Fig. 16. Variarion of concrete compressive strength vs. UPV for different fine/coarse (F/C) aggregate ratios. Samples with w/c = 0.4 (Madandoust, 2010)
4. Special applications of UPV in cementitious composites
The objective of this section is to show a few practical examples of the utilization of ultrasonicpulsevelocity as a non-destructive characterization technique for cementitious composites. It obviously does not cover all applications, but rather gives an overview of special or novel systems to where UPV can be employed. UPV has been largely used on the assessment of the uniformity of concrete, as well the detection of defects in concrete structures. The non-uniformity is indicated by the variation of the pulse velocities obtained from different points (Komlos et al., 1996). However, other examples below show that the application of this non-destructive technique goes beyond the original idea of detection of large voids or cavities in structural concrete.
Black cotton soil which is one of the major soil deposits which accounts for more than 50% of soil in India and is highly problematic because of its property of higher degree of swelling and shrinkage. These soils are used in sub grade of pavement and also in construction of structures. Hence in order to improve the properties of such soils many methods are available like soil stabilization, soil replacement, moisture control etc. In recent years, soil stabilization by using various minerals like quarry dust, saw dust, copper dust, cement and fly ash were most commonly used. In the present study cement is used as admixture and NDT was performed on clayey soil compacted by rolling compactor cum rut analyzer. The experiment was conducted with varying proportions of cement and the relation between maximum dry density, moisture content, pulsevelocity etc were determined. lab test specimens were prepared and wave velocity was measured for each of the compacted stabilized specimen. in this paper the Maximum dry density of the soil is related with the obtained velocity and thus real time density is obtained in field by simple ultrasonicpulsevelocity test.
The ultrasonicpulsevelocity method has been used successfully to evaluate the quality of concrete for more than 75 years. This method can be used for detecting internal cracking and other defects as well as changes in concrete such as deterioration due to aggressive chemical environment and freezing and thawing. The pulsevelocity method is a truly non-destructive method, as the technique uses mechanical waves resulting in no damage to the concrete element being tested. A test specimen can be tested again and again at the same location, which is useful for monitoring concrete undergoing internal structural changes over a long period of time.
2 Fast Reactor Fuel Cycle Facility, Indira Gandhi Centre for Atomic Research, Kalpakkam, India
Received: 28/032/2016 – Revised: 28/04/2016 – Accepted: 25 /05/2016
Objective of this study is to evaluate the effect of compressive stress over non-destructive assessment of field concrete using ultrasonicpulsevelocity (UPV). Influence of compressive stress on UPV for different concrete grades (M25, M30 & M40) tested at laboratory and at field on M40 reinforced concrete (RC) columns of 42 m height of a high bay building is discussed. It is found that there is an increase in pulsevelocity for concretes stressed around 5 MPa in addition to the growth in velocity due to water to cement ratio and curing period for cubes tested after 7, 14, and 28 days water curing. In the field study, pulsevelocity versus computed stress due to construction loads transmitted at various stages of the RC columns prove that grow in velocity is significant with respect to acting stress and curing age. The results obtained from the study can be used as a reference for concrete ageing programs wherein pulsevelocity based assessment is an important tool.
Abstract — This paper investigates the relationship between the ultrasonicpulsevelocity (UPV) and the compressive strength of concrete. The specimens used in the study were made of concrete with a varied cube compressive strength from 18 to 55MPa. Number of specimens was over 800 received from various construction projects of controlled concrete quality and tested by the Hawler Construction Laboratories (HCLabs) in Erbil, Kurdistan Region of Iraq, during the last half of 2014.
This paper investigates the efficiency of UltrasonicPulseVelocity (UPV) method in detecting cracks and flaws inside the concrete. A series of concrete beams and slab specimens were cast and damaged to simulate the different mechanisms possible in a reinforced concrete deck due to mechanical loading. Two types of simulated cracks, namely, cracks perpendicular and cracks parallel to axis of beam were induced without actually breaking the beam. An ideal vertical crack was simulated by introducing a cut perpendicular to the axis of the beam using a diamond tipped concrete cutter and a real crack was simulated by inserting a thin sheet of plastic while casting the beam. Horizontal cracks were simulated using lower acoustic impedance materials like thermocole and polyvinyl chloride inserted at a known distance while casting the specimen. Materials with less acoustic impedance as compared to that of concrete have good reflectivity and hence would simulate the damage accurately. The results indicate that the pulsevelocity method can be used effectively to measure the crack depth of vertical cracks. The depths can be measured with high degree of accuracy, if the distance between the transducers is maintained between 100 - 200 mm. However, for horizontal cracks, this method does not prove to be accurate and effective in measuring the location of cracks. But within a distance of 100-200 mm between the transducers, the depth of the horizontal cracks can be estimated to a reasonable degree of accuracy. Hence, the distance between the transducers plays a vital role in the accuracy of depth measurement. This is because, if the distance between the transducers is less than 100 mm, then the surface wave reaches the receiver before the reflected compression waves and leads to lower values of depth. Also, if the depth is more than 200 mm, there are possibilities of multiple reflections and hence there is an error in measurement.
