scholarly journals NDT Methods Suitable for Evaluation the Condition of Military Fortification Construction in the Field

2020 ◽  
Vol 10 (22) ◽  
pp. 8161
Author(s):  
Zezulová Eva ◽  
Hasilová Kamila ◽  
Komárková Tereza ◽  
Stoniš Patrik ◽  
Štoller Jiří ◽  
...  
Keyword(s):  
Residual Strength ◽  
Fiber Reinforced Concrete ◽  
Protective Structure ◽  
Steel Fiber Reinforced Concrete ◽  
Degree Of Damage ◽  
Materials Used ◽  
Protective Structures ◽  
The Impact ◽  
Non Destructive

The protective structure is designed to protect the live force against the impact of a shock wave and projectiles, it cannot be diagnosed by the destructive method which devalues the protective structure by sampling. The authors are looking for a combination of suitable non-destructive technology (NDT) methods that would be used in the future to prove the degree of damage to cement-based protective structures after an explosion. This article represents the first part of an experiment designed to verify the applicability of NDT methods, to evaluate the degree of damage of the protective structure in the field. The experiment consists of three parts. The first part is a laboratory verification of the initial material characteristics of the materials used. The first test set of structural elements is made of steel fiber-reinforced concrete. The elements are evaluated using NDT methods and for comparison by destructive laboratory methods. The second part is the impact of structures using explosion and evaluation of the condition of structures using NDT methods in the field. The last part is used to verify the results of the NDT method, which ensures the residual strength of the structure in the laboratory and try to find the relationship between changes in the results of NDT methods and the residual strength. Radiography was included in the introductory and concluding parts of the experiment to verify the results. Although this method is not suitable for using in-situ, it is the only standardized method of the NDT methods used.

scholarly journals Susceptibility of earth-based construction materials to fungal proliferation: laboratory and in situ assessment

2019 ◽  
Vol 3 ◽  
pp. 140-149 ◽  
Author(s):  
Alexis Simons ◽  
Alexandra Bertron ◽  
Christophe Roux ◽  
Aurélie Laborel-Préneron ◽  
Jean-Emmanuel Aubert ◽  
...  
Keyword(s):  
Air Quality ◽  
Manufacturing Process ◽  
Building Materials ◽  
Construction Materials ◽  
Microbial Density ◽  
Microbial Proliferation ◽  
Materials Used ◽  
Ecological Construction ◽  
The Impact

The impact of building materials on the environment and the health of occupants is nowadays a priority issue. Ecological construction materials such as earthen materials are currently experiencing a regain of interest due to both ecological and economic factors. The microbial proliferation on indoor materials can induce a deterioration of the building air quality and lead to an increase of health risks for the occupants. The issue of indoor air quality raises questions about the use of earthen building materials and their possible susceptibility to fungal development. The microflora of earthen materials and their ability to grow on such support are indeed poorly studied. This study focused on the quantification of both bacterial and fungal microflora along the manufacturing process. The impact of extreme humidity, simulating a hydric accident, on microflora development was analyzed on the surface and inside earthen bricks. The initial microflora of these materials was dramatically reduced during the manufacturing process, especially after heat treatment for drying. Proliferation of remaining microorganisms was only observed under high humidity condition, in particular for earthen materials with vegetal aggregates. Moreover, in situ samplings were performed on naturally dried earthen materials used in buildings. The characterization of the microbial density revealed a higher microbial density than on manufactured specimens, while microbial concentration and detected taxa seemed mainly related to the room use and building history. These results provide a better understanding of microbial proliferation on these materials.

scholarly journals NDT ASSESSMENT OF EXISTING CONCRETE STRUCTURES: SPATIAL ANALYSIS OF REBOUND HAMMER RESULTS RECORDED IN-SITU

2015 ◽  
Vol 7 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Adorján Borosnyói
Keyword(s):  
Spatial Analysis ◽  
Surface Hardness ◽  
Hardness Measurement ◽  
Optical Recording ◽  
Destructive Testing ◽  
Rebound Hammer ◽  
Schmidt Rebound Hammer ◽  
The Impact ◽  
Non Destructive

A comparative spatial analysis of surface hardness of structural concrete is introduced. Main objective of the paper is to make a repeatability comparison of three types of the still most popular non-destructive testing devices for concrete: L-type original Schmidt rebound hammer, N-type original Schmidt rebound hammer and N-type Silver Schmidt rebound hammer. Results indicate that the surface hardness measurement uncertainty is related to the weight of the hammer mass and is apparently not related to the impact energy of the rebound hammer devices. It is observed that the measure of surface hardness for the Silver Schmidt rebound hammer (Q-value) does not have positive correlation to the original rebound index (R). Results indicate the best performance of the N-type original Schmidt rebound hammer in terms of stability and normality of data. Geostatistical analysis of the measured data (in terms of empirical semivariograms) highlights different statistical behaviour for the mechanical recording rebound hammers and for the electro-optical recording rebound hammer.

