the soil particles, decreasing water evaporation and the formation of cracks. In addition, the fractal dimension of ESR and the surface crack ratios satisfy the unique functional relationship under freeze-thaw cycling conditions. Consequently, adding 5% rubber powder to expansive soils might be a realistic and creative strategy for minimizing crack formation in the soil in the seasonal frozen region.

Thermomechanical modeling and experimental study of a multi-layer cast iron repair welding for weld-induced crack prediction

Large-scale components such as hubs in wind turbines are often made of cast iron to minimize the production costs. One of the common challenges in the casting process of such large-scale components is manufacturing defects. However, repair welding will induce residual stress which can initiate cracks in the repaired structure, especially since cast iron is not as tough as steel. The current study addresses developing a thermo-mechanical model of the cast iron repair weld validated with experiments to predict thermal and residual stresses and to identify critical locations for crack initiation. A thermo-mechanical weld model is developed, and the predicted temperature and residual stress distribution are validated against experimental data. Two repair weld experiments, one manual and one automated are carried out and are simulated using the developed thermo-mechanical model. The regions with maximum principal residual stresses are calculated by the thermo-mechanical model and the maximum principal stress method is used to predict the location and direction of the developed cracks in the repair weld. A comparison with the repair weld experiments shows good correlation with the observed cracks in the welded specimens. The outcome of this research provides a basis for repair weld optimization of large-scale cast iron components in order to reduce the carbon footprint caused by their reproduction.

Damage evolution and constitutive model of the rock masses with non-penetrating cracks under repeated impact loading.

A large number of cracks exist in natural rock masses, which significantly affects the stability of surrounding rocks in engineering under impact loading. Repeated impact tests by Split Hopkinson Pressure Bar are performed on non-penetrating cracked granite specimens with different prefabricated-crack inclination angles (0, 30, 45, 60, and 90°). The damage evolution law of cracked rock under repeated impact loading is investigated. Macroscopic damage variables considering geometric and mechanical parameters of cracks are proposed. Further, a constitutive model for the impact loading test is developed based on the coupling damage. It has been found that, the impact resistance of fractured rock first decreases and then increases with the increased prefabricated-crack inclination angle. The impact resistance for specimens with an inclination angle of 45° is the minimum. Theoretical results from the developed model agree with the experimental data. The model could well describe the progressive damage characteristics of cracked rock masses.

Evolution of tensile strength and cracking in granite containing prefabricated holes under high temperature and loading rate

For present applications in deep significant rock engineering, including underground repositories of high-level nuclear waste, an exhaustive comprehension of the impacts of high temperature and loading rate effects on the mechanical characteristics of granite emerges as an imperative necessity. Based on the Brazilian splitting test, Brazilian disc specimens with prefabricated holes were meticulously employed to guarantee the occurrence of radial compression failure. Combining microscopic experiments such as scanning electron microscopy and X-ray diffraction, the indirect tensile strength and damage mechanism of granite from the Yueyang area under the action of different temperatures and loading rates were thoroughly investigated. Furthermore, a nonlinear fitting equation between the two factors and tensile strength is suggested. At the same time, a simplified surface crack density based on pixel processing was defined. This allowed for a comparative assessment of how variations in temperature and loading rates induce varying degrees of macroscopic crack development and damage to the specimens. The findings suggest a direct proportionality between the tensile strength of granite and the loading rate, while an inverse proportionality is observed concerning temperature above 400 °C. However, a transient "gain effect" phenomenon manifests at temperatures below 400 °C. However, the impact of temperature on tensile strength is significantly greater than that of the loading rate, exhibiting a difference of approximately 8.7 times. Furthermore, the temperature is more prone to lead to the occurrence of secondary tensile cracks in specimens. The results of this research provide valuable guidance for ensuring the security of deep major rock engineering during construction.

