Journal articles: 'Rebound hammer test'

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Wang, Yu Ren, Dai Lun Chiang, and Yi Jao Chen. "Adapting ANFIS to Improve Field Rebound Hammer Test for Concrete Compressive Strength Estimation." Materials Science Forum 975 (January 2020): 191–96. http://dx.doi.org/10.4028/www.scientific.net/msf.975.191.

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Rebound hammer tests are one of the most popular non-destructive testing methods to examine the concrete compressive strength in the field. Rebound hammer tests are relatively easy to conduct and low cost. More importantly, it will not cause damage to the existing structure and can obtain the results in a short time. However, concrete compressive strength estimations provided by rebound hammer tests have an average of around 20% mean absolute percentage error (MAPE) when comparing to the results from destructive tests. This research proposes an alternative approach to estimate the concrete compressive strengths using the rebound hammer test data. The alternative approach is to adopt the Artificial Neural Fuzzy Inference Systems, ANFIS, to develop an AI-based prediction model for the rebound hammer tests. A total of 100 rebound hammer tests are conducted in a 24-story residential building. Core samples are carefully taken to obtain the actual compressive tests. The data collected are used to train and validate the ANFIS prediction model. The results show that the proposed ANFIS model has successfully reduced the MAPE to 10.01%.

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Deng, Peng, Yan Sun, Yan Liu, and Xiaoxiao Song. "Revised Rebound Hammer and Pull-Out Test Strength Curves for Fiber-Reinforced Concrete." Advances in Civil Engineering 2020 (February 24, 2020): 1–12. http://dx.doi.org/10.1155/2020/8263745.

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Rebound hammer tests and postinstalled pull-out tests are commonly used for evaluating the compressive strength of ordinary concrete, and the strength of concrete is estimated by strength curves. However, using these strength curves to predict the compressive strength of carbon fiber-reinforced concrete (CFRC), polypropylene fiber-reinforced concrete (PFRC), and carbon-polypropylene hybrid fiber-reinforced concrete (HFRC) may lead to considerable uncertainties. Therefore, this study revises the strength curves derived from rebound hammer tests and postinstalled pull-out tests for ordinary concrete. 480 specimens of fiber-reinforced concrete (FRC) of six strength grades are examined. Standard cube compressive strength tests are used as a reference, and the results of various regression models are compared. The linear model is determined as the most accurate model for postinstalled pull-out tests, whereas the power model is the most accurate for rebound hammer tests. The proposed strength curves have important applications for FRC engineering of the postinstalled pull-out tests and rebound hammer tests.

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Wang, Yu Ren, Wen Ten Kuo, Shian Shien Lu, Yi Fan Shih, and Shih Shian Wei. "Applying Support Vector Machines in Rebound Hammer Test." Advanced Materials Research 853 (December 2013): 600–604. http://dx.doi.org/10.4028/www.scientific.net/amr.853.600.

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There are several nondestructive testing techniques available to test the compressive strength of the concrete and the Rebound Hammer Test is among one of the fast and economical methods. Nevertheless, it is found that the prediction results from Rebound Hammer Test are not satisfying (over 20% mean absolute percentage error). In view of this, this research intends to develop a concrete compressive strength prediction model for the SilverSchmidt test hammer, using data collected from 838 lab tests. The Q-values yield from the concrete test hammer SilverSchmidt is set as the input variable and the concrete compressive strength is set as the output variable for the prediction model. For the non-linear relationships, artificial intelligence technique, Support Vector Machines (SVMs), are adopted to develop the prediction models. The results show that the mean absolute percentage errors for SVMs prediction model, 6.76%, improves a lot when comparing to SilverSchmidt predictions. It is recommended that the artificial intelligence prediction models can be applied in the SilverSchmidt tests to improve the prediction accuracy.

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Jarushi, Fauzi, Paul J. Cosentino, and Edward H. Kalajian. "Prediction of High Pile Rebound with Fines Content and Uncorrected Blow Counts from Standard Penetration Test." Transportation Research Record: Journal of the Transportation Research Board 2363, no. 1 (January 2013): 47–55. http://dx.doi.org/10.3141/2363-06.

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High-displacement piles have rebounded significantly while undergoing an extremely small permanent set per hammer blow in certain soils. This phenomenon, called high pile rebound (HPR), has occurred in many areas of North America. The Florida Department of Transportation identified HPR at six sites in Florida during the process of driving square, precast, prestressed concrete piles into saturated, fine silty-to-clayey sand and sandy-clay soils. Data on pile driving analyzer deflection versus time were used to develop strong correlations between fines content, uncorrected standard penetration test blow counts (NSPT), pile displacements, and rebound. The correlations developed in this study allow the geotechnical engineer to predict whether HPR will occur at a proposed site at which high-displacement piles are planned for driving by a single-acting diesel hammer. A design equation relating pile rebound to NSPT and fines content was developed. The correlations showed that permanent set and rebound were a direct function of NSPT and fines content of the soil at the pile tip. The design equation provides a methodology that allows prediction of HPR during the design phase.

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Bui, Quoc-Bao. "Assessing the Rebound Hammer Test for Rammed Earth Material." Sustainability 9, no. 10 (October 21, 2017): 1904. http://dx.doi.org/10.3390/su9101904.

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Brencich, Antonio, Giancarlo Cassini, Davide Pera, and Giuseppe Riotto. "Calibration and Reliability of the Rebound (Schmidt) Hammer Test." Civil Engineering and Architecture 1, no. 3 (October 2013): 66–78. http://dx.doi.org/10.13189/cea.2013.010303.

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Brožovský, Jiří. "Influence of Moisture of Light-Weight Concrete Containing Lightweight Expanded Clay Aggregate on Test Results Obtained by Means of Impact Hammer." Advanced Materials Research 753-755 (August 2013): 663–67. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.663.

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Properties of light-weight concrete congaing lightweight expanded clay aggregate differ from the ones of normal-weight concrete containing natural normal-weight aggregate. Particularly, when compared with natural normal-weight aggregate, these differences are due to lightweight aggregate being characterized by significantly lower strength and bulk weight as well as higher absorptivity. Properties of expanded clay lightweight aggregate influence the ones of light-weight concrete, too. Parameters obtained by means of Schmidt impact hammer non-destructive testing are influenced by series of factors, among others also concrete moisture. Moisture of light-weight concrete containing lightweight aggregate influences rebound number of Schmidt impact hammer. As to Schmidt impact hammer type N (2.25 Nm impact energy), rebound number on dry concrete exceeds the one on waterlogged concrete by 21 %. Correction coefficients for rebound number correction were defined taking into account moisture of light-weight concrete under testing.

