Predictability of concrete damage level by non-destructive test methods

Ultrasonic pulse velocity and resonance frequency methods are non-destructive tests that allow the evaluation and control of building materials. They have been used to determine the dynamic properties of concrete, which are used in the design and control of structures and which are the key elements of the dynamics of materials. In this study, we chose a non-destructive approach to quantify -in laboratory-, the influence of adding “silica fume” on ordinary concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental plan used, allowed us to determine the dynamic elasticity modulus and the dynamic rigidity modulus of different formulated concretes.

Stabilized mixes are used in the construction of bearing layers in asphalt and concrete pavement structures. Two nondestructive methods: resonant frequency method and ultrasonic pulse velocity method, were used for estimation of elastic properties of fly ash–stabilized mixes. Stabilized mixes were designed containing sand from the river Drava and binder composed of different share of cement and fly ash. The aim of the research was to analyze the relationship between the dynamic modulus of elasticity determined by different nondestructive methods. Data showed that average value of elasticity modulus obtained by the ultrasound velocity method is lower than the values of elasticity modulus obtained by resonant frequency method. For further analysis and enhanced discussion of elastic properties of fly ash stabilized mixes, see Dimter et al. [1].

Ultrasonic evaluation of the physical and mechanical properties of granites

The durability of concrete irrigation infrastructures decreases easily due to environmental effects, such as the freeze-thawed process. The degree of damage in concrete is, in most cases, evaluated by an unconfined compression test or ultrasonic test. The limiting states of structures are the result of a gradual accumulation of microdefects during the in-service period, which leads to the initiation and development of macroscopic cracks, loss of performance, and Failure. Therefore, to maintain such structures, it is necessary to properly determine the degree of damage by non-destructive testing. For effective maintenance and management of in-service structures, it is necessary to evaluate not only such mechanical properties as strength but also the degree of damage. Quantitative damage evaluation of concrete is proposed by applying the X-ray CT method and related non-destructive inspection, which is based on estimating cracking damage effects. In this study, the damage evaluation of concrete-core samples is investigated by X-ray CT parameters and the non-destructive parameters. The samples tested were taken from the damaged concrete headwork in Niigata, Japan, about 50 years after its construction. The geometric properties of the concrete matrix were calculated by the analysis of X-ray CT images. After X-ray CT measurement, an ultrasonic test and a resonant frequency test were performed. The dynamic modulus of elasticity was calculated by using ultrasonic pulse velocity and resonant frequency. As a result, based on the relationship between the geometric properties of the concrete matrix and the non-destructive parameters, the accumulation of damage in the samples tested was correlated with the ratio of the total area of cracks to the observation area. In damaged conditions, the high value of its ratio is demonstrated under low ultrasonic pulse velocity. These results suggest that the most sensitive components in a concrete body to the degree of damage are cracks in mortar and the ratio of the total area of cracks to the observation area. These values are affected by the internal actual cracks. Thus, the damage of concrete could be quantitatively evaluated by the geometric properties of the concrete matrix and its physical properties.

Cemented paste backfill (CPB) plays an important role in sustainable mining by providing structural support and reducing surface subsidence. While traditional destructive testing methods such as unconfined compressive strength (UCS) tests offer valuable understanding of material strength, they require a lot of resources, are time-consuming, and environmentally unfriendly. However, non-destructive testing (NDT) techniques such as ultrasonic pulse velocity (UPV), electrical resistivity (ER), and acoustic emission (AE) provide sustainable alternatives by preserving sample integrity, minimizing waste, and enabling real-time monitoring. This study systematically reviews and quantitatively compares the effectiveness of UPV, ER, and AE in predicting the strength of CPB. Meta-analysis of 30 peer-reviewed studies reveals that UPV and AE provide the most consistent and reliable correlations with UCS, with R2 values of 0.895 and 0.896, respectively, while ER shows more variability due to its sensitivity to environmental factors. Additionally, a synthetic model combining UPV, AE and ER demonstrates improved accuracy in predicting strength. This hybrid approach enhances predictions of material performance while supporting sustainability in mining and construction. Our research advocates for better testing practices and presents a promising direction for future infrastructure projects, where real-time, non-invasive monitoring can enhance material performance evaluation and optimize resource use.

