Efficiency of Ultrasonic pulse velocitytest in life of concrete structure

Abstract

Concrete is a basic material used for almost all the engineering projects. Concrete is a composite material, amalgamation of water, cement and aggregates. The concrete comprises of many influential building variables, such as the water/cement ratio, aggregate type and size, humidity and type of cement used in the process. Improper mixing, errors in preparation, excess of admixtures, inadequate workability, honeycombing are some of the major drawbacks of concrete while constructing a concrete structure. All these factors directly affect the quality of concrete and the compressive strength of the concrete. We find it always necessary to detect such trouble causing elements in the structure and to rectify them for long life of concrete structure. UPV test is one of the major tests practiced in order to assess the condition of a structure. This study thoroughly deals with the concept, methodologies, functioning, result of UPV test in understanding the condition of a structure.A random structure is taken and analysed with the Non-destructive testing (UPV), after the repair works carried out as per the analysis of UPV test, the structure is again taken under condition assessment test. The results of both Pre and Post Retrofitting of the RCC structure has been discussed in this paper. NDT is basically an evaluation of condition of concrete in the structure. This has been a vital tool because these methods do not affect the appearance and the performance of the analysed structures. The method allows doing the tests at the same place, making possible a continuous monitoring in the structures and a determination of possible variations during a period of time. Once the structures are monitored, the life-time can be predicted, and consequently, the treatment and the recovery become more easy and economic. The NDT application in India has grown during the last few years. However, the routine procedures are not well known in the civil engineering area. The NDT methods are not reliable to measure the structure strength, but they are useful to analyse the concrete properties and to determine its homogeneity. The correlation between the NDT and the structure strength can be established. The correlations are particular for a certain type of concrete and must be used with caution. Concrete properties can vary considerably depending on the nature and proportions of its materials, the construction methods and the loading and environmental conditions. In order to prevent and control the concrete deterioration, it is interesting to establish continuous monitoring strategies, which might be a powerful tool to increase the service life of concrete. This implies the development of control methods which are able to determine the quality and the condition state of concrete. UPV methods can play an important role in this area, since they allow us to monitor the density and homogeneity of the material, providing information about the strength evolution and about the existence of internal flaws and defects. The UPV methods have been used in inspection operations and monitoring of concrete structures. This test allows to measure and to control a series of basic parameters to determine the concrete quality. However, interpreting the result of this type of test need to be made in a criteriously form and demand a specific knowledge of the influential factors. A series of comparison between pre and post repairing results of UPV test demands some active importance to this test in civil engineering. This study completely indicates the benefits of UPV for condition assessment of concrete structures. II. Ultrasonic Pulse Velocity UPV is a mechanical assembly which is used for over a decade now in India to assess inside condition of a solid material. It is developed over the years and has been in use for several years in civil engineering field for condition assessment of any concrete structure. It is also taken under the Indian Standard for Non-destructive testing method by the civil engineering council and advisory committee of civil engineers in India. (IS- 13311 Part-I).Among the available methods of NDT, the UPV methods can be considered as one of most promising methods for evaluation of the concrete structures, once it makes possible an examination of the material homogeneity. It is possible to obtain a total control of a structure, using the properties variations with the time. The UPV methods make possible the continuous evaluation of concrete conditions during entire service life of structure. The UPV results can be used for diagnosis, prognosis and quality control of concrete structure. The