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Borosnyói, Adorján, and Katalin Szilágyi. "Studies on the spatial variability of rebound hammer test results recorded at in-situ testing." Epitoanyag - Journal of Silicate Based and Composite Materials 65, no. 4 (2013): 102–6. http://dx.doi.org/10.14382/epitoanyag-jsbcm.2013.19.

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Brožovský, Jiří. "Rebound Hammer Tests of Calcium Silicate Bricks – Effects of Internal Compressive Stress on Measurement Results." Applied Mechanics and Materials 595 (July 2014): 155–58. http://dx.doi.org/10.4028/www.scientific.net/amm.595.155.

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The rebound hammers of the Schmidt system belong among the non-destructive testing methods that are used for determining compressive strength of building materials, most often concrete and rocks. Calibration relations between the rebound number and compressive strength must be available to determine the compressive strength. Calibration relations are determined on the basis of destructive and non-destructive tests of test specimens. This paper deals with the effects of internal compressive stress in calcium silicate bricks on measurement results obtained using the L-type Schmidt hammer. Based on the obtained information, in order to process calibration relations, it is recommended to apply such force to the test specimens, which corresponds to the internal compressive stress 10-15% of the final compressive strength. We do not recommend measuring on firmly supported bricks only.

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Kongola, Moses, and Karim Baruti. "Prediction of Uniaxial Compressive Strength of Granite Rock Samples of Lugoba Quarry Using Rebound Hammer Test." Tanzania Journal of Engineering and Technology 40, no. 1 (July 31, 2021): 16–27. http://dx.doi.org/10.52339/tjet.v40i1.710.

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Rebound hammer test is widely used as an indirect measure of uniaxial compressive strength for engineering materials such as concrete, soil, and rock in both civil and mining engineering works. In quarries, uniaxial compressive strength is a crucial parameter in the analysis of geotechnical problems involving rock stability and rock blasting design. This study aims at establishing the empirical models of uniaxial compressive strength fits on rebound hammer number that can be used to predict uniaxial compressive strength of granitic rock at Lugoba Quarry. Data for direct uniaxial compressive strength were obtained from uniaxial compressive strength test carried out on 20 core samples at the Dar es Salaam Institute of Technology Geotechnical Laboratory using ISMR Standard Procedures. The rebound hammer test was carried out using testing hammer type N. The tests were done horizontally on two scanline's geotechnical domains of the rock mass on the footwall side of the quarry. The obtained results of UCS ranging from 105 to 132.5 MPa and RHN from 44.90 to 49.5 were found to be comparable with values of other granitic rocks in other parts of the world. Regression Analysis using SPSS software was carried out to develop 5 regression models of UCS vs.RHN. The values of obtained in this study were found to be between 0.93 and 0.95, which are comparable with other studies. This implies that RHN accounted between 93 and 95% of the total variation of the UCS and the relationships were very strong. Two models; Logarithmic and exponential were found to be appropriate and recommended for application at Lugoba Quarry.

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Onyeka, Festus Chukwudi. "A Comparative Analysis of the Rebound Hammer and Pullout as Non-Destructive Method in Testing Concrete." European Journal of Engineering Research and Science 5, no. 5 (May 12, 2020): 554–58. http://dx.doi.org/10.24018/ejers.2020.5.5.1903.

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A comparative analysis between Rebound Hammer and Pullout method in testing concrete was conducted in this study. Experimental analysis were carried out to compare the correctness between the two testing method in estimating the strength of concrete. Different cube (cubes of 175 x 175 x 175) samples were prepared using two mix designs of 1:2:4 and 1:3:6 with a constant w/c ratio of 0.45 and were tested at 7, 14, 21 and 28 days. The rebound hammer readings had a correlation coefficient of 0.695 while the pullout had a correlation coefficient of 0.725 for the 1:2:4 mix and the rebound hammer readings for 1:3:6 was 0.724 and that for the pullout was 0.675. From the results obtained, it is observed that the non-destructive testing methods were correlated with the compressive strength results which showed that a higher correlation existed between the Rebound Hammer and the compressive strength than the Pullout. Statistical analysis of the results obtained showed that there was no significant difference between the means of the two methods for both mix at a 0.05 level of significance. However, Rebound hammer method can be recommended as it provides a quicker, less-expensive means of checking the uniformity of concrete even though it shows less sensitivity as concrete matures, unlike the Pullout test in which measuring strength is affected by the arrangement of the embedded insert, the dimensions of bearing ring, the depth of embedment, the concrete age and the type of aggregates uses in concrete.

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Goh, Thian Lai, Nur Amanina Mazlan, Mohd Shahrul Mohd Nadzir, Abdul Ghani Rafek, Ailie Sofyiana Serasa, Azimah Hussin, Khai Ern Lee, and Swee Yeok Foong. "Uniaxial Compressive Strength of Antarctic Peninsula Rocks: Schmidt Hammer Rebound Test." Sains Malaysiana 46, no. 5 (May 31, 2017): 677–84. http://dx.doi.org/10.17576/jsm-2017-4605-01.

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Panedpojaman, Pattamad, and Danupon Tonnayopas. "Rebound hammer test to estimate compressive strength of heat exposed concrete." Construction and Building Materials 172 (May 2018): 387–95. http://dx.doi.org/10.1016/j.conbuildmat.2018.03.179.

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Brožovský, Jiří. "Implementation of Non-Destructive Impact Hammer Testing Methods in Determination of Brick Strength." Applied Mechanics and Materials 174-177 (May 2012): 280–85. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.280.

