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- MakaleYalnız künye2026Scopus SJRQ1Mechanical properties of polypropylene fiber-reinforced shotcrete based chromite flotation waste using a nondestructive testing method
Aksüt, Yavuz Selim; Seferoğlu, Mehmet Tevfik
This study examines the mechanical behavior and non-destructive assessment of shotcrete reinforced with polypropylene fibers (PPFs) and incorporating chromite flotation waste (CFW) as a partial substitute for fine aggregate. Shotcrete mixtures were prepared with four CFW replacement levels (0–30%) and four PPFs volume fractions (0–1%) and their compressive strength, splitting tensile strength and static modulus of elasticity were evaluated. Poisson's ratio and ultrasonic pulse velocity (UPV) were experimentally determined. The effect of fiber reinforcement and waste incorporation on the mechanical behavior was evaluated through statistical correlation, simple regression and multivariable predictive modeling approaches. The results showed that moderate PPFs contents (0.25–0.5%) generally enhanced compressive and tensile performance while excessive fiber dosage (1%) led to strength and stiffness reductions due to increased heterogeneity, fiber agglomeration and void formation at high CFW replacement levels. Increasing CFW content resulted in systematic reductions in UPV values with an average decrease of approximately 3–4% per 10% CFW replacement indicating changes in matrix continuity and internal structure. However, these UPV reductions were not directly proportional to losses in mechanical strength or elastic stiffness. Correlation analyses revealed weak to moderate relationships between UPV and mechanical properties confirming that UPV alone is insufficient to represent the complex behavior of fiber-reinforced, waste-based shotcrete systems. Simple UPV-based regression models exhibited limited predictive capability for both compressive strength (R2 ~ 0.16) and static modulus of elasticity (R2 ~ 0.002). In contrast, multivariable regression models incorporating normalized UPV, CFW replacement ratio and PPFs volume fraction together with their interaction terms, significantly improved prediction accuracy. The proposed models achieved high coefficients of determination (R2 ~ 0.86 for compressive strength and R2 ~ 0.97 for static elastic modulus) with substantially reduced root mean square error (RMSE) values. Finally, the findings demonstrate that UPV can be effectively used as a non-destructive indicator for estimating the strength and stiffness of PPFs reinforced shotcrete incorporating CFW only when material specific parameters are explicitly considered.
- MakaleYalnız künye2018Scopus SJRQ2A New Nomogram Proposal to Determine Concrete Compressive Strength by Combined Nondestructive Testing Methods
Bingöl, Şinasi; Çavdar, Ahmet
Concrete is the most widely used construction material in contemporary construction technology. In particular, it holds an important place in the building industry in the world. Since concrete is a nonhomogeneous material, determining the strength of concrete accurately is quite difficult. In this respect, to check the mechanical properties of concrete in-situ, nondestructive test (NDT) methods can be used. They are useful as they do not damage concrete; however, these test results are sometimes deceptive. To reduce these deceptive results, destructive test methods were proposed to increase the accuracy of nondestructive methods. The objective of this study is to determine the strength of concrete with different characteristic strengths using destructive and NDT methods, and to establish new relationships between the compressive strength of concrete and Schmidt rebound values, and ultrasonic wave velocities. For this purpose, 101 concrete cube samples were prepared. After 7 and 28 days of curing, Schmidt rebound and ultrasonic wave velocity tests were applied as NDT methods. New formulations and graphs were established by carrying out a multiple regression analysis between the ultrasonic wave velocities, Schmidt rebound values, and compressive strengths. Thus, a new combined NDT method was developed with a nomogram. Furthermore, the applicability and accuracy of the formula and graph obtained were investigated by comparing the results of core samples from existing structures. The most important findings obtained from the study are summarized below. The concrete strength can be determined with nondestructive formulas obtained with an accuracy of 85%. High strength concrete cube samples are obtained in-house with 1.6% deviation, and core samples in-situ can be obtained with 7.3% deviation with the newly developed NDT nomogram. These test results show that the newly developed NDT formulas in this study are a very good alternative for determining concrete strength in-situ.
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İncele - MakaleYalnız künye2012Scopus SJRQ2Seismic Performance Assessment of Masonry Tile Domes through Nonlinear Finite-Element Analysis
Atamturktur, S.; Sevim, B.
This article discusses a combined analytical and experimental study on the nonlinear seismic performance of two Guastavino-style masonry domes located in the United States. The seismic performance of these masonry domes is simulated with nonlinear finite-element (FE) models. To support the assumptions and decisions established during the development of the FE models, the vibration response of the domes is measured on-site and systematically compared against the numerical model predictions. Linear FE models are developed that are in close agreement with the measured natural frequencies and in visual agreement with the measured mode shapes. Next, these linear models are extended into the nonlinear range by incorporating the Drucker-Prager damage criterion. Finally, nonlinear FE models are used to assess the performance of these two domes under seismic loadings obtained from the 1940 El Centro earthquake acceleration records. The predicted displacements and internal tensile stress levels are used to make inferences about the potential behavior of these two buildings under the selected earthquake load. DOI: 10.1061/(ASCE)CF.1943-5509.0000243. (C) 2012 American Society of Civil Engineers.
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