Influence of Layer Thickness Ratio on the Mechanical and Failure Properties of Soft-Hard Interbedded Rock-like Material

To figure out the influence of soft-hard layer thickness ratio on specimens' mechanical properties evolution and microcracking mechanism, combined with digital image correlation technology and acoustic emission facility, uniaxial compression tests were conducted on soft-hard interbedded rock-like materials considering seven bedding dip angles and two soft-hard layer thickness ratios. The results are as follows: 1) The failure mode and failure pattern of layered rock masses are mainly determined by the bedding dip angle α and are less related to the soft-hard thickness ratio. With the increase of dip angle, the failure strength curve of the specimen is approximately U-shaped, and the soft-hard layer thickness ratio affects the U-shaped. The decrease in soft-hard layer thickness ratio will reduce the uniaxial compressive strength of specimens with low dip angles (α≦30°), cause differences in the evolution path of local strain fields of layered rock masses and reduce the horizontal displacement of the main crack. 2) The increase of the proportion of soft layer in the soft-hard layer thickness ratio will reduce the proportion of tensile cracks in the tensile failure specimens and shear cracks in the shear failure specimens, complicating the process of cracks of the layer rock mass. 3) Increasing the proportion of soft layers in the soft-hard layers thickness ratio promotes the generation of secondary cracks in layered rock masses and further reduces the integrity of specimens. Finally, through the findings in this paper, it can provide a reference for analyzing the crack propagation behavior of layered rock.

Fracture parameters analysis of compact tension specimens with deflected fatigue cracks: ZK60 magnesium alloy

Precise monitoring of crack growth and a comprehensive understanding of crack propagation rate are crucial for the evaluation of the structural integrity of magnesium alloys with defects. Different crack deflections caused by the coupling of specimen orientations and crack sizes significantly increase the challenge to magnesium alloy evaluation. In this paper, the systematic finite element analysis was conducted for compact tension (CT) specimens with deflection cracks. A wide range of geometric variations including initial crack length, crack deflection angle and crack propagation length were analyzed. Complete solutions of the stress intensity factor (KI and KII), T-stress and the compliance at the load line were determined. The results showed that the geometric sizes have a significant coupling effect on the fracture mechanics parameters, and the non-deflected cracked formula recommended by the ASTM standard is not applicable to the deflection crack specimens. Then, a prediction method of kinked fatigue crack length of CT specimen based on the compliance multiplier method was proposed. To further verify the importance of the fracture parameters obtained, CT fatigue crack growth (FCG) tests of ZK60 magnesium (Mg) alloy under different orientations and initial crack sizes were carried out. The FCG rate curves of ZK60 Mg alloy under different crack growth driving forces were compared and illustrated. The developed compliance multiplication method can accurately predict the real-time crack propagation length.

Flexural behavior of precast lightweight aggregate concrete insulation panels

This study examined the effect of different panel-to-base connection techniques on the flexural behavior of precast lightweight aggregate concrete (PLC) panels with an embedded honeycomb cardboard for lighter weight and better insulation performance. Eight full-size PLC insulation panels were prepared with test parameters including panel-to-base connection techniques, the compressive strength of concrete (fc′), and continuity of span. All panel specimens were tested under symmetrical two-point top loadings in each span. The test results revealed that the flexural design process specified in the code American Concrete Institute 318-19 commonly underestimated the flexural cracking and moment capacity of the PLC specimens. The PLC insulation panel specimens with an fc′ exceeding 13 MPa could be classified into grade 1 as specified in the code KS F 4736, indicating a good flexural resistance. For conservative flexural design of PLC insulation panels, the use of the conventional spliced connection and modified spliced sleeve connection could be considered as a fixed end, whereas the use of screw-bolt-and-spring connections could be considered as a hinged end. The displacement ductility ratios of PLC insulation panels with an fc′ of 24.5 MPa were approximately 1.2 times higher than those of the counterpart PLC insulation panels with an fc′ of 13 MPa, because more severe cracks along the insulation materials were observed in the specimens with lower fc′ values.