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In the building industry, non-destructive testing methods are mostly used to determine parameters of concrete structures and concrete of its own; as to other materials, these methods serve semi-occasionally and, as a rule, testing procedures and evaluation are not codified in technical standards. One of non-destructive testing field of applications is testing of piece bricks. This paper deals with findings concerning non-destructive testing of clay solid bricks, honeycomb bricks and lime sand bricks by means of Schmidt Impact Hammers types LB/L. Described here are testing method, procedures of test finding evaluation as well as calibration correlations between impact hammer rebound number and compression strength or flexural strength (lime sand bricks only). Evaluated calibration correlations between impact hammer rebound number and brick strength feature close correlation; its coefficient varies between 0.95 and 0.98, therefore these values are usable in practice. When testing honeycomb bricks varying in hole arrangement and wall thickness, it is necessary to take both these factors into account through specification of calibration correlation of non-destructive/destructive tests of limited number of bricks.

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Pereira, E., and M. H. F. de Medeiros. "Pull Off test to evaluate the compressive strength of concrete: an alternative to Brazilian standard techniques." Revista IBRACON de Estruturas e Materiais 5, no. 6 (December 2012): 757–80. http://dx.doi.org/10.1590/s1983-41952012000600003.

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To estimate the compressive strength of concrete is necessary in many reinforced concrete structures inspection works. In Brazil, the standard tests for this purpose are: Compressive test in drilled cores, rebound hammer test and ultrasonic test. In the United States and Europe are also regulated other techniques. The aim of this paper is to analyze the use of Pull Off test as an inspection tool of concrete and also disclose the possibility of use of complementary techniques to the standard ones in Brazil. The results show that the Pull Off test results in high correlation (R²> 0.93) with the compressive strength, measured in cylindrical and prismatic specimens. The rebound hammer test did not show satisfactory correlation (R²≅0.6) for the case of cylindrical specimens. The ultrasonic test showed high correlation (R²> 0.98), but behaves differently with the shape changing of the specimens.

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Spalvier, Agustin, Kerry Hall, and John S. Popovics. "Comparative Study of Rebound Hammer, Nitto Hammer, and Pullout Tests to Estimate Concrete In-Place Strength by Using Random Sampling Analysis." Transportation Research Record: Journal of the Transportation Research Board 2629, no. 1 (January 2017): 104–11. http://dx.doi.org/10.3141/2629-13.

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The use of nondestructive testing (NDT) techniques to estimate concrete in-place strength has been broadly studied, with proof of their usefulness in complementing destructive testing (DT). However, the use of DT techniques still dominates. The main objective of this investigation was to compare the performance of three NDT techniques—the rebound hammer, Nitto hammer, and pullout tests—to determine in-place strength. NDT-versus-strength correlation curves were fit to data measured from thick concrete slabs. Strength was measured from cast-in-place cylinders. Analyses of NDT sensitivity, uncertainty, and variability are presented. A new parameter to quantify the performance of the NDT techniques is proposed. This parameter is the limit error between the measured and estimated strengths, which combine uncertainty and variability analyses. The analysis shows that the least limit error for predicting in-place strength was achieved by the rebound hammer test when one testing location was considered or by the pullout test for two or more testing locations.

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Eze, E. O., and S. O. Osuji. "Use of Schmidt Hardness Values in Rock Strength Prediction." International Journal of Engineering Research in Africa 11 (October 2013): 73–81. http://dx.doi.org/10.4028/www.scientific.net/jera.11.73.

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Two coarse-grained granitic rocks - charnockite and biotite granite were studied with the aim of estimating their unconfined compressive strength from simpler non-destructive test values. The simpler tests were the ultrasonic pulse velocity, the Schmidt hammer rebound, and the specific gravity. Another test carried out was the moisture absorption. The rocks had compressive strength in the range 115-250 MPa, Schmidt hammer rebound number or index of 35-55, and pulse velocity of 3.4-5.5 km/s. The correlation coefficients between the uniaxial compressive strength and the rebound number were 0.86 and 0.81 for the biotite granite and the charnockite, respectively. Products of the rebound index and the pulse velocity and the specific gravity improved the correlation coefficients to 0.94 and 0.91 respectively. The high correlation factors implied that the compressive strength can be estimated using the simpler tests parameters. These simpler parameters also relate indirectly to geomechanical properties of the rocks such as drillability, boreability and machine tool wear. The moisture absorption alone and its combination with the rebound number correlated inversely and poorly with the compressive strength. The correlation coefficient ranged between 0.45 to 0.67. The moisture absorption therefore proved to be a poor predictor of the uniaxial compressive strength of the rocks.

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Misák, Petr, Dalibor Kocáb, and Petr Cikrle. "Determination of a Suitable Moment for Formwork Removal from a Concrete Structure Using Rebound Hammer Test Methods." Solid State Phenomena 322 (August 9, 2021): 23–27. http://dx.doi.org/10.4028/www.scientific.net/ssp.322.23.

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Determining the compressive strength of concrete in the early stages of ageing has been an increasingly relevant topic in recent years, particularly with regard to the safe removal of formwork from a structure or its part. The compressive strength of concrete which designates safe removal of formwork without damaging the structure can be referred to as "stripping strength". It is undoubtedly beneficial to be able to determine the moment of safe formwork removal in a non-destructive manner, i.e. without compromising the structure. Modern rebound hammer test methods seem to be a suitable instrument with which it is possible to reduce the length of technological breaks associated with concrete ageing to a minimum, and consequently, reduce the total cost of the construction. However, the use of these methods presents a number of challenges. As many conducted experiments have shown, there is no single conversion relationship (regression model) between non-destructive rebound hammer test methods and compressive strength. It is therefore advisable to always create a unique conversion relationship for each individual concrete. In addition, it must be noted that conventional regression analysis methods operate with 50% reliability. In construction testing, however, the most common is the so-called characteristic value, which is defined as a 5% quantile. This value is therefore determined with 95% reliability. This paper describes the construction of a so-called "characteristic curve", which can be used to estimate the compressive strength of concrete in a structure using rebound hammer test methods with 95% reliability. Consequently, the values obtained from the characteristic curve can be easily used for practical applications.

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Gupta, Prof A. R. "To Study the Rebound Hammer Test for Non-Destructive Testing of Structure." International Journal for Research in Applied Science and Engineering Technology 7, no. 5 (May 31, 2019): 3189–96. http://dx.doi.org/10.22214/ijraset.2019.5526.

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Irfan, M. Α., and F. A. Almufadi. "Investigation of Mechanical Properties of Shale Rock in Qassim Region, Saudi Arabia." Engineering, Technology & Applied Science Research 9, no. 1 (February 16, 2019): 3696–98. http://dx.doi.org/10.48084/etasr.2468.