It has been investigated the ultrasonicpulsevelocity as it is described in ASTM C597-09 and compressive strength as it is described in ASTM C 39 M.
Prismatic sample have been prepared by dimension 16x16x40 mm to measure ultrasonicpulsevelocity. On the other hand cubic specimens have been prepared by dimension 150mmx150 mm to measure compressive strength. Tables 4,5,6,7,8,9 show the results obtained for compressive strength and ultrasonicpulsevelocity at room temperature, 200 0 C, 600 0 C.
--------------------------------------------------------------------***----------------------------------------------------------------------- Abstract: There are many test methods to assess the strength of in situ concrete, such us non-destructive test method namely one such technique was Ultrasonicpulsevelocity (UPV). These methods are considered indirect and predicted tests to determine concrete strength at the site. These tests are affected by many parameters that depends on the nature of materials used in concrete production. So, there is a difficulty to determine the strength of hardened in situ concrete precisely by these methods. In this research, the UPV test is used to assess the concrete compressive strength. From the results of this research it is intended to obtain a statistical relationship between the Concrete compressive strength and Ultrasonicpulsevelocity. In this research work, UPV test was carried out by considering direct transmission (on opposite faces) method. It’s possible to interpret an acceptable equation that can be used to measure the compressive strength from the (UPV) value. This arrangement is the most preferred arrangement in which transducers are kept directly opposite to each other on opposite faces of the concrete. The transfer of energy between transducers is maximum in this arrangement. The accuracy of velocity determination is governed by the accuracy of the path length measurement. Thus the objectives of this present research are threefold. First, this research will examine the influence of conditioning such as drying condition on the results of UPV test performed on concrete cubes with different mixtures proportion. In which Slump, and w/c ratio value was varied with constant compressive strength as in the First case and compressive strength, and w/c ratio value varied with constant slump as in the Second case. Seventy-two concrete cubes (100 mm 3 ) with grades of concrete ranges from 25 to 40 N/mm 2 were prepared and tested using UPV test. The non-destructive test parameters were related to different mixtures proportion in ordered to characterize mix designs. Second, this research will examine the influence of the UPV value on compressive strength. Third, this research will also aims to develop non-destructive charts for different concrete mixtures proportion. This implied that the developed chart was more suitable for normal strength concrete. As well as can be utilised in minimising inaccuracy in non-destructive tests.
b IGMAT d.d., Building Materials Institute, Polje 351c, Ljubljana, Slovenia
Ultrasonicpulsevelocity technique is one of the most popular non-destructive techniques used in the assessment of concrete properties. However, it is very difficult to accurately evaluate the concrete compressive strength with this method since the ultrasonicpulsevelocity values are affected by a number of factors, which do not necessarily influence the concrete compressive strength in the same way or to the same extent. This paper deals with the analysis of such factors on the velocity-strength relationship. The relationship between ultrasonicpulsevelocity, static and dynamic Young's modulus and shear modulus was also analyzed. The influence of aggregate, initial concrete temperature, type of cement, environmental temperature, and w/c ratio was determined by our own experiments. Based on the experimental results, a numerical model was established within the Matlab programming environment. The multi-layer feed-forward neural network was used for this purpose. The paper demonstrates that artificial neural networks can be successfully used in modelling the velocity-strength relationship. This model enables us to easily and reliably estimate the compressive strength of concrete by using only the ultrasonicpulsevelocity value and some mix parameters of concrete.
Non-destructive testing by using ultrasonicpulsevelocity method was performed on compacted clayey soil. The various physical properties of the soil were determined. Further laboratory specimens were prepared for varying percentages of GGBS and moisture contents by Standard Proctor method. Wave velocity by direct transmission was determined for all the specimens and optimum moisture contents for each of the percentages of GGBS was determined. Slabs were cast for soils with varying percentages of GGBS and their corresponding optimum moisture contents. Wave velocities were determined for both direct and indirect transmission. Cores were made and respective densities were determined. All the specimens tested exhibited an increase in pulsevelocity with increase in dry density until optimum moisture content was obtained and a rapid decrease in velocity with further increase in water content. The observations made were in conformity to the research made earlier. The parameters investigated include water content, dry density, soil characteristics and the relationship between velocity and density.
