Analysis of the Variation in Different Nondestructive Testing and Standards

Abstract

Non Destructive Testing (NDT) methods are used to review or measure the materials or designs without annihilating their surface, item uprightness and future handiness. The overall objective of the research is to assess the strength of concrete in existing structures using Nondestructive Tests at Kachankawal Rural Municipality, Jhapa District of Nepal.Rebound hammer test and ultrasonic pulse velocity tests were used for determining the compressive strength of concrete. The existing Reinforced Concrete Cement culverts were used for 9 existing structures. Average rebound number were taken and calculated from each sample. From the average rebound number were taken to determine the grade of concrete along with corresponding compressive strength. Similarly, the Ultrasonic Pulse Velocity tests were done on same existing structures and path length and time were noted for assessing the corresponding compressive strength and the quality of concrete. Triangulation among rebound hammer test, ultrasonic pulse velocity test and proposed initial grading were validated using chi square test. Relation between compressive strength with rebound hammer and ultrasonic pulse velocity were analyzed using linear regression model. Chi square confirms variation in compressive strength between calculated compressive strength and standard compressive strength. The relation of compressive strength (y) at R² = 1 with rebound number (x) and ultrasonic pulse velocity (x) could be expressed as y = 0.9306x - 2.7233 and y = 2.904 x + 10.119 respectively. The study is a guiding tool for concern authority and professionals to make effective decision regarding further structural development and budget allocation of the existing structures.