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An investigation into the mechanical properties of shale rock from Qassim Province, Saudi Arabia is presented in this paper. Uniaxial compression test, Schmidt hammer test and porosity estimation were carried out. Regarding the compression test, it was found that the strength ranged from 1.98MPa to 8MPa and the strain ranged from 0.53% to 2.5%. Regarding the Schmidt Hammer test, it was found that the rebound values ranged from 22.4 to 25. The measurements of volumetric porosity indicated that the porosity in the shale rock ranged between 19.12% and 24.31%. All the values determined in this project match well with the published values of other studies about shale rock.

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Zhang, Jin Yang, and Xiu Gao. "The Hollowing Test Method Research in Constructional Floor and Decoration Projects." Applied Mechanics and Materials 178-181 (May 2012): 284–87. http://dx.doi.org/10.4028/www.scientific.net/amm.178-181.284.

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The constructional decoration and constructional flooring projects are the important parts in constructional engineering and currently the qualities of face tile attachment and plaster layer adhering are checked by means of visual observation and gentle knocking with small hammer after the end of project. However, the said conventional visual observation and knocking test methods are more in subjective randomness and low in efficiency to result in poor inspection effect. With the principle of the rebound value being abnormally quite low in case there are air holes or hollowing in the process of compressive strength test of materials with rebound method, the hollowing defect distributions in constructional flooring and architectural decoration engineering can be detected completely, accurately and visually by means of reasonable test point layout and effective defaults judgments.

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Ahn, Hyo-Soo, and Chee-Ho Seo. "An Experimental Study on the Rebound Degree Tendency of Linear Hitting Test Hammer." Journal of the Korea Concrete Institute 17, no. 3 (June 1, 2005): 313–22. http://dx.doi.org/10.4334/jkci.2005.17.3.313.

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Brozovsky, Jiri. "High-strength concrete – NDT with rebound hammer: influence of aggregate on test results." Nondestructive Testing and Evaluation 29, no. 3 (June 16, 2014): 255–68. http://dx.doi.org/10.1080/10589759.2014.926897.

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Brencich, Antonio, Rossella Bovolenta, Valeria Ghiggi, Davide Pera, and Paolo Redaelli. "Rebound Hammer Test: An Investigation into Its Reliability in Applications on Concrete Structures." Advances in Materials Science and Engineering 2020 (December 14, 2020): 1–11. http://dx.doi.org/10.1155/2020/6450183.

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The issue of concrete strength often arises in civil engineering practice, either due to quality control of new constructions or due to the assessment of existing structures. To this aim, one of the most widely spread techniques is the rebound hammer (Schmidt hammer) test, for which calibration is still related to the original Schmidt curve dating back to the early 50’s. In spite of the large amount of research work performed in the last decades, the uncertainties of the rebound test are still not clearly quantified and open to further insight. This paper presents and discusses a wide research campaign on laboratory specimens and on third-party specimens delivered to the Laboratory for Building Materials of the University of Genoa, Italy, for standard quality controls. While it is well known that moisture content, surface finishing, and concrete maturity strongly affect the test result, the effect of the stress state has not yet been studied and is found in this research to be a further parameter affecting the test reliability. The final outcome of all the uncertainties is variability in estimated concrete strength as large as ±70%; additionally, some issues are discussed on the intrinsic uncertainty of this test. As already demonstrated by many authors, the results of this research also show that a universal calibration curve to be used for any concrete, in any condition, conceptually does not exist.

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Scanlon, Andrew, and Leonid Mikhailovsky. "Strength evaluation of an existing concrete bridge based on core and non-destructive test data." Canadian Journal of Civil Engineering 14, no. 2 (April 1, 1987): 145–54. http://dx.doi.org/10.1139/l87-026.

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The use of concrete cores and nondestructive testing for strength evaluation of existing structures is illustrated through an evaluation of an existing concrete bridge. The results confirm that rebound hammer number should not be used alone as an indicator of in situ compressive strength. Reasonably good correlation is demonstrated between pulse velocity and compressive strength, with a slight improvement when pulse velocity and rebound number are combined.A probabilistic approach to structural evaluation of existing structures is proposed in which the variability of in situ concrete compression strength and uncertainty associated with indirect nondestructive testing are incorporated. An example of shear strength evaluation is given, which indicates a range of increase in shear strength compared with initial design parameters of 17–37% depending on the amount and type of data available.

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Cikrle, P., D. Kocab, and P. Misak. "Experimental determination of the initial compressive strength of concrete using a rebound test hammer." IOP Conference Series: Materials Science and Engineering 385 (July 2018): 012008. http://dx.doi.org/10.1088/1757-899x/385/1/012008.

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Holčapek, Ondřej, Jiří Litoš, and Jan Zatloukal. "Destructive and Nondestructive Characteristics of Old Concrete." Advanced Materials Research 1054 (October 2014): 243–47. http://dx.doi.org/10.4028/www.scientific.net/amr.1054.243.

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This paper aims at determination of mechanical properties of 28 years old concrete with various nondestructive and destructive testing methods. All investigated parameters were determined on drilled cores with diameter 79.8 mm gained from existing bridge. On these samples Schmidt rebound testing and destructive force loading test were performed. Static (from loading test) and dynamic (measured by ultrasonic device) modulus of elasticity was also measured. The evaluation of destructive and nondestructive testing was according to the Czech Standards. Testing of old concrete from real structures is important especially prior to the reconstruction, strengthening or repair of the structure, when the structural engineer needs to know the characteristics. The compressive strength measured destructively on cylinders achieved average value 28 MPa, while the Schmidt rebound hammer test showed strength 44 MPa. The average value of static modulus of elasticity was 26 GPa.

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Xu, Taozhi, and Jie Li. "Assessing the spatial variability of the concrete by the rebound hammer test and compression test of drilled cores." Construction and Building Materials 188 (November 2018): 820–32. http://dx.doi.org/10.1016/j.conbuildmat.2018.08.138.

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Retno Susilorini, Rr M. I., Rina Febrina, and Helmia Adita Fitra. "Evaluating Couple Simple Shear Wall as Low-cost Masonry Wall Strengthening by Rebound Hammer Test." International Journal of Engineering Research and Technology 13, no. 3 (March 30, 2020): 600. http://dx.doi.org/10.37624/ijert/13.3.2020.600-607.