National Geophysical Research Institute, Hyderabad-500 007
A strong laboratory database of mechanical and engineering properties of rocks is very useful for site characterization and mining engineering applications. Owing to the discontinuous and variable nature of rock masses, it is difficult for rock engineers to directly obtain the specific design parameters of interest. As an alternative, they use empirical or analytical relationships among various physical and mechanical strength properties of materials to estimate the required engineering properties of rocks and other brittle materials of interest. We have found recently that the UltrasonicPulseVelocity (UPV) can also be used to estimate the engineering properties of rocks. We have carried out UltrasonicPulseVelocity (UPV) measurements and Uniaxial Compressive Strength (UCS) tests on a large number of sandstone samples of coal mining industry in our laboratory. The engineering properties such as brittleness, hardness, fracture toughness and drillability index of rocks have been obtained. It is found that there is a fairly good correlation between UPV & UCS and UPV & the above mentioned engineering properties of sandstones.
2. College of Engineering, Al Imam Mohammad Ibn Saud Islamic University, Riyadh, KSA
* Corresponding Author: E-mail: firstname.lastname@example.org
Nondestructive evaluation of existing structures is a vital part and an active area of research in civil engineering industry. Whenever modifications in a structure or its use are proposed the process begins with the evaluation of existing condition. Rebound hammer (RH) and ultrasonicpulsevelocity (UPV) tests are the two readily available and easy-to-perform methods that are widely used in the industry. Current research work is focused on evaluation of an eight years old, half-built reinforced concrete building. The objective was to gather information to decide about the future construction and use. The study concludes that concrete is of reasonable quality and building is appropriate for future construction and use. However, one column in the basement has very poor quality concrete and needs strengthening. Paper also provides a comparison of existing regression models for the prediction of concrete strength based on RH and UPV test data.
Keywords: -Compressive Strength, Estimation, Structural Timber, UltrasonicPulseVelocity Method
Diagnosis is essential to figure out defect construction and condition of structure. There are various diagnostic methods among which nondestructive test method is the most convenient method. With the nondestructive test method, while diverse studies have been actively progressed by concrete and steel structure assessment standard and regulation, it is hard to make accurate diagnosis on wood structure as tissues are different and uneven by types of timber. As such safe use of wood structure is necessary by means of maintenance and diagnosis in line with enhanced interest in safety. This study aims to analyze correlation of compressive strength by ultrasonicpulsevelocity, a kind of nondestructive test method and also to propose reliable compressive strength estimation of structural timber. Based on these data, this study is expected to be used as reliable maintenance and diagnosis index of wood structure for field application despite insufficient regulation.
2-6-Testing of Hardened Concrete 2-6-1-Ultrasoic PulseVelocity Test:
The principle of ultrasonicpulsevelocity measurement involves sending a wave pulse into concrete and measuring the travel time for the pulse to transmit through the concrete. In this method an ultra-sonic pulse is generated by a pulse generator and transmitted to the surface of concrete through the transmitter transducer. The time traveled by the pulse through the concrete is measured by the receiver transducer on the opposite side.In order to ensure effective transfer of the wave between concrete and transducer, a thin grease layer is applied to the surface of transducer.
Cengiz KURTULUS, Fadime SERTÇELIK, Ibrahim SERTÇELIK
Abstract: Unconfined Compressive Strength (UCS) of the rocks plays a significant role in geotechnical and rock engineering projects. Due to difficulties UCS estimation is done using indirect methods such as Schmidt Rebound Hammer (RN) and UltrasonicPulseVelocity (UPV) tests that are quick and inexpensive tests. This study was performed to provide data consisting of correlations between RN versus UPV and UCS for rock materials. RN and UCS and UPV tests were carried out on 66 rock specimens from 6 different rock samples in the laboratory. Linear models were used for the relations between RN and UCS and UPV because R 2 values of linear model is more suitable than non-linear models. The equations proposed in this study can be used easily for the areas formed of sandstone, limestone, arkoses, and granite to pre-estimate the UCS values of the rocks.
In this study, engineering properties of composites containing polyurethane, wheat stalk and corn stalk ash, peanut shell ash, fly ash, sawdust, perlite, barite and gypsum are investigated.