Assessing alkali-silica reaction damage to concrete with non-destructive methods: From the lab to the field

Adhesion assessment between epoxy resin and concrete substrate is described in the article. Two-layered cylindrical elements were obtained from the borehole in the object created for the purpose of the test. Adhesion analysis has been performed for two groups of elements of different composition. The ultrasonic pulse velocity (UPV) method with two-sided access was used to assess the adhesion. Pull-off adhesion fb compared with the ultrasonic wave velocity V has been determined. Relationships between the ultrasonic wave velocity V and pull-off adhesion fb, obtained with the semi-destructive pull-off method, were determined for both groups of elements. It was proved that together with an increase on the elements of the ultrasonic velocity wave V, the pull-off adhesion value fb between the epoxy resin and the concrete substrate also increases.

This paper concerns the evaluation of the pull-off adhesion between a concrete added repair layer with variable thickness and a concrete substrate, based on parameters assessed using ultrasonic pulse velocity (UPV) method. In construction practice, the experimental determination of pull-off adhesion fb, between added repair layer and a concrete substrate is necessary to assess the quality of repair. This is usually carried out with the use of pull-off method which results in local damage of the added concrete layer in all the testing areas. Bearing this in mind, it is important to describe the method without these disadvantages. The prediction of the pull-off adhesion of the two-layer concrete elements with variable thickness of each layer might be provided by means of UPV method with two-sided access to the investigated element. For this purpose, two-layered cylindrical specimens were obtained by drilling the borehole from a large size specially prepared concrete element. Those two-layer elements were made out of concrete substrate layer and Polymer Cement Concrete (PCC) mortar as an added repair layer. The values of pull-off adhesion fb of the elements were determined before obtaining the samples by using the semi-destructive pull-off method. The ultrasonic wave velocity was determined in samples with variable thickness of each layer and was then compared to theoretical ultrasonic wave velocity predicted for those specimens. The regression curve for the dependence of velocity and pull-off adhesion, determined by the pulloff method, was made. It has been proved that together with an increase of ratio of investigated ultrasonic wave velocity divided by theoretical ultrasonic wave velocity, the pull-off adhesion value fb between added repair layer with variable thickness and a substrate layer also increases.

The vast growt of population now increases the usage of buildings and infrastructures especially for concrete bridge. Prestressed concrete was introduced to be used in most concrete bridge superstructures. Predetermination of concrete strength ensures the condition of precast prestressed concrete structures. Testing of precast concrete is crucial in order to find its capabilities before commencing construction. Conventional method of testing usually takes a lot of time and is very costly. The aim of this study is to find the speed of the sound wave passing through the precast prestressed concrete beam. This study also identifies the shear modulus and the elastic modulus of precast prestressed concrete beam after the application of bending test on the two rectangular beams of 4 m length each. The test result indicates the condition of the beam, before and after loading condition. The ultrasonic pulse velocity (UPV) method is an ideal tool to show whether concrete structure is in good condition. This method can be used for those still been constructed and on existing structures. Interpretation of velocities using UPV method could easily determine the grading in terms of its uniformity and strength. The velocities indicate the occurrence of voids inside the beam which relates to the tendency of initial failure. Decreases in ultrasonic waves speed over time can reveal the onset of damage before visible deficiencies become evident. This allows inspectors and engineers to implement repair recommendations before minor deficiencies become safety hazards.

In this study, the ultrasonic pulse velocity (UPV) method was used to evaluate the residual mechanical properties of non-sintered Hwangto concrete exposed to high temperatures. The effect of the replacement ratio of non-sintered Hwangto concrete (0 15, and 30%) on the residual mechanical properties was evaluated, with compressive strength and UPV set as the evaluation parameters. The experimental results showed that the residual mechanical properties of the specimens exhibited similar trends with increasing temperature, regardless of the non-sintered Hwangto concrete replacement percentage. Regression analysis revealed a strong linear relation between the variables. An error test indicated that the influence on the target strength was the highest, and analysis with the existing prediction model suggested the need for a prediction model specifically for non-sintered Hwangto concrete.

In this study, the mechanical properties of normal concrete (NC) and lightweight concrete (LC) were measured upon exposure to high temperatures (20, 100, 200, 300, 500, and 700 °C). Then, analysis was conducted to predict the residual modulus of elasticity through ultrasonic pulse velocity. Crushed granite aggregate was mixed as the coarse aggregate for NC and coal-ash aggregate for LC. The effect of the water-to-binder (W/B) ratio (0.41, 0.33, and 0.28) on the mechanical properties (residual compressive strength, residual ultrasonic pulse velocity, residual modulus of elasticity, and stress–strain) of concrete was determined. The residual compressive strength, residual ultrasonic pulse velocity, and residual modulus of elasticity were higher for LC compared to NC. The correlation between the ultrasonic pulse velocity and residual modulus of elasticity was also analyzed, which yielded a high correlation coefficient (R2) at all levels. Finally, equations for predicting the residual modulus of elasticity using ultrasonic pulse velocity with R2 values of 0.94 and 0.91 were proposed for NC and LC, respectively.