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Loche, Marco, Gianvito Scaringi, Jan Blahůt, Maria Melis, Antonio Funedda, Stefania Da Pelo, Ivan Erbì, Giacomo Deiana, Mattia Meloni, and Fabrizio Cocco. "An Infrared Thermography Approach to Evaluate the Strength of a Rock Cliff." Remote Sensing 13, no. 7 (March 26, 2021): 1265. http://dx.doi.org/10.3390/rs13071265.

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The mechanical strength is a fundamental characteristic of rock masses that can be empirically related to a number of properties and to the likelihood of instability phenomena. Direct field acquisition of mechanical information on tall cliffs, however, is challenging, particularly in coastal and alpine environments. Here, we propose a method to evaluate the compressive strength of rock blocks by monitoring their thermal behaviour over a 24-h period by infrared thermography. Using a drone-mounted thermal camera and a Schmidt (rebound) hammer, we surveyed granitoid and aphanitic blocks in a coastal cliff in south-east Sardinia, Italy. We observed a strong correlation between a simple cooling index, evaluated in the hours succeeding the temperature peak, and strength values estimated from rebound hammer test results. We also noticed different heating-cooling patterns in relation to the nature and structure of the rock blocks and to the size of the fractures. Although further validation is warranted in different morpho-lithological settings, we believe the proposed method may prove a valid tool for the characterisation of non-directly accessible rock faces, and may serve as a basis for the formulation, calibration, and validation of thermo-hydro-mechanical constitutive models.

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Carasek, Helena, Fernando Henrique Vaz, and Oswaldo Cascudo. "Statistical analysis of test methods to evaluate rendering surface properties." Ambiente Construído 18, no. 2 (April 2018): 87–105. http://dx.doi.org/10.1590/s1678-86212018000200244.

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Abstract The objective of this study is to discuss the results of two test methods used to evaluate rendering surface properties: the superficial tensile strength (STS) and the pendulum rebound hammer (which provides the rebound index - RI), besides evaluating, additionally, the tensile bond strength (BS). The studied variables were the type of mortar (job-site mortar and dry-mix mortar) and the render moisture at the time of testing (in four contents). For each test, a minimum of 45 determinations was planned per analyzed situation, totaling 1411 valid results, which allowed a consistent statistical analysis and an in-depth discussion of the methods. The STS and RI tests were sensitive at a 95% confidence level to differentiate mortars from different strengths and were therefore approved for this evaluation. The most significant effect in all statistical models tested was the type of mortar. The variable moisture condition of the render was significant only for the results of STS and BS. In such cases, tests performed with wet or saturated renders presented much lower strength results compared to those carried out with air- dried renders. It was possible to obtain a significant correlation between STS and BS, with a high coefficient of determination.

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Wang, Yu Ren, Loan T. Q. Ngo, Yi Fan Shih, Yen Ling Lu, and Yi Ming Chen. "Adapting ANNs in SONREB Test to Estimate Concrete Compressive Strength." Key Engineering Materials 792 (December 2018): 166–69. http://dx.doi.org/10.4028/www.scientific.net/kem.792.166.

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SONREB method is a non-destructive testing (NDT) method for estimating the concrete compressive strength. It is conducted by combining two popular NDT methods: ultrasonic pulse velocity (UPV) test and rebound hammer (RH) test. Several researches have been attempted to find the correlation of the different testing method data with actual compressive strength. This research proposes a new Artificial Intelligence based approach, Artificial Neural Networks (ANNs), to estimate the concrete compressive strength using the UPV and RH test data. Data from a total of 315 cylinder concrete samples are collected to develop and validate the ANFIS prediction model. The model prediction results are compared with actual compressive strength using mean absolute percentage error (MAPE). With the adaption of ANFIS, the estimation error of SONREB test can be reduced to 5.98% (measured by MAPE).

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Halimi, Behrouz, Hamidreza Saba, Saeid Jafari MehrAbadi, and Saeid Saeidi Jam. "Laboratory study and measurement of stiffness and compaction of unsaturated clay soil by using the innovative rebound hammer." Nexo Revista Científica 34, no. 02 (June 7, 2021): 710–32. http://dx.doi.org/10.5377/nexo.v34i02.11557.

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Defining soil behavioral parameters, which eventually results in predicting every short-term and long-term soil behavior, has continually been one of the interests of soil mechanics and has been of exceptional value. To this end, in this study, a novel method has been reviewed to determine the compressive behavior of fine-grained soils in the laboratory and the field, without sampling by the patented electronic device. In the lab, homogeneous materials of the intended soil underwent the compaction test, mechanical and physical tests, direct shear test, and impacts of the innovative rebound hammer in the horizontal and vertical directions in the test-box. The impact shear waves produce resistance and voltage output by force and dislocation sensors with high-sensitivity proportional to the pressure based on the soil surface stiffness. The obtained voltages are then converted to digital by an analog-to-digital converter and a microcontroller. Next, a number is shown on display by the "CodeVision" program. Then, by solving a quasi-dynamic equation (Viscoelastic spring-damper model) by MATLAB software and with the aid of laboratory-field results and correlation equations, a fitting connection between all effective mechanical soil parameters has been estimated to an acceptable extent. The effective mechanical parameters of the soil include the compaction percentage, specific gravity, and frequency of the system in the damped and non-damped states, the energy imposed on the soil, and the plastic stage strain in the range of less than 15% humidity. The results determine that increased hammering numbers are directly related to increased soil compaction and stiffness. In more detail, the reading of hammer numbers less than 2 corresponds to compaction of less than 75%, while the reading of hammer numbers greater than 3 in the vertical and 2.94 in the horizontal directions on clay surfaces designates compaction of 90%.

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Kocáb, Dalibor, Petr Misák, and Petr Cikrle. "Characteristic Curve and Its Use in Determining the Compressive Strength of Concrete by the Rebound Hammer Test." Materials 12, no. 17 (August 23, 2019): 2705. http://dx.doi.org/10.3390/ma12172705.

