Quality Control Of Concrete Structures Research Articles

Construction quality control of concrete structures in architectural engineering—A case in Shanghai, China

<p>Architectural concrete provides diverse patterns, colors, and forms, offering extensive structural and aesthetic possibilities. In China, advanced techniques such as prefabricated and precast concrete structures are increasingly utilized, delivering benefits like faster construction, reduced resource use, and improved quality control. Recent studies in China have highlighted the environmental benefits and practical considerations of incorporating recycled materials and moderate-heat Portland cement into concrete, which offer promising sustainability advantages. This study, through a case analysis in China, explored the usability, durability, manufacturing costs, and economic implications of architectural concrete. It emphasizes the critical role of architectural concrete in modern structural engineering, financial planning, and design, aiming to reduce variability in strength and uniformity between concrete batches, ensure consistent material quality, and lower maintenance costs while accelerating production. Focusing on quality control in concrete construction in Heqing, Pudong, Shanghai, this research identified unique challenges and provided insights. In Shanghai's architectural context, continuous monitoring of concrete quality is essential for structural stability and durability. This study also addressed the resilience of concrete structures in saltwater and freeze-thaw conditions, underscoring the need to consider environmental factors in quality assurance. Laboratory experiments demonstrated that composite members and deep beams of steel and concrete exhibit notable deformation and shear resistance, highlighting the importance of meticulous material selection and structural design for effective quality control.</p>

Application of Ultrasonic Tomography to detect defects in Concrete Structures

Concrete is a material widely used in civil construction for structural elements. Due to this, there is an increasing concern about the knowledge of its deterioration state and safety. This stimulates research for methods that allow the evaluation of finished structures. Through the application of Nondestructive Testing (NDT) methods, it is possible to proceed with an investigation of the concrete structures. The application of NDT can contribute to problems diagnosis and quality control of concrete structures. Ultrasound Tomography (UT) tests are an attractive and feasible research strategy. UT allows mapping of the internal section of the object from projections of the same. The tomography uses an antenna, which in turn utilizes a series of dry contact point transducers that emit shear waves into the concrete structures. From the data collected by the equipment, 3D images of the element's reflected interfaces are generated. The present study aims to detect different anomalies that can be found in reinforced concrete slabs, verifying the potential of ultrasonic tomography for the detection of these anomalies. The study was performed by the technical team of the Structural Tests and Materials Laboratory at the Federal University of Rio Grande do Sul (LEME / UFRGS).

Fibre-reinforced polymer laminate–concrete bond check with ground penetrating radar

Externally applied carbon-fibre-reinforced polymer (CFRP) laminate is a viable, economic and durable option for strengthening deteriorated, damaged or under-designed concrete structures. Effective stress transfer at the CFRP–concrete interface is an important consideration and quantitative on-site inspection of CFRP application quality is still a challenging issue. In this study, a ground penetrating radar scanning approach was used to examine the bond quality in small-scale concrete beams with flexurally applied CFRP laminates. The parameters considered included the concrete surface roughness, concrete surface voids, epoxy thickness and CFRP type. A three-point bending test and numerical modelling were used to develop simple quantitative relationships between the scanning results and the parametric combinations. Non-destructive evaluation techniques are convenient and provide valuable information for the prediction of the interfacial bond quality and the actual capacity contribution of the CFRP laminate, which will allow a higher confidence level in CFRP application quality and better quality control of concrete structures.

Application of non-destructive methods of control within the inspection of concrete structures

This paper discusses the main non-destructive quality control methods that are used in the inspection of both under construction and already existing concrete structures. Purpose of the work: to conduct a comparative analysis of non-destructive testing methods, to consider a practical example of their application in the survey of a building being reconstructed, to identify the essential points of the organization of non-destructive quality control, which must be taken into account when developing a site work execution program. Materials and methods: the application of methods of non-destructive testing, separation with spalling and the ultrasonic method of surface sounding, is considered in detail. Results: the results of the inspection of structures by the methods separation with spalling and the ultrasonic method of surface sounding are presented, the test conditions, basic requirements for correct data interpretation, and the necessary calculations are given. Recommendations are given for planning the quality control of concrete structures at the stage of organizational and technological preparation of construction. Conclusions: non-destructive quality control finds its application both in the construction of new facilities and in the inspection of existing buildings. The choice of the survey method is made at the stage of development of a site work execution program, while it is necessary to take into account the features and scope of application of a particular method, probable measurement error, it is also possible to use several methods in combination.

