New predictive models to evaluate concrete compressive strength using the SonReb method

Compression strength is the most important factor in concrete structures, and there are two methods to evaluate that compressive strength, destructive and non-destructive method. This work presents a study on the deference and comparison between Destructive (compressive strength test) and a Non-Destructive Method (Rebound Hammer and Ultrasonic test) for testing the compressive strength of concrete.The investigations aimed to develop the method of assessment the strength of concrete of both non-destructive tests with greater accuracy. Destructive method, to determine the strength of the in-situ concrete, and also destructive testing (DT), includes methods where the material is broken down in order to determine its mechanical properties. From the obtained results it is observed that the Rebound Hammer readings increased with the compressive strength of concrete. And the Ultrasonic pulse velocity were greatly influenced by the cements and aggregate, extent of moist curing and presence of flaws and voids in concrete, more than their influence on the measured strengths. This demonstrates the limitation of using ultrasonic pulse velocity tests for estimating compressive strength of concrete. Combined use of Ultrasonic pulse velocity (UPV) and Rebound Hammer tests for assessment of concrete strength in structures with greater reliability.

In the design of new structures, EN 1992‐1‐1 normatively regulates the correlation between the compressive strength and tensile strength of concrete, in accordance with EN 206‐1. However, as there are many time‐ and load‐dependent impacts on existing structures, the relationship described by EN 1992‐1‐1 cannot be assumed without any further observations for existing structures. At the moment, there is no comprehensive investigation on the influences of, for example, subsequent hardening and carbonation on the concrete compressive or tensile strength. The tensile strength of concrete defined in EN 1992‐1‐1 is based on a water storage and a testing age of 28 days. Furthermore, the in‐situ tensile strength is affected by micro‐crack formation cause of internal stresses due to outflow of hydration heat, for example. Generally, there is a different influence of micro‐crack formation on the tensile strength of concrete than on the compressive strength of concrete. The actual value of the in‐situ tensile strength of concrete affects the shear force resistance and the load‐bearing capacity of anchors with concrete cone failure as decisive failure mode. Within the framework of a research project (SWD‐10.08.18.7‐13.01), financed by “Forschungsinitiative Zukunft Bau”, an initiative of the Federal Institute for Research on Building, Urban Affairs and Spatial Development (BBR) structural investigations on the correlation between the compressive and tensile strength of old concretes have been performed. Below, the results of the research project are presented.

Structural health monitoring is an indispensable procedure that is to be carried out to evaluate the serviceability of existing structures. Non-destructive testing methods are attaining increasing popularity for the assessment of concrete strength due to the ease of operation and reliability of the results. The application of machine learning in the field of engineering has increased rampantly. In this study, the compressive strength of concrete has been forecasted using support vector regression which is a machine learning technique. Artificial intelligence is nothing but the potential to impersonate human intelligence. The advantage of artificial intelligence over human intelligence is the absence of human errors that can arise due to various factors which might decrease the accuracy of results. Rebound hammer (RBH), Windsor probe penetration (WPP) and ultra-sonic pulse velocity(USV) are the non-destructive testing that has been employed to assess the concrete compressive strength. The use of multiple non-destructive testing methods than single testing methods has improved the accuracy of prediction model. Further the results of different combination models were compared using coefficient of determination which is a commonly used statistical parameter for prediction accuracy comparison. The prediction model is in accordance with the experimental results obtained. And the accuracy of prediction indicates that support vector regression can be successfully used for predicting the compressive strength of concrete.

Combined Use of Non-Destructive Tests for Assessment of Strength of Concrete in Structure

Using NIRS technique is an elegant and very precise, this technique become more frequently used for determining physico-chemical properties of feed, especially chemical composition (dry matter, protein, ash, fiber, fat, non-nitrogenous extractive substances. The contents of dry matter, crude protein, crude ash, crude fiber, crude fat, non – nitrogenous extractive substances of maize are determined by destructive methods and then using them was build the calibration curve for NIRS with which we will determine all the chemical properties of the material using prediction.
 This paper aims to highlight a way of direct analysis method undestructive of crude protein, crude fat, crude fiber, crude ash, non-nitrogenous extractive substances using near infrared spectrometry technique in conjunction with reflected attenuated total. For each property we have used these method assessment: for the crude protein was used Kjeldahl method, for crude fat was used Soxhlet method, for crude ash performed Hennenberg – Stohmann method, for crude fiber was used Hennenberg - Stohmann method and for non – nitrogenous extractive substances was used mathematical calculation. All these results determined by the classical method, the destructive method, were used to build the calibration curve for device FT-NIR Spectrometer Perkin Elmer Spectrum 100 N with accessory N NIRA. Mathematical model was built using the near infrared spectrofotoscopiei technique in conjunction with multivariable calibration techniques using the Perkin Elmer program Spectrum Quant + 4.60. The method provides a rapid and reliable alternative to traditional quantitative methods for determining which usually requires several hours to complete.