Radiation absorption, unit weights, ultrasonicpulse velocities, thermal insulation coefficients of the specimens produced in standard 16x16x4 cm molds were found. All tests were found to be in accordance with standards. Also, it was found out that specimen no. 3 has the lowest thermal insulation coefficient. It was found out that specimens containing more sawdust have higher unit weight. Specimens with high thermal insulation coefficient and unit weight were found to have low capacity of ultrasonic sound absorption. This case was explained with spaceless structure of materials. It was found that specimen no.3 with the lowest ultrasonicpulsevelocity has the lowest thermal insulation coefficient. Unit weight for the same specimen was found to be under average. It was found that specimens containing peanut shell ash have higher radiation absorption rates. This study showed that wheat stalks, corn stalks and peanut shells can be recycled for economy by burning process in appropriate environment. Also, this composite can protect people from negative effects of radiation when used in medical buildings and X-ray rooms.
The article examines the residual compressive strength and ultrasonicpulsevelocity of concrete that has been cured with water after exposure to elevated temperatures.
The relationship between the residual strength ratio and the residual UPV ratio was developed. Cubic specimens were made of concrete with water-cement ratios of 0.35 after 56 days, the samples were heated in an electric furnace at temperatures ranging from 400 to 600 ° C. The speed of the ultrasonicpulse and the compressive strength of each test piece after curing of fire are measured immediately after 24 hours of cooling. The results obtained indicate that the application of UPV has demonstrated to be a trustworthy analysis, being able to prove the effectiveness of its use on fire-damaged concrete structures.
This paper presents the experimental investigation results of UltrasonicPulseVelocity (UPV) testing conducted on Roller Compacted Concrete (RCC) containing Ground Granulated Blast furnace Slag (GGBS) as mineral admixture and manufactured sand (M-sand) as partial replacement of fine aggregate (50%). The UPV was determined at the age of 24 hours, 3 days, 7 days, 14 days, 28 days and 90 days for seven RCC mixtures using cube specimens of plain and GGBS Roller Compacted Concrete (GRCC). The amount of OPC replaced by GGBS was varying from 0% to 60%. The UPV of GRCC was found to be lower for all mixtures at 24 hours in comparison with control mix concrete. But at 3, 7,28and 90 days the Ultrasonicpulse velocities were significantly improved for all the mixes. Relationships between compressive strength of GRCC and UPV and Dynamic Elastic Modulus were proposed. A new model is proposed to determine the Dynamic Elastic Modulus of GRCC as a function of age of concrete and percent replacement of GGBS by Ultrasonic Method.
using the UPV test, which have resulted in positive findings [22–27]. Entrapped air bubbles and the porosity inside a solid object affect the way by which ultrasonic pulses travel through it. Multiple different factors including the cement type, water- cement ratio, concrete age, aggregate type, curing method, measuring distance, and the measuring region’s temperature affect the ultrasonicpulsevelocity [17–20]. Extenside research has addressed the effect of different parameters on the UPV [28– 32]. In their work, Rommel and Malhotra reported on the UPV in concrete specimens having different water-to-cement ratios and gravel volumes. In terms of different variables in the concrete specimens, they reached different UPVs, and subsequently proposed a pattern for evaluatiing concrete quality [28,29]. Given smaller number of air bubbles present in self-compacting concrete relative to conventional concrete because of its specific properties as well as the powder ingredient, this study attempted to evaluate the efficiency of the nondestructive technique in self- compacting concrete containing fibers. The aim was to develop a relationship between compressive strength and the UPV in this concrete. Here, 11 mix designs including different percentages of steel, Poly- phenylene Sulfide (PPS) and poly- propylene (PP) fibers were used to prepare the concrete specimens.
1 University of Delaware; email@example.com
2 University of Lagos; firstname.lastname@example.org
* Correspondence: email@example.com
Abstract: This work investigates the use of Non-destructive tests as a tool for monitoring the structural performance of concrete structures. The investigation encompassed four phases; the first of which involved the use of destructive and non-destructive mechanisms to assess concrete strength on cube specimens. The second phase research focused on site assessment for a twin engineering theatre located at the Faculty of Engineering, University of Lagos using rebound hammer and ultrasonicpulsevelocity tester. The third phase was the use of linear regression analysis model with MATLAB to establish a relationship between calibrated strength as well as ultrasonicpulse velocities with their corresponding compressive strength values on cubes and values obtained from existing structures. Results show that the root-mean squared-R 2 values for rebound hammer ranged between 0.275 and 0.742 while ultrasonicpulsevelocity R 2 values were in the range of 0.649 and 0.952 for air curing and water curing systems respectively. It initially appeared that the Ultrasonicpulsevelocity was more suitable for predicting concrete strength than rebound hammer but further investigations showed that the latter was adequate for early age concrete while the former was more suited for aging concrete. Hence, a combined use is recommended in this work.