scholarly journals Evaluation of Concrete Quality for Reinforced Concrete Frame Members Exposed to Natural Fires at Early Ages Using in situ Test Methods

2019 ◽  
Vol 13 (1) ◽  
pp. 201-209
Author(s):  
Muhammad I. Omer ◽  
Dilshad K. Jaf
Keyword(s):  
Reinforced Concrete ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Early Age ◽  
Concrete Frames ◽  
Natural Fire ◽  
Concrete Quality ◽  
Fire Accidents

Background: In recent years, numerous reinforced concrete buildings have been constructed in Iraq and some developing countries. Fire accidents occur in wooden formwork especially during the summer season due to problems associated with the construction procedure and on-site management. And fires can erupt during the construction stage of buildings. Introduction: Generally, if fire accidents occur in a wooden formwork, in these situations the concrete in the field is at an early age (i.e., “young”). The internal structure and chemical composition of early-age concrete are different from that of the carrier due to incomplete hydration at an early age. This study aimed to evaluate the strength of reinforced concrete frames at early ages when exposed to natural fire. The evaluation of existing buildings is an important issue that involves researchers and engineers in many countries. Methods: The experimental program consisted of constructing three full-scale reinforced concrete frames that are then exposed to natural fire. When the concrete age reaches three and five days by firing its formwork, the concrete quality of the structure was evaluated via ultrasonic pulse velocity as a nondestructive measurement. Core test was used as a destructive technique to implement a relationship between compressive strength and nondestructive measurements Results: The results showed that the frame exposed to natural fire early was generally more affected than the other frame, and its compressive strength was reduced close to 33%. The results also showed that the ultrasonic pulse velocity test for the structural elements was smaller than those of the core test Conclusion: It can be concluded that the current assessment methodology must be evaluated to provide practical suggestions that can enhance the reliability of assessing the in situ strength of existing concrete structures by nondestructive tests and cores.

scholarly journals Evaluating Concrete Quality using Nondestructive In-situ Testing Methods

2019 ◽  
pp. 22-40
Author(s):  
Khalid Abdel Naser Abdel Rahim
Keyword(s):  
Concrete Strength ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Initial Surface ◽  
In Situ Testing ◽  
Surface Absorption ◽  
Concrete Quality

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.

scholarly journals The assessment of concrete quality by ultrasonic pulse velocity

2018 ◽  
Vol 12 (5) ◽  
pp. 20-27
Author(s):  
Van Viet Thien An
Keyword(s):  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Internal Defect ◽  
Internal Defects ◽  
Testing Method ◽  
Concrete Quality ◽  
Concrete Elements

In the present study, the uniformity and potential internal defects of concrete elements in situ were assessed by using Ultrasonic Pulse Velocity (UPV) testing method according to TCVN 9357:2012. Thirteen cross beams with dimension of 4.8 x 1.5 x 1.5 m3 were selected to measure the pulse velocity. Three cross beams were used to check potential internal defects in concrete and 10 cross beams were used to assess the uniformity of concrete in the elements. The results showed that there is no potential internal defect with size over 100 mm in three tested beams and concrete quality of all tested beams is good with the coefficient of variation (CV) of ultrasonic pulse velocity results of all tested points is lower than 2%. Keywords: concrete; homogeneity; internal defects; ultrasonic pulse velocity.

scholarly journals In-situ examination of the concrete quality European standard approach

2018 ◽  
Vol 196 ◽  
pp. 02045
Author(s):  
Andrzej Moczko ◽  
Marta Moczko
Keyword(s):  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Velocity Measurements ◽  
European Standard ◽  
Pull Out ◽  
Standard Procedures ◽  
Concrete Quality ◽  
Proper Interpretation

The paper presents overview of European standard procedures related to determining concrete quality basing on the in-situ testing. Among other things following testing methods have been discussed: testing cored specimens, rebound measurements, “pull-out” method, “pull-off” method, ultrasonic pulse velocity measurements. Testing conditions, guidelines for calibration and crucial requirement for proper interpretation of the data obtained by means of rebound and ultrasonic measurements were shown. Independently “pull-out” and “pull-off” NDT methods have been introduced. Finally, the European procedures of assessment of in-situ concrete compressive strength in structures have been also presented.

Ultrasonic Pulse Velocity for In Situ Measurement of Compressive Strength of Concrete

2007 ◽  
Vol 18-19 ◽  
pp. 55-61 ◽  
Author(s):  
C.A. Chidolue ◽  
B.A. Chidolue ◽  
S.N. Umenwaliri
Keyword(s):  
Aggregate Size ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Direct Transmission ◽  
Indirect Transmission ◽  
Mix Proportion ◽  
Compressive Strength Of Concrete ◽  
A Site

In this study, pulse velocities calculated from the time taken by pulses emitted by a transducer to traverse a known thickness of the concrete is utilized in building up a correlation between pulse velocity and strength of concrete cubes and between pulse velocity and age of concrete. Three different arrangements of transmitters and receivers were studied to cover the varieties of problems likely to be encountered on a site. These are direct transmission, semi-direct transmission and indirect transmission. For a particular mix proportion and aggregate size a calibration curve was obtained for in-situ testing of concrete. These curves can be used to determine the relative in-situ strength of similar members or structures.

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