Ultrasonic testing (UT) is an important method for concrete, and ultrasonic pulse velocity is commonly used to evaluate the quality of concrete materials in existing studies. The ultrasonic pulse velocity of concrete materials is affected by many factors; therefore, it is necessary to establish a quantitative prediction model for the ultrasonic pulse velocity of concrete materials. Based on the multiscale homogenization method, concrete material is divided into different scales of homogenized materials, namely cement paste, mortar, and concrete. Then, a multiscale ultrasonic pulse velocity model is established through a combination of elasticity formulation and the hydration model. At the three scales of cement paste, mortar, and concrete, the elastic parameters and ultrasonic pulse velocity were predicted with the water-to-cement ratio of 0.35, 0.5, and 0.65, respectively. The ultrasonic pulse velocity of concrete with different water-to-cement ratios and different ages were measured in the test and predicted by the model. The results show that the predicted value of ultrasonic pulse velocity is within the error range of ±1.5% of the measured ultrasonic pulse velocity, suggesting that the established prediction model of ultrasonic pulse velocity can reliably predict the velocity change in concrete materials.

The adhesive interface in new-to-old concrete widely occurs in the concrete structure, and the adhesion assessment for freeze-thaw (F-T) resistance is hardly focused on. To evaluate the F-T resistance of adhesive interfaces in new-to-old concrete with a nondestructive method, this experiment was conducted with ultrasonic pulse velocity (UPV). Specimens with the same natural roughness were obtained using three-dimension printing technology. The surface roughness was measured via the sand replacement method. The traditional evaluation that the decrease of relative dynamic elastic modulus under 60 % represents the failure of concrete F-T resistance has a limitation in new-to-old concrete structures. A new characterization method of F-T resistance in adhesive interface for new-to-old concrete was proposed based on the variation trend of UPV in parallel direction (UPV-PD) and vertical direction (UPV-VD). The UPV-VD loss ratio had a three-stage characteristic and a steady phase, which was different from the loss ratio of splitting tensile strength in numerical value. The results showed that the UPV-PD loss ratio grew linearly in the process of F-T cycles. Moisture content was the dominant influence on the numerical difference. This difference can be eliminated based on a correction method. The variation trend of the UPV loss ratio in adhesive interfaces was similar to that of splitting tensile strength, and the obvious turning points appeared after similar F-T cycles. The characterization method of F-T resistance proposed in this article is applicable to evaluate the F-T resistance of adhesive interfaces in new-to-old concrete, which is also proved by splitting tensile test results.

Quantitative analysis of termites damage is important in terms of conservation and maintenance of wooden cultural heritage buildings, because termites makes cavities and decreases the section area of wooden structural members. The purpose of this study is to forecast the range and spread of termites damage in the wooden structural members by using ultrasonic pulse velocity method. Ultrasonic pulse velocity has been used as one of non-destructive test to analysis the internal defect by using difference velocity between medium material and cavity. This method would be effective to analysis termites damages. From the result of the ultrasonic velocity test, the loss rate of area effected by termites damage had a strong correlation with ultrasonic velocity. And it is possible to predict the loss rate of area from by termites damage by using regression equation in the case of structural member of fine tree.

As the lifespan of concrete structures increases, their load carrying capacity decreases owing to cyclic loads and long-term effects such as creep and shrinkage. For these reasons, there is a necessity for stress state monitoring of concrete members. Particularly, it is necessary to evaluate the concrete structures for behavioral changes by using a technique that can overcome the measuring limitations of usual ultrasonic nondestructive evaluation methods. This paper proposes the use of a nonlinear ultrasonic method, namely, nonlinear resonant ultrasonic spectroscopy (NRUS) for the measurement of nonlinearity parameters for stress monitoring. An experiment compared the use of NRUS method and a linear ultrasonic method, namely, ultrasonic pulse velocity (UPV) to study the effects of continuously increasing loads and cyclic loads on the nonlinearity parameter. Both NRUS and UPV methods found a similar direct relationship between load level and that parameter. The NRUS method showed a higher sensitivity to micro-structural changes of concrete than UPV method. Thus, the experiment confirms the possibility of using the nonlinear ultrasonic method for stress state monitoring of concrete members.