Establishment of Strength Prediction Equation for Concrete Containing Coal Bottom Ash Exposed to Aggressive Environment

Strength prediction of concrete under the aggressive environment requires serious attention for all kind of significant concrete structures. However, concrete built with Ordinary Portland Cement (OPC), when subjected to the aggressive environment tends to deteriorate more rapidly than their projected life. Therefore, supplementary cementitious material (SCM) need to be introduced to enhance the strength performance of concrete. However, prediction of concrete compressive strength is also an important for the safety and quality control of concrete structures. Therefore, this study aims to develop empirical equation for the prediction of compressive strength of coal bottom ash (CBA) concrete exposed to aggressive environment that represents the marine environment. In this study, practically obtained results of compressive strength were compared with the theoretical obtained compressive strength values. The developed modified equation was validated through experimental data compared with ACI 209 and SRPS U.M1.048 standards. Hence, this study proposed a modified empirical equation that could be utilized for the expectation of compressive quality of concrete containing CBA.

Evaluation of surface cracks of bending concrete using a fully non-contact air-coupled nonlinear ultrasonic technique

In this paper, a fully non-contact second harmonic generation (SHG) technique using a pair of air-coupled ultrasonic transducers is developed and the feasibility of the technique is investigated through the evaluation of surface cracks of concrete beams subjected to the bending load. The reliability of developed technique is subsequently validated by comparing the non-contact nonlinear ultrasonic measurements with measurement results based on contact-type sensors, where the coefficient of variation of non-contact measurements is averagely about 46% of the contact measurements. The defined nonlinear parameter is found to have a monotonically increasing trend with the growth of concrete crack, and the nonlinear parameter corresponding to the largest crack increases about 7 times from its initial value corresponding to the sample in intact state. In contrast, the increase of linear parameter namely the time-of-flight of surface wave is only about 40%. The difference as high as one order of magnitude verifies the high sensitivity of developed air-coupled SHG technique. With consideration of the easily removable characteristic of air-coupled ultrasonic measurements, the developed SHG technique could be promising for the large scale quality control of concrete structures in engineering practice.

Международный опыт применения интроскопических методов исследования в сельскохозяйственной биологии и пищевой промышленности

Разнообразие практических задач, решаемых на основе методов и средств интроскопии, как по своей цели и содержанию, так и по своим условиям позволяет решать проблему с помощью различных физических методов. В статье представлен аналитический обзор мирового опыта использования интроскопических методов исследования, применяемых в сельскохозяйственной биологии и пищевой промышленности. В частности, кратко рассказывается о применении интроскопии в различных областях науки и об истории развития интроскопических исследований сельскохозяйственных растений в нашей стране и за рубежом. Интроскопия широко используется в различных областях науки, например, в медицине для диагностических целей; в металлургии для исследования качества металла; в полупроводниковой технике; в гидротехнике для контроля подводных частей сооружений; в строительстве для контроля качества бетонных сооружений; для анализа функционирования узлов и механизмов; контроля багажа, почтовых отправлений, грузовых контейнеров и транспортных средств; продуктов питания и сырья; судебно-медицинской экспертизе и в анализе произведений искусства; в геологии; археологии и палеонтологии. На основании проведенного анализа можно говорить о том, что за рубежом при исследованиях большое внимание уделяется рентгеновской томографии. В нашей стране первые исследования с использованием интроскопических методов проводили в Агрофизическом научно-исследовательском институте. В настоящее время научно-исследовательских работ с использованием интроскопических методов исследований, в том числе рентгеновской томографии, мало, а исследования ограничиваются только микрофокусной рентгенографией. Сделан вывод, что в отечественной сельскохозяйственной биологии необходимо расширить научно-исследовательские работы с использованием методов интроскопии.