Crack Detection of Asphalt Concrete Using Combined Fracture Mechanics and Digital Image Correlation

Cracking is a common failure mode in asphalt concrete (AC) pavements. Many tests have been developed to characterize the fracture behavior of AC. Accurate crack detection during testing is crucial to describe AC fracture behavior. This paper proposes a framework to detect surface cracks in AC specimens using two-dimensional digital image correlation (DIC). Two significant drawbacks in previous research in this field were addressed. First, a multiseed incremental reliability-guided DIC was proposed to solve the decorrelation issue due to large deformation and discontinuities. The method was validated using synthetic deformed images. A correctly implemented analysis could accurately measure strains up to 450%, even with significant discontinuities (cracks) present in the deformed image. Second, a robust method was developed to detect cracks based on displacement fields. The proposed method uses critical crack tip opening displacement (δc) to define the onset of cleavage fracture. The proposed method relies on well-developed fracture mechanics theory. The proposed threshold δc has a physical meaning and can be easily determined from DIC measurement. The method was validated using an extended finite-element model. The framework was implemented to measure the crack-propagation rate while conducting the Illinois-flexibility index test on two AC mixes. The calculated rates could distinguish mixes based on their cracking potential. The proposed framework could be applied to characterize AC cracking phenomenon, evaluate its fracture properties, assess asphalt mixture testing protocols, and develop theoretical models.

An experimental study and theoretical evaluation on the effect of specimen geometry and loading configuration on recorded fracture toughness of brittle construction materials

Geometry and loading condition of cracked specimens may affect the fracture toughness results and hence the evaluation of differences in measured fracture toughness values is necessary for many construction materials. In the absence of standard methods for measuring the general mode fracture resistance of asphaltic concrete materials, in this study the fracture toughness values for such materials were measured and compared by means of three different test specimens and methods. All three fundamental fracture modes (i.e. pure I, pure II, and pure III) and related mixed-mode loading cases (i.e. I/II and I/III) were evaluated. The test specimens were edge-notched disc bend (ENDB), edge-notched diametrically compressed disc (ENDC), and semi-circular bend (SCB). During the experimental program the specimens made of asphaltic concrete were tested at two temperatures of −5 and −25 °C and analyzed using the linear elastic fracture mechanics (LEFM) principles. Also, several theoretical frameworks were compared and examined to evaluate their applicability and accuracies for predicting the trends of experimentally obtained test data. The results showed that the geometry and loading configuration can significantly affect the measured fracture toughness values under pure mode II and pure mode III. The value of mode I fracture toughness measured by three specimens was almost the same (with small differences of 4%) and equal to 0.68 MPa√m. At pure mode II, the fracture toughness evaluated by the ENDB specimen was about 20% higher than that of the SCB specimen (with averages of 0.83 and 0.68 MPa√m for the ENDB and SCB samples, respectively). For pure mode III case, the measured fracture toughness by the ENDC specimen was approximately 60% higher than that of the ENDB specimen (with averages KIIIc = 0.62 MPa√m for the ENDC and 0.42 MPa√m for the ENDB specimen). Among the investigated mixed mode fracture criteria, the GMTS criterion provided accurate predictions for KIIc/KIc ratios. Also, 3D-MTSN, and 3D-MTSED criteria were more precise than others for mode I/III predictions. The evaluations indicated that the discrepancy between the measurements is mainly due to sign and magnitude of T-stress parameter.

A coupled diffusional-mechanical model accounting for hydrogen enhancements of strain-induced dislocations and vacancies

Informed by the current understanding of hydrogen-dislocations/vacancies interactions, a coupled diffusional-mechanical model accounting for hydrogen-enhanced strain-induced dislocations and vacancies is developed. This model is applied to capture hydrogen diffusion and trapping in the uniaxially tensioned column and type-I loaded crack specimens of nickel alloy, with special attentions paid to the influence of hydrogen-vacancies interaction on them, which is seldom discussed in previous studies. The results show that the hydrogen-enhanced hardening rate and the hydrogen-promoted vacancy enrichment for the nickel alloys observed in experiments can be addressed well by the present model. The strain-induced vacancies rather than dislocations dominate the hydrogen trapping behavior, due to their higher hydrogen binding energies for the nickel alloy. The hydrogen-saturated state of vacancies can heavily impact hydrogen diffusion/trapping, which could be characterized by the effective trap concentration. The supersaturated vacancies caused by hydrogen-enhanced strain-induced vacancies can promote void growth through vacancy condensation, thus accelerating plastic localization or interface rupture. For the type-I loaded blunt crack specimen, the hydrogen-enhanced dislocation multiplication contributes to intergranular cracking in the pressure valley, while hydrogen-enhanced vacancy generation facilitates void growth in the plastic zone, both of which can exacerbate plastic localization ahead of crack tip. A quantitative model for plasticity localization that accounts for the influences of hydrogen-induced IG cracking and void growth would be helpful in physically based modeling of hydrogen embrittlement.