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During the construction of concrete structures, it is often useful to know compressive strength at an early age. This is an amount of strength required for the safe removal of formwork, also known as stripping strength. It is certainly helpful to determine this strength non-destructively, i.e., without any invasive steps that would damage the structure. Second only to the ultrasonic pulse velocity test, the rebound hammer test is the most common NDT method currently used for this purpose. However, estimating compressive strength using general regression models can often yield inaccurate results. The experiment results show that the compressive strength of any concrete can be estimated using one’s own newly created regression model. A traditionally constructed regression model can predict the strength value with 50% reliability, or when two-sided confidence bands are used, with 95% reliability. However, civil engineers usually work with the so-called characteristic value defined as a 5% quantile. Therefore, it appears suitable to adjust conventional methods in order to achieve a regression model with 95% one-sided reliability. This paper describes a simple construction of such a characteristic curve. The results show that the characteristic curve created for the concrete in question could be a useful tool even outside of practical applications.

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Zahoor, Aun, Muhammad Usman Azhar, Saif Ur Rehman, and Farrukh Rahim Shehzad. "A Comparison Between Schmidt Rebound Hammer Test and Point Load Index Test (IS50) for the Effectiveness in Estimating the Unconfined Compressive Strength of Intact Rock- A Case Study with respect to Limestone of Early Eocene Nammal Formation, Central Salt." International Journal of Economic and Environmental Geology 10, no. 2 (September 19, 2019): 139–44. http://dx.doi.org/10.46660/ijeeg.vol10.iss2.2019.283.

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In a bid to find some possible relation of Unconfined Compressive Strength (UCS) with relatively simplelaboratory tests like Point Load Test (PLT) and Schmidt Rebound Hammer Test (SRHT), some 50 core samples ofMiddle Eocene Nammal formation from Central Salt Range in Pakistan were collected and subjected to these testmethods as per respective test standards of International Society of Rock Mechanics (ISRM). The values of SRHT andPLT were separately compared to the respective values of UCS so as to find the linear relations. On the basis of the R2value of Regression Analysis, it has been found that a strong correlation with a high degree of accuracy exists betweenPLT and UCS while the degree of accuracy between SRHT and UCS was found to be low.

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36

Zahoor, Aun, Muhammad Usman Azhar, Saif Ur Rehman, and Farrukh Rahim Shehzad. "A Comparison Between Schmidt Rebound Hammer Test and Point Load Index Test (IS50) for the Effectiveness in Estimating the Unconfined Compressive Strength of Intact Rock- A Case Study with respect to Limestone of Early Eocene Nammal Formation, Central Salt." International Journal of Economic and Environmental Geology 10, no. 2 (September 19, 2019): 139–44. http://dx.doi.org/10.46660/ojs.v10i2.283.

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In a bid to find some possible relation of Unconfined Compressive Strength (UCS) with relatively simplelaboratory tests like Point Load Test (PLT) and Schmidt Rebound Hammer Test (SRHT), some 50 core samples ofMiddle Eocene Nammal formation from Central Salt Range in Pakistan were collected and subjected to these testmethods as per respective test standards of International Society of Rock Mechanics (ISRM). The values of SRHT andPLT were separately compared to the respective values of UCS so as to find the linear relations. On the basis of the R2value of Regression Analysis, it has been found that a strong correlation with a high degree of accuracy exists betweenPLT and UCS while the degree of accuracy between SRHT and UCS was found to be low.

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Hing Kwong, Tang, Rudy Tawie, and Siti Rozana Romali. "Forensic to the Reinforced Concrete (RC) Structures at Library." Journal of Advanced Research in Applied Sciences and Engineering Technology 19, no. 1 (June 30, 2020): 6–14. http://dx.doi.org/10.37934/araset.19.1.614.

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This Forensic project has been proposed to investigate the reinforced concrete structure defect at library. There were found 65 points cracks and 20 points spalling in library such as only at reinforced concrete beam and slab part in first floor. The total of cracks which crack width less than 0.25 mm is 63 points and the crack width between 0.25 mm to 5.00 mm is 2 points only. These cracks had categorized as fine cracks because the crack width not more than 5 mm. There was 21 samples Rebound Hammer test was random measured the existing concrete compressive strength of critical structures which six samples at beams, six samples at slabs, six samples at columns and three samples at staircase in library. The Rebound Hammer test shown that average mid-point strength at beam is 33 N/mm2, slab is 25 N/mm², column is 38 N/mm2 and staircase is 37 N/mm2 . Based on the Eurocode 2, the minimum grade concrete required is 25N/mm2 to do the design for reinforced concrete structures, which all the existing concrete strength were achieved the minimum concrete strength. Finally, the Orion software are used to analysis and determine the size of steel reinforcement, the design found the required bar size of steel reinforcement at the middle span or continuous support is 2T16 & 2T25 or 2T20 & 2T25 but the existing steel reinforcement is 2T12 and 2T20 which the existing steel reinforcement could not be sustained the big loading that applied on the library.

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Concu, Giovanna, Barbara de Nicolo, Luisa Pani, Nicoletta Trulli, and Monica Valdés. "Prediction of Concrete Compressive Strength by Means of Combined Non-Destructive Testing." Advanced Materials Research 894 (February 2014): 77–81. http://dx.doi.org/10.4028/www.scientific.net/amr.894.77.

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The problem of estimating mechanical properties of buildings materials is a major issue in civil engineering, especially when dealing with existing structures. In such occasion a valuable help is given by Non Destructive Testings, which allow materials characteristics to be evaluated in a non-invasive way. This paper analyses the efficacy of the SonReb method - a non destructive technique which statistically combines the results of Ultrasonic and Rebound Hammer Testing in predicting concrete compressive strength. The SonReb method has been applied on concrete specimens later on exposed to compressive strength test. The effectiveness of several empirical formulas expressing SonReb results is illustrated and discussed.

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Atoyebi, O. D., O. P. Ayanrinde, and J. Oluwafemi. "Reliability Comparison of Schmidt Rebound Hammer as a Non-Destructive Test with Compressive Strength Tests for different Concrete Mix." Journal of Physics: Conference Series 1378 (December 2019): 032096. http://dx.doi.org/10.1088/1742-6596/1378/3/032096.

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Kazemi, Mostafa, Mohammad Hajforoush, Pouyan Khakpour Talebi, Mohammad Daneshfar, Ali Shokrgozar, Soheil Jahandari, Mohammad Saberian, and Jie Li. "In-situ strength estimation of polypropylene fibre reinforced recycled aggregate concrete using Schmidt rebound hammer and point load test." Journal of Sustainable Cement-Based Materials 9, no. 5 (March 10, 2020): 289–306. http://dx.doi.org/10.1080/21650373.2020.1734983.