ВЛИЯНИЕ ХАРАКТЕРИСТИК ВНЕШНЕЙ ЦЕПИ НА ФОРМУ ЭЛЕКТРИЧЕСКОГО ИМПУЛЬСА ПРИ ОПРЕДЕЛЕНИИ ПРОЧНОСТИ БЕТОНА УДАРНО-АКУСТИЧЕСКИМ МЕТОДОМ

The axis-symmetric non-stationary problem of electric elasticity of a piezoceramic cylinder with axial polarization of the material, acting as a converter of energy in the course of the application of the shock-acoustic method of the quality control of concrete structures is considered in the article. The new closed solution represents a consecutive application of methods of finite integral transformations including the Fourier transformation based on the axial coordinate and a generalized algorithm based on the radial variable. Standardization and transformation of boundary conditions into homogeneous ones are performed at each stage. Measurements of electric impulses are taken by a voltmeter that has an electrode coating, and operates as an ideal conductor with negligible mass. The voltmeter is attached to the surface of the cylinder. Simplified electric boundary conditions are used to describe the electric elastic state of the sample under research. More accurate correlations designated to describe the application of a high conductivity voltmeter are considered in this paper to identify the difference of potentials between the electrode planes. Numerous analyses of the research results have proven that the conductivity of the measuring device produces a significant influence on the shape and the maximal intensity of the electric impulse. However, the stress-strained state of the cylinder is changed insignificantly. Besides, dependence of oscillations and shapes of the solid piezoceramic cylinder on electric boundary conditions has been analyzed. The influence of the geometric dimensions of the cylinder on the values of the electric field in the piezoceramic material has been the subject of research.

Preliminary Thermography Studies for Quality Control of Concrete Structures Strengthened with Fiber-Reinforced Polymer Composites

Fiber-reinforced polymer (FRP) composites, in the form of pultruded laminates or built-up woven fabrics, are being used widely to strengthen existing concrete and masonry structures. The success of these materials in performing their intended functions depends, to a large extent, on how well they are bonded to themselves and to the substrate. There is a need for an efficient and reliable method to detect and characterize defects at the substrate interface and within multi-ply systems. Infrared thermography is well suited for this purpose because it is inherently sensitive to the presence of near-surface defects and can interrogate large areas efficiently. Before infrared thermography can be developed into a standard methodology, however, an understanding is needed of the effects of testing parameters and different types of defects. A multiyear study is under way to develop this understanding through the use of controlled-flaw experiments and finite-element modeling. This paper reports on the initial phases of this study. An experimental setup is described for measuring the emissivity of a carbon FRP composite and for obtaining a well-defined heat pulse. Good agreement was found between experimental thermal response parameters and those calculated from finite-element models of controlled-flaw specimens. This agreement provides assurance of the validity of parametric studies based on numerical simulations.

시험조건과 고강도콘크리트의 압축강도 관계에 관한 실험적 연구

The strength and durability of concrete are affected by various factors such as the quality of material, mixing ratio, construction, the method of cure, time elapsed. the condition of test and etc., it is very difficult to pre-estimate the strength of concrete with the use of experimental specimen. The domestic standard of specimen cylindrical type and its sizes are both l0cm<TEX>$\times$</TEX>20cm and 15cm<TEX>$\times$</TEX>30cm, which are prescribed in KS F2405, and the loading speed is prescribed to test with 2~3kgf/<TEX>$\textrm{cm}^2$</TEX> per second. The loading speed should have great effect on the compressive strength, but in reality in the construction site sometimes the loading speed is applied so dubiously that the value of the compressive strength can be unreliable. And the cross sectional area of a specimen should be level and smooth, otherwise it can be broken at a lower stress than the real strength through the eccentric or intensive working of the load. Capping should be carried out in order to measure the strength correctly. And used for capping are various materials such as capping compound, cement glue, plaster, mechanical grinding and etc. In this study, therefore, I have carried out an experiment on the relationship among the loading speed, the ratio of height to diameter of specimen, the method of capping, and the compressive strength, for the efficient quality control of concrete structures. So this study has been purposed to provide some basic data that can be used effectively at construction sites.

Diagnostics of reinforced concrete bridges by the acoustic emission (AE) method : Muravin, G.B.; Lezvinskaya, L.M. Quality Control of Concrete Structures, Ghent (Belgium), 12–14 Jun. 1991. pp. 357–365. Edited by L. Taerwe and H. Lambotte. E & FN Spon (1991)

Diagnostics of reinforced concrete bridges by the acoustic emission (AE) method : Muravin, G.B.; Lezvinskaya, L.M. Quality Control of Concrete Structures, Ghent (Belgium), 12–14 Jun. 1991. pp. 357–365. Edited by L. Taerwe and H. Lambotte. E & FN Spon (1991)

Quality control of concrete structures

Quality control of concrete structures