Destructive and non-destructive methods have been used for the determination of microtraces of antimony in high-purity silicon powder. The destructive method was based on substoichiometric radioactivation analysis with solvent extraction using BPHA and cupferron as organic reagents. The antimony contents in high-purity silicon can be determined by the proposed method.

Developing non-destructive methods (NDT) that can deliver faster and more accurate results is an objective pursued by many researchers. The purpose of this paper is to present a new approach in predicting the concrete compressive strength through means of ultrasonic testing for non-destructive determination of the dynamic and static modulus of elasticity. For this study, the dynamic Poisson’s coefficient was assigned values provided by technical literature. Using ultra-sonic pulse velocity (UPV) the apparent density and the dynamic modulus of elasticity were determined. The viability of the theoretical approach proposed by Salman, used for the air-dry density determination (predicted density), was experimentally confirmed (measured density). The calculated accuracy of the Salman method ranged between 98 and 99% for all the four groups of specimens used in the study. Furthermore, the static modulus of elasticity was deducted through a linear relationship between the two moduli of elasticity. Finally, the concrete compressive strength was mathematically determined by using the previously mentioned parameters. The accuracy of the proposed method for concrete compressive strength assessment ranged between 92 and 94%. The precision was established with respect to the destructive testing of concrete cores. For this research, the experimental part was performed on concrete cores extracted from different elements of different structures and divided into four distinct groups. The high rate of accuracy in predicting the concrete compressive strength, provided by this study, exceeds 90% with respect to the reference, and makes this method suitable for further investigations related to both the optimization of the procedure and = the domain of applicability (in terms of structural aspects and concrete mix design, environmental conditions, etc.).

Concrete is the most important building material of our century. Concrete, which works under compression, is a brittle material with a low tensile strength. The addition of various types of fibers to concrete increases its ductility. Basically, the use of fibers is intended to increase crack control and ductility. Today, the use of various fibers is becoming widespread. It may be necessary from time to time to reassess and evaluate newly completed reinforced concrete buildings or those buildings still under construction as well as those in existence for years. The concrete strength of a building can be determined by using non-destructive methods or by taking cores. It is an inevitable necessity that the number of cores be limited because taking cores may lead to a weakening of the structural members. The aim of this study is to compare the mechanical properties of concrete with steel fiber, polypropylene fiber and with both in combination and to investigate the effects of using these fibers on the mechanical properties of concrete. Another objective of the study is to compare concrete compressive strength as determined by the destructive method with that determined by a non-destructive method.

Rice wastes are rich of silica content.It is subjected to an acid chemical treatment, followed by the sol-gel process, and then it is burned in an electric muffle furnace at a temperature of 600 degrees Celsius.This produced silica nanoparticles.The inorganic contaminants in the rice husk ash were purified by leaching them with Hydrochloric acid, boiling them between 80 and 85 degrees Celsius, and then washing them till the PH value reached the neutral limit of 7. The methods involved in preparing the nano-silica (NS) samples were carried out in somewhat different ways for each of the three samples.X-ray diffraction (XRD), energydispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) were used in order to evaluate each specimen in terms of its level of purity and the size of its individual particles.In addition, the three samples were added to concrete mix at 2% of the total binder content as an addition.The compressive strengths of these concretes were then assessed at 7 and 28 days of age and compared with the compressive strengths of normal and silica fume concretes.In addition, the performance of an NS sample with greater purity, smaller particle size, and better responsiveness in concrete was compared to that of commercial NS.It was discovered that the NS can be made at a price and with qualities comparable to those of commercially available NS, which were deemed to be fair.Additionally, the influence of locally manufactured NS on the strength of the concrete was shown to be more evident than the effect of commercially produced NS.

The rise in paper waste from the paper processing sector is becoming the most important issue of disposal by filling large space and polluting the atmosphere, as it rises day to day. To decrease the paper waste as well as environmental emissions, it is recommended to use the paper waste in concrete as Hypo sludge. That contains the properties of cement such as SiO2 & Mg. Cement is the predominant material in concrete. In this research cement is replaced with fly ash as well as hypo sludge. By adding 5percent of fly ash and 0%, 3 %, 6%,9%,12% and 15% of hypo sludge, split tensile strength & compressive strength of concrete as well as Hypo sludge concrete efficiency are being tested. Split tensile strength & compressive strength of hypo sludge concrete are improved by the experiment up to 9% behind this % strength will decrease. In this journal the extension of research work is added that is flexural strength of concrete adding fly ash & hypo sludge in concrete and durability of concrete are studied. Performance of hypo sludge concrete, result and optimum percentage are mentioned in this paper.