Experimental Research into the Repair of High Temperature Damage to Cement Mortar Samples Using Microbial Mineralization Technology

Experiments such as microbial activation culture, subculture selection, and fire damage repair of cement mortar specimens were conducted to investigate the repairing effect of Sporosarcina pasteurii as a repair agent for fire-damaged cracks in cement mortar specimens. In addition, multi-scale parameters such as compressive strength and chloride ion migration coefficient of cement mortar specimens before and after restoration were compared. The effect of microbial mineralization technology on the repair of fire-damaged cracks in cement mortar specimens was investigated, and the microstructure and mineral composition of the products were analyzed. The results showed that the strong alkaline environment in the cracks of the cement mortar specimens after a high temperature of 500 °C inhibited the activity of bacteria and weakened the mineralization effect; the compressive strength of the repaired cement mortar specimens was 22.8% higher than that of the unrepaired fire-damaged specimens; the compressive strength of the repaired cement mortar reached 78.2% of the strength of the original cement mortar specimen without high temperature; after restoration, the chloride ion penetration resistance of the cement mortar specimens decreased by about 16.9% compared with that before restoration.

Experimental study on local crack propagation of concrete under three-point bending

To investigate the propagation process of local cracks in concrete, three-point bending tests were performed on the beams with a local rectangular pre-crack. Pre-cracks with different sizes were set in the specimens with the widths ranging from 30 mm to 100 mm and the heights ranging from 30 mm to 60 mm. The three-point bending tests were carried out with a controlled displacement rate of 0.024 mm/min. The compressive strength, elastic modulus and tensile strength of the concrete were 40.89 MPa, 32.57 GPa and 3.40 MPa, respectively. By monitoring the initiation and propagation of local cracks on the specimen surfaces, the fracture toughness of the concrete specimen with a local crack was determined and the crack propagation process along the thickness and height directions was investigated. The experimental results indicated that, under three-point bending loading, the local cracks always propagated firstly on the bottom surface of the specimen and formed a through crack in the thickness direction. After that, the crack in the specimen began to propagate in the height direction until full failure. In addition, the initial fracture toughness obtained from the specimens with bottom-through cracks was almost the same as the one from the specimens with local cracks. However, the unstable fracture toughness obtained from the specimens with bottom-through cracks was not consistent with the one from the specimens with local cracks, where the average unstable fracture toughness calculated using the critical crack lengths at different thicknesses was taken as the unstable fracture toughness of the local crack specimens. This indicated that the initial fracture toughness could be considered as a material characteristic, while the unstable fracture toughness was dependent on the crack geometry.

Experimental study on fracture and acoustic emission properties of internally cured concrete with super absorbent polymer subjected to high temperature

The three-point bending experiment was conducted on notched beams containing five different SAP contents to investigate the influence of high temperature on the fracture performance of Superabsorbent Polymer (SAP) concrete. Acoustic Emission (AE) technology was employed to monitor real-time crack propagation, and scanning electron microscopy (SEM) was utilized to analyze the micro-pore structure. The experimental results reveal the following findings. After exposure to high temperatures, the peak strength of SAP concrete continuously decreases. Compared to specimens at 20 °C, the strength loss after exposure to temperatures of 200 °C, 400 °C, and 600 °C is approximately 11%, 55%, and 87%, respectively. However, the introduction of SAP can reduce the proportion of strength loss in the concrete. Additionally, SAP improves the toughness of the concrete, with an increase in ductility coefficient ranging from 4.0 to 6.8 times as the loading temperature increases. Similar to the strength variation pattern, the initial fracture toughness of SAP concrete exhibits a significant decrease with increasing heating temperature. The loss in initiation toughness after exposure to temperatures of 200 °C, 400 °C, and 600 °C is approximately 11%, 42%, and 85%, respectively, while the loss in unstable fracture toughness is 11%, 46%, and 74%. Based on the experimental results, this study proposes two temperature-dependent fitting models for the peak strength and fracture toughness of SAP concrete, which are compared and validated with the experimental results. SEM analysis reveals a loose and porous internal structure in SAP concrete. Through the analysis of AE signals at different temperatures, the fracture process is elucidated based on the b-value method. Moreover, RA-AF analysis indicates that an increase in temperature reduces the proportion of tensile-type cracks in specimens with the same SAP content. From the temperature loaded results spanning 20 °C–600 °C, the proportion of tensile cracks decreases from 80% to 50%, indicating a transition in the failure mode from tension to shear. However, this trend is not significantly affected by the temperature increase, suggesting that the failure mode of the specimens is primarily determined by the internal pore structure of the concrete rather than the temperature load. The research findings provide experimental evidence for the application of SAP concrete in engineering projects.