Discussions on the Principle to Reduce the Sliding Fall Rock Impact Force against Protective Structure

2011 ◽  
Vol 378-379 ◽  
pp. 23-26
Author(s):  
Wen Jie Niu
Keyword(s):  
Energy Dissipation ◽  
Impact Force ◽  
Bending Stiffness ◽  
Protective Structure ◽  
Steel Column ◽  
Protective System ◽  
The Impact ◽  
Non Destructive

Passive ductile protective system is widely used because of its better performance than buttress wall. This paper intends to determine the sliding fall rock impact force against a steel column at first. Then the rigid protective structure and ductile protective structure were compared. At last the hidden principle that passive ductile protective system can reduce the impact force was revealed. Results indicate that rings for energy dissipation in passive ductile protective system can significantly decrease the bending stiffness EI and decrease the impact force. Buttress wall encounters a lot more impact force than passive ductile protective system because of its bulkiness. Thus to ensure the buttress wall non-destructive, the thickness of buttress wall increases and it is not economic.

scholarly journals Transverse-Longitudinal Bending of Multilayered Concrete Rods and Steel Fiber Reinforced Concrete Rods

2021 ◽  
pp. 40-46
Author(s):  
Yu.V. Nemirovskii ◽  
S.V. Tikhonov
Keyword(s):  
Steel Fiber ◽  
Operating Conditions ◽  
Fiber Reinforced Concrete ◽  
Longitudinal Displacement ◽  
Steel Fiber Reinforced Concrete ◽  
Elastic Deformations ◽  
Longitudinal Bending ◽  
General Relations ◽  
The Impact ◽  
The Given

This paper considers the problem of transverselongitudinal bending of multilayered concrete rods with a constant cross-section under the impact of quasistatic loading and volume forces. The research is aimed to establish general relations between the distribution topology of materials in the construction and the required types of permissible operating conditions, such as permissible ultimate elastic deformations, permissible pre-destruction deformations, and maximum permissible deformations at the start of local destructions. This study demonstrates the importance of volume forces and the possibility of increasing the bearing capacity using the redistribution of materials of the investigated constructions. The given problems are solved by the Bubnov- Galerkin method. Each of the numerically calculated cases is illustrated by the graphs of the distribution of longitudinal displacement and deflections of the rods and the values of maximum and minimum deformations in each layer of the considered rods.

scholarly journals Testing an Impedance Non-destructive Method to Evaluate Steel-Fiber Concrete Samples

2018 ◽  
Vol 18 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Tereza Komarkova ◽  
Pavel Fiala ◽  
Miloslav Steinbauer ◽  
Zdenek Roubal
Keyword(s):  
Composite Material ◽  
Steel Fiber ◽  
Fiber Composite ◽  
Fiber Reinforced Concrete ◽  
Steel Fiber Reinforced Concrete ◽  
Measuring Device ◽  
Steel Fiber Concrete ◽  
Measured Sample ◽  
Non Destructive ◽  
Sample Set

Abstract Steel-fiber reinforced concrete is a composite material characterized by outstanding tensile properties and resistance to the development of cracks. The concrete, however, exhibits such characteristics only on the condition that the steel fibers in the final, hardened composite have been distributed evenly. The current methods to evaluate the distribution and concentration of a fiber composite are either destructive or exhibit a limited capability of evaluating the concentration and orientation of the fibers. In this context, the paper discusses tests related to the evaluation of the density and orientation of fibers in a composite material. Compared to the approaches used to date, the proposed technique is based on the evaluation of the electrical impedance Z in the band close to the resonance of the sensor–sample configuration. Using analytically expressed equations, we can evaluate the monitored part of the composite and its density at various depths of the tested sample. The method employs test blocks of composites, utilizing the resonance of the measuring device and the measured sample set; the desired state occurs within the interval of between f=3 kHz and 400 kHz.

Techniques of Non-Destructive Testing of Steel Fiber Reinforced Concrete

2017 ◽  
Vol 755 ◽  
pp. 153-158 ◽  
Author(s):  
Eva Zezulová ◽  
Tereza Komárková
Keyword(s):  
Reinforced Concrete ◽  
Large Scale ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Non Destructive Testing ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Destructive Testing ◽  
Measurement Devices ◽  
Non Destructive

Non-destructive testing (NDT) is seeing increasingly frequent use in civil engineering thanks to the fact that the tests are repeatable and do not cause serious damage to the material. The requirements for the development and modernization of available testing devices and methodologies are ever increasing and the testing of existing structures often requires the use of NDT. Unfortunately, every measurement and methodology has its limits and the measurement devices for the evaluation of steel fiber reinforced concrete (SFRC) are no exception. In recent decades there has been an effort to modernize and develop existing measurement devices for SFRC testing. This building material is commonly used especially in large-scale structures. Nevertheless, the technology of SFRC could seem complicated when compared with ordinary concrete and the very nature of this composite material could lead to SFRC inhomogeneity during construction. This paper describes the assessment of SFRC by more or less available methodologies and measurements utilizing non-destructive principles.