Destructive methods are commonly used to evaluate residual stresses in a wide range of engineering components. While seemingly less attractive than non-destructive methods because of the specimen damage they cause, the non-destructive methods are very frequently the preferred choice because of their versatility and reliability. Many different methods and variations of methods have been developed to suit various specimen geometries and measurement objectives. Previously, only specimens with simple geometries could be handled, now the availability of sophisticated computational tools and of high-precision machining and measurement processes have greatly expanded the scope of the destructive methods for residual stress evaluation. This paper reviews several prominent destructive measurement methods, describes recent advances, and indicates some promising directions for future developments.

Contrast-enhanced ultrasound has shown convincing results for monitoring vessel morphology, surrogate markers of vascularization and changes in molecular marker expression in oncological and cardiovascular diseases. Ultrasound contrast agents have the ability to increase the backscattering signal intensity of an ultrasound pulse. An interesting class of ultrasound contrast agents are gas filled microbubbles, which can be synthesized by external bubble encapsulation using sugar matrices or microspheres consisting of lipids or polymers with or without surfactant and by selecting gases with low blood solubility and diffusion coefficient such as perfluorocarbons or sulphur hexafluoride. Ultrasound contrast agents can be classified according to the rigidity of their shell. Soft-shell microbubbles are coated with a thin monolayer of surfactant molecules such as palmitic acid or phospholipids and are very sensitive to pressure changes. Hard-shell microbubbles have a rigid shell made of polymers such as polycyanoacrylate, which dramatically increases their stability. Depending on the acoustic properties of the microbubbles and on the purpose of the examination either destructive or non destructive methods are preferred for their detection. Microbubbles can be detected by destructive and non-destructive methods. Both soft- and hard-shell microbubbles coated with target-specific molecules can also be used for molecular imaging. Using target-specific approaches, the expression of several angiogenic markers such as VEGFR2, alphavbeta3 Integrins, ICAM, and E-selectin has been investigated in neoplastic and vascular diseases. This article summarizes the synthesis and properties of contrast agents as well as the indications, limitations and future potential of contrast-enhanced functional and molecular ultrasound.

Analysis of the accuracy of in-situ concrete characteristic compressive strength assessment in real structures using destructive and non-destructive testing methods

In the course of research, the efficiency of application of plasticizers of different type in concretes for bases of highways on secondary crushed stone is defined. In studies of concrete compositions, the type of crushed stone, secondary or granite, changed, which allowed to compare the properties of concrete on secondary crushed stone with the properties of concrete of similar composition on granite crushed stone. In addition, the type of sand changed: Bilyaevsky or Voznesenski quarry. As modifiers used additive lignosulfonate or superplasticizer polycarboxylate type MC-PowerFlow 3200. All concrete mixtures had equal mobility P2, which was provided by variation W/C (water-cement ratio). It was found that the concrete on the secondary crushed stone is characterized by a significantly higher W/C mixture due to greater porosity and damage to the surface of the coarse aggregate. The average density of concrete on secondary crushed stone is 4.2-4.4% lower compared to the average density of concrete on granite crushed stone. The average density of concrete on the larger sand of the Voznesenski quarry is 25-30 kg/m3 higher than the average density of concrete on similar gravel and finer sand of the Bilyaevsky quarry. In composites based on CEM III/A and using lingosulfonate additives, the compressive strength of concrete on secondary crushed stone is 12-13% lower compared to the strength of concrete on granite crushed stone and similar sand. However, when using the more efficient MC-PowerFlow 3200 additive, the difference in concrete strength on secondary and granite crushed stone is only 5.4% (29.8 MPa and 31.4 MPa, respectively). The strength of concrete on the sand of the Voznesenski quarry is 4-6% higher than the strength of concrete on similar gravel and finer sand of the Bilyaevsky quarry. It was found that the tensile strength when bending concrete on secondary and granite gravel when using the additive MC-PowerFlow 3200 was 2.75 MPa and 2.87 MPa, respectively, which differs by only 4%. Thus, the tensile strength of bending concrete on secondary crushed stone was almost no different from the tensile strength of similar concrete on granite crushed stone. This can be explained by the peculiarities of the aggregate with a porous surface, which is characterized by high adhesion to the cement-sand matrix. In general, the strength of concrete on secondary crushed stone using slag-containing cements allows them to be used effectively for road bases.

Deep learning based concrete compressive strength prediction model with hybrid meta-heuristic approach