Experimental and Numerical Prediction of Surface Crack Growth in Fatigue in a Finite Width Plate

In the thick components such as gas turbine disks, the cracks usually manifest in the form of part-through or embedded elliptical cracks. The shape of surface crack varies during the crack propagation and significantly affects the fatigue life predictions of the surface cracked components. In present work, crack propagation of semi-elliptical cracks in a finite width specimen of a gas turbine material subjected to fatigue load has been studied experimentally and numerically. The numerical simulation was accomplished by first extending the applicability of available stress intensity factor empirical equation for semi-elliptical cracks to finite width solid. Using this empirical equation for stress intensity factor, the effect of change in the crack shape on the crack propagation life is simulated by numerical models. Also, in order to include the effect of crack closure in the numerical prediction of growth of surface cracks, a ratio of crack closure factor between depth and surface locations of a semi-elliptical crack was obtained by experiments. The experimental observations were used in correlating the numerical predictions for crack shape progression and crack propagation life.

Monitoring crack tip position in Cracked Lap Shear specimens subjected to fatigue loading

In recent years, interest in adhesively bonded joints has significantly grown, as it offers numerous advantages with respect to other joining techniques. Bonded joints are being increasingly adopted in structures subjected to fatigue loading, which might initiate and propagate crack-like debonding defects. The ability to detect and locate these defects is crucial for increasing overall safety. This study aims to investigate the capability of two commonly used Non-Destructive techniques, namely Digital Image Correlation and Visual Testing, to correctly locate the crack tip of a debonding damage. For this purpose, a specific Cracked Lap Shear specimen, which features mixed mode I-II loading conditions, was designed, manufactured, and tested under fatigue loading. Two different adhesives were used. The results showed that Digital Image Correlation was able to easily identify the crack tip, while visual inspection proved to have some difficulties due to the prevalence of mode II, which makes crack identification more troublesome.

Electro-Mechanical Impedance-Based Structural Health Monitoring of Fiber-Reinforced Concrete Specimens under Four-Point Repeated Loading

Fiber Reinforced Concrete (FRC) has shown significant promise in enhancing the safety and reliability of civil infrastructures. Structural Health Monitoring (SHM) has recently become essential due to the increasing demand for the safety and sustainability of civil infrastructures. Thus, SHM provides critical benefits for future research to develop more advanced monitoring systems that effectively detect and diagnose the damage in FRC structures. This study investigates the potential of an Electro-Mechanical Impedance (EMI) based SHM system for detecting cracks in FRC prisms subjected to four-point repeated loading. For the needs of this research, an experimental investigation of three FRC specimens with the dimensions 150 × 150 × 450 (mm) were subjected to three different loading levels where no visual cracks formed on their surface. Next, prisms were subjected to reloading until they depleted their load-carrying capacity, resulting in pure bending fracture at the mid-span. A network of nine cement paste coated Piezoelectric lead Zirconate Titanate (PZT) transducers have been epoxy bonded to the surface of the FRC prisms, and their frequency signal measurements were utilized for quantitative damage assessment. The observed changes in the frequency response of each PZT sensor are evaluated as solid indications of potential damage presence, and the increasing trend connotes the severity of the damage. The well-known conventional static metric of the Root Mean Square Deviation (RMSD) was successfully used to quantify and evaluate the cracking in FRC specimens while improving the efficiency and accuracy of damage detection. Similarly, the dynamic metric of a new statistical index called “moving Root Mean Square Deviation” (mRMSD) was satisfactorily used and compared to achieve and enhance accuracy in the damage evaluation process.