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Saha, Anindya Samya, and Khan Mahmud Amanat. "Rebound hammer test to predict in-situ strength of concrete using recycled concrete aggregates, brick chips and stone chips." Construction and Building Materials 268 (January 2021): 121088. http://dx.doi.org/10.1016/j.conbuildmat.2020.121088.

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Snezhkov, D. "On the calibration dependencies designing for concrete strength testing by sclerometric nondestructive metods." Ways to Improve Construction Efficiency, no. 45 (October 16, 2020): 16–25. http://dx.doi.org/10.32347/2707-501x.2020.45.16-25.

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Sclerometric methods of testing concrete, in particular, the rebound hammer testing, retain their positions as the most common indirect methods for concrete strength determining in situ. They are used as a means for technological testing during the buildings construction, as well as during their inspection during maintenance. Indirect parameters of current sclerometric devices are usually point-values: the rebound index, the diameter and depth of the print, the duration of the indenter insertion process, and the maximum interaction force. However, the lack of an unambiguous relationship between these parameters and the strength of concrete leads to additional uncertainty of the test result, which is one of the problems of sclerometric methods of concrete control. The instability of the calibration dependencies of the method is also observed. Even strict compliance with the requirements of the procedure does not guarantee the repeatability of the obtained dependencies.The article considers the possibility of improving metrological indicators of calibration dependencies of sclerometric methods by introducing an additional parameter-concrete humidity. The possibility of combining two sclerometric methods – the elastic rebound method and the shock pulse method is also considered. Data were obtained on concrete samples with a curing time of 25..60 days. Two-parameter calibration dependencies, including concrete humidity as an additional parameter, allowed for all experimental series of samples to reduce the residual mean square deviation of the calibration dependence of elastic rebound and shock pulse methods by 10%..16%, and to consistently provide the minimum acceptable value of the correlation coefficient r = 0.7 for the studied concrete compositions. The influence of concrete heterogeneity on the readings of sclerometric test methods is considered.The developed method of constructing two-parameter calibration dependencies can be recommended for inclusion in the current standards governing the determination of the strength of concrete structures under construction.

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Johari, Izwan B., Md Azlin Md Said, Mohd Amirul B. Mohd Snin, Nur Farah Aqilah Bt Ayob, Nur Syafiqah Bt Jamaluddin, and Mohamad Rohaidzat Bin Mohamed Rashid. "Effect of Treated Sago Pith Waste Ash and Silica Fume to the Mechanical Properties of Fly Ash-Based Geopolymer Brick." Key Engineering Materials 879 (March 2021): 100–114. http://dx.doi.org/10.4028/www.scientific.net/kem.879.100.

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This paper investigates the effect of partial replacement of fly ash with sago pith waste ash and silica fume in fabricating the geopolymer mortar concrete. The mixtures of geopolymer mortar concrete were prepared by replacing sago pith waste ash and silica fume at 5% of total weight of fly ash. There were six specimens of geopolymer mortar cubes and bricks fabricated in this study. The specimens are tested with compressive strength test, rebound hammer test and ultrasonic pulse velocity test. The results from the tests are compared with some existing published works as to clarify the effect of replacing the fly ash with sago waste and silica fume on the strength of concrete. Comparisons had been made and concluded that the molarity of alkaline solution, Al3O2 and CaO influenced the development of compressive strength along the curing time of fly ash based geopolymer concrete.

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Abdel Rahim, Khalid Abdel Naser. "Evaluating Concrete Quality using Nondestructive In-situ Testing Methods." Revista Tecnología y Ciencia, no. 36 (October 10, 2019): 22–40. http://dx.doi.org/10.33414/rtyc.36.22-40.2019.

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This manuscript investigate the quality of concrete using non-destructive in-situ testing.The in-situ testing is a process by which different test are carried out such as rebound hammer, ultrasonic pulse veloc-ity, initial surface absorption test and fig air, to determine thein-situ strength, durability and deterioration, air permeability, concrete quality control andperformance. Additionally, the quality of concrete was researched using test methods with experimental results. Moreover, this research has found that (1) the increase in w/c ra-tioleads to a decrease in compressive strength and ultrasonic pulse velocity. Thus, lower w/cratio gives a bet-ter concrete strength in terms of quality, (2) the quicker the ultrasonic pulse travels through concrete indicates that the concrete is denser, therefore, better quality, (3) the lower initial surface absorption value indicates a better concrete with respect to porosity and (4) the w/c ratio plays an important role in the strength and per-meability of concrete.

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Mang, Wong Jia, Abdul Ghani Md Rafek, and Goh Thian Lai. "Issues in Engineering Geological Classification of Weathered Sedimentary Rocks: Case Study of Kati Formation, Parit, Perak." International Journal of Engineering & Technology 7, no. 4.35 (November 30, 2018): 131. http://dx.doi.org/10.14419/ijet.v7i4.35.22341.

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Kati Formation consists of alternating layers of sandstone, siltstone and mudstone that results in non-uniform weathering. The presence of surficial features due to weathering such as iron bands, iron recementation, iron staining and lithobionts coating in an uneven distribution on the outcrop causing more complexity to the heterogeneous sedimentary rocks which are also tectonically deformed. The presence of iron recementation in highly weathered rocks causing the rock strength to be higher than the moderately weathered rocks. Thus, several laboratory tests are conducted in this study to characterise the weathered rocks which are uniaxial compressive strength (UCS), point load strength index, slake durability test, jar slake test and Schmidt hammer rebound test. Among the laboratory tests conducted in this study, slake durability index test, Id2 is the ideal test to characterise the rock samples of different weathering grades as it gives a large range of laboratory test results which is 0.3 % to 15.0 % for completely weathered, 22.0 % to 67.0 % for highly weathered, 68.0 % to 83.0 % for moderately weathered and 87.0 to 98.0 % for slightly weathered to fresh rocks. The values obtained are not affected by the uneven distribution of iron oxide present in the rock samples.

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Shogaki, T., and Y. Inaba. "Characteristics of multi strike surface strength of stones, concrete and bricks used for historical structures since Meiji era in Japan." BULLETIN of L.N. Gumilyov Eurasian National University. Technical Science and Technology Series 134, no. 1 (2021): 58–67. http://dx.doi.org/10.32523/2616-7263-2021-134-1-58-67.

