- January 17, 2018
- Posted by: RSIS
- Categories: Civil Engineering, Concrete Structures, Engineering
International Journal of Research and Scientific Innovation (IJRSI) | Volume V, Issue I, January 2018 | ISSN 2321–2705
Non-Destructive Techniques for Evaluation and Health Monitoring of Concrete Structures- A Review
Chandak N. R.* and Chawla Ashish#
*Professor, Dept. of Civil Engg. NMIMS, MPSTME, Shirpur, M.S, India
#Asst. Professor, Dept. of Civil Engg. NMIMS, MPSTME, Shirpur, M.S, India
Abstract: Authorstried to present the methodologies, merits and demerits besides current work carried in the field of non-destructive techniques (NDT) i.e. ultrasonic pulse velocity (UPV) and rebound hammer (RH). These techniques permits the inspection of larger areas of concrete members at low cost and also provides more information than visual inspection. Influence of w/c ratio, method of casting, direction of casting, dosage of cement on NDT readings has been reported. The intent of this paper is to present the applications of UPV, RH and factors that influence the results. Care that need to take while conducting the NDT tests is also presented.
Keywords- NDT, Rebound hammer, Ultrasonic pulse velocity, Health monitoring of concrete structures
I. INTRODUCTION
As per the latest reports of incident of a five storey building collapsed at JJ junction, Mumbai. Design life of this building were reported 70 years but it collapsed at the age of mere 40 years. Many such other incidents taken place in various corners of India and caused many causalities. It is therefore essential to test concrete structures using NDT before being occupied and at regular interval while in service, to determine whether the structure is suitable for its design use. Non-destructive testing is a method of testing in which the elements or members of structure tested remains totally undamaged. The various NDT techniques are discussed along with advantages, disadvantages and various factors that affects the accuracy of readings.
Schmidt’s rebound hammer developed in 1948by an Ernst Schmidt a Swiss engineer for testing concrete. When a sledge strikes surface, the degree of bounce back indicates hardness of material. It comprises of a spring control hammer that slides on a shaft. Hammer strikes up to the shoulder of plunger and it bounce back. The rebound distance travelled by a spring control mass is called the rebound index or number andis measured on a scale which is attached to a rider. Fig. 1 shows the working principle of rebound hammer. It is seen that, concrete with low strength absorbs more energy to yield in a lower rebound number and vice-versa. The standard guideline for RH are presented in IS 13311-2005 (part 2) [1].