scholarly journals Abrasion Behavior of Steel-Fiber-Reinforced Concrete in Hydraulic Structures

2020 ◽  
Vol 10 (16) ◽  
pp. 5562 ◽  
Author(s):  
Yu-Wen Liu ◽  
Yu-Yuan Lin ◽  
Shih-Wei Cho
Keyword(s):  
Reinforced Concrete ◽  
Abrasion Resistance ◽  
Steel Fiber ◽  
Cementitious Material ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Hydraulic Structures ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
The Impact

This study investigated two types of abrasion resistance of steel–fiber-reinforced concrete in hydraulic structures, friction abrasion and impact abrasion using the ASTM C1138 underwater test and the water-borne sand test, respectively. Three water-to-cementitious-material ratios (0.50, 0.36, and 0.28), two impact angles (45° and 90°), plain concrete, and steel–fiber-reinforced concrete were employed. Test results showed that the abrasive action and principal resistance varied between the two test methods. The average impact abrasion rates (IARs) of concrete were approximately 8–17 times greater than the average friction abrasion rate (FARs). In general, the impact abrasion loss of the concrete surface impacted at a vertical angle was higher than that of impacted at a 45 degree angle. Moreover, the average FAR and IAR decreased when the concrete was reinforced with steel fibers. The steel fibers acted as shields to prevent the concrete material behind the fibers from abrasion, thus improving abrasion resistance. In both the underwater and waterborne sand flow methods, the resistance to abrasion of concrete without steel fibers increased as the water/cementitious material ratio (w/cm) decreased, and the concrete compressive strength also increased.

scholarly journals Electrochemical Diagnostics of Sprayed Fiber-Reinforced Concrete Corrosion

2019 ◽  
Vol 9 (18) ◽  
pp. 3763 ◽  
Author(s):  
Wioletta Raczkiewicz ◽  
Paweł Grzegorz Kossakowski
Keyword(s):  
Reinforced Concrete ◽  
Pulse Method ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Reinforcement Corrosion ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Differences Of Opinion ◽  
Concrete Elements ◽  
Non Destructive

Sprayed fiber-reinforced concrete is used in construction for the execution and repair of reinforced concrete elements. It is believed that the addition of steel fibers is most effective, due to their parameters and low costs. Some researchers, however, suggest that the addition of steel fibers can contribute to the initiation of corrosion of the main reinforcement. In consideration of the differences of opinion on the corrosion resistance of sprayed fiber-reinforced concrete, it has become necessary to analyze this issue. The article presents comparative studies of corrosion assessments of the main reinforcement in specimens made of ordinary concrete and concrete with steel fibers. The tests were performed using a semi non-destructive galvanostatic pulse method, which allows location of the areas of corrosion and estimation of the reinforcement corrosion activity. In order to initiate the corrosion processes the specimens were subjected to freezing cycles in NaCl solution. In addition, the shrinkage and compressive strength of specimens were measured, and the observation of specimen structure under a scanning microscope was performed. It was found that galvanostatic pulse method allowed estimation of the reinforcement corrosion progress. The corrosion of the main reinforcement in steel fiber reinforced concrete specimens was less advanced than in the specimens without fibers.

scholarly journals An imaging and spectroscopic methodology for in situ analysis of ceiling and wall decorations in Colonial missions in Northern Mexico from XVII to XVIII centuries

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Edgar Casanova-González ◽  
Miguel Ángel Maynez-Rojas ◽  
Alejandro Mitrani ◽  
Isaac Rangel-Chávez ◽  
María Angélica García-Bucio ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Infrared Imaging ◽  
Spanish Colonial ◽  
X Ray ◽  
Northern Mexico ◽  
Non Invasive ◽  
Materials Used ◽  
Non Destructive

Abstract Almost three hundred Spanish colonial missions—or their remains—are scattered over the vast state of Chihuahua in northern Mexico. A few of them still display painted decorations on the wood ceilings and walls. The decorated areas vary greatly, from the whole ceiling of the main aisle to just a few square meters in a lateral chapel, and so does the conservation state of the paintings. In this context, the information regarding the paintings’ composition plays a key role in the restoration and conservation processes. For the gathering of such information, we propose a combined methodology for a fast, non-destructive and non-invasive characterization of such paintings with a minimum of techniques. This methodology includes false color infrared imaging as a first approach to determine the composition of large areas of the paintings and the homogeneity of the materials used in the painted areas, followed by small area analysis by X-ray fluorescence and fiber-optics reflectance spectroscopy. This methodology was applied to characterize the elemental and molecular composition of the decorations for four missions in Chihuahua in a fast and specific manner, revealing the use of a mix of mineral and organic materials including indigo and cochineal, and detecting differences between the missions. The methodology presented here can be easily applied for the study of a wider number of missions in Chihuahua and other regions to provide outstanding information of materials, pictorial techniques and deterioration conditions.

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