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Historical structures are part of the heritage humankind hands down to posterity. As records, they not only describe past construction technologies, but they also carry information about the social system and culture of their time. Many historical civil engineering structures constructed during and after the Edo era still remain in Japan. Some of these structures, such as the Yokosuka dry docks, played an important role in the fate of the nation (Shogaki, 2014). However, such sites have not been the subject of systematic geotechnical research or publicity. The strength of construction materials at historical sites built since the Meiji era was investigated using the rebound hammer test (JGS 2013) and evaluated with regard to construction age, facility use, and material. The tested materials were rocks (andesite, granite, and sandstone) at 10 sites, concrete at 6, and brick at 3.

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Du, Guoqiang, Liangtao Bu, Qi Hou, Jing Zhou, and Beixin Lu. "Prediction of the compressive strength of high-performance self-compacting concrete by an ultrasonic-rebound method based on a GA-BP neural network." PLOS ONE 16, no. 5 (May 3, 2021): e0250795. http://dx.doi.org/10.1371/journal.pone.0250795.

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To address the problem of low accuracy and poor robustness of in situ testing of the compressive strength of high-performance self-compacting concrete (SCC), a genetic algorithm (GA)-optimized backpropagation neural network (BPNN) model was established to predict the compressive strength of SCC. Experiments based on two concrete nondestructive testing methods, i.e., ultrasonic pulse velocity and Schmidt rebound hammer, were designed and test sample data were obtained. A neural network topology with two input nodes, 19 hidden nodes, and one output node was constructed, and the initial weights and thresholds of the resulting traditional BPNN model were optimized using GA. The results showed a correlation coefficient of 0.967 between the values predicted by the established BPNN model and the test values, with an RMSE of 3.703, compared to a correlation coefficient of 0.979 between the values predicted by the GA-optimized BPNN model and the test values, with an RMSE of 2.972. The excellent agreement between the predicted and test values demonstrates the model can accurately predict the compressive strength of SCC and hence reduce the cost and time for SCC compressive strength testing.

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Martínez-Molina, Wilfrido, Andrés Antonio Torres-Acosta, Juan Carlos Jáuregui, Hugo Luis Chávez-García, Elia Mercedes Alonso-Guzmán, Mario Graff, and Juan Carlos Arteaga-Arcos. "Predicting Concrete Compressive Strength and Modulus of Rupture Using Different NDT Techniques." Advances in Materials Science and Engineering 2014 (2014): 1–15. http://dx.doi.org/10.1155/2014/742129.

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Quality tests applied to hydraulic concrete such as compressive, tension, and bending strength are used to guarantee proper characteristics of materials. All these assessments are performed by destructive tests (DTs). The trend is to carry out quality analysis using nondestructive tests (NDTs) as has been widely used for decades. This paper proposes a framework for predicting concrete compressive strength and modulus of rupture by combining data from four NDTs: electrical resistivity, ultrasonic pulse velocity, resonant frequency, and hammer test rebound with DTs data. The model, determined from the multiple linear regression technique, produces accurate indicators predictions and categorizes the importance of each NDT estimate. However, the model is identified from all the possible linear combinations of the available NDT, and it was selected using a cross-validation technique. Furthermore, the generality of the model was assessed by comparing results from additional specimens fabricated afterwards.

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Mohammed, Diyari A., and Younis M. Alshkane. "Tensile Strength Modeling of Limestone Rocks in Sulaymaniyah City, Iraq Using Simple Tests." Polytechnic Journal 9, no. 2 (December 1, 2019): 149–55. http://dx.doi.org/10.25156/ptj.v9n2y2019.pp149-155.

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Tensile strength of rocks is one of the mechanical properties of intact rock that is a significant parameter for designing geotechnical structures includes dam foundations and tunnels. The tensile strength can be determined indirectly using Brazilian indirect test procedure that is mentioned in the International Society for Rock Mechanics suggested methods. The availability of rock samples is needed to perform the Brazilian indirect test so as to determine their tensile strength which is expensive, time-consuming, and cost-effective especially for weak quality rock formations. Therefore, non-destructive methods for predicting the tensile strength of the rock are crucially needed during the poor quality of rock samples. Non-destructive tests can be correlated with indirect tests to predict Brazilian tensile strength (BTS) of rocks such as ultrasonic pulse velocity and Schmidt hammer. These methods are simple and can be easily conducted in the field. This study is focused on the tensile strength of limestone rocks for three main formations of Sulaymaniyah city. The samples were obtained using a standard core barrel. Statistical analysis including minimum, maximum, mean, standard deviation, variance, and coefficient of variance for the results was conducted. Single and multiple correlations between BTS and each of ultrasonic pulse velocity and Schmidt hammer rebound number of limestone rocks were created. Reasonable empirical equations were developed to predict the tensile strength of limestone rocks. In addition, the point load strength index was correlated with BTS. The comparison between proposed equations from this study and equation from the literature was also investigated.

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Tsai, Meng Ting, Chung Hsien Shih, Yu Chun Lin, and Chia Chi Cheng. "Inspection of Hyperbolic Reinforced Concrete Shells-Luce Memorial Chapel-Based on Nondestructive Testing Method." Key Engineering Materials 735 (May 2017): 113–18. http://dx.doi.org/10.4028/www.scientific.net/kem.735.113.

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This paper is aimed to inspect the chapel’s overall structural system based on nondestructive testing (NDT), and a rebound hammer test and a ground-penetrating radar (GPR) system are employed to conduct a nondestructive testing. It is important before the chapel’s structural performance was assessed, the structure was inspected to investigate the current state and was constructed according to its original structural designs. According to the inspection, it is found the concrete compressive strength of all the components is larger than the original design strength. Moreover, the total numbers of the reinforcing bars of Slabs S1 and N1 are consistent with the number in the original design (246). However, the total numbers of the reinforcing bars of Slabs S2 and N2 are 167 and 174, respectively, whereas those of the original design were 150, indicating additional vertical reinforcing bars were applied in the chapel’s construction. Based on the results of inspection, the future structural performance assessment and retrofitting are expected to be set-up properly.

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Journal articles on the topic 'Rebound hammer test'

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