---
title: "Destructive and non-destructive tests"
subject: "Building Technology"
chapter: 11
key: "semester_6/building_technology:retrofit-destructive-tests"
source: https://www.bctengineer.com/q/semester_6/building_technology/retrofit-destructive-tests
site: BCT Engineering
---

# Destructive and non-destructive tests

Building Technology · Chapter 11: Earthquake protection & Retrofitting in building

- Asked in: 2078 Baisakh, 2 marks
- Video: [Destructive VS Non Destructive Testing. What is Material Testing?](https://www.youtube.com/watch?v=kxU1hf5Be78) — Quality HUB India
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_6/building_technology/retrofit-destructive-tests
- Whole chapter: https://www.bctengineer.com/md/semester_6/building_technology/chapter-11

## Question

Why are destructive and non-destructive tests in building carried out?

## Short answer

Tests assess actual strength, condition, and hidden defects before retrofitting. Destructive tests like core cutting give direct strength but damage members; non-destructive methods such as rebound hammer and ultrasonic pulse velocity evaluate quality without damage. Both are combined for reliable data.

## Answer

Tests on existing buildings are carried out to assess the **actual strength and condition** of materials and members before deciding repair or retrofit, check quality of construction, find hidden defects (voids, corrosion, cracks), and decide whether the structure is safe.

- **Destructive tests** (core cutting, rebar sampling, load test to failure on samples, brick/mortar samples) give direct strength values but damage the member.
- **Non-destructive tests (NDT)** (rebound hammer, ultrasonic pulse velocity, cover meter, half-cell potential) assess the strength and quality without damage and can be done at many locations.

Both are often combined: NDT for wide screening and a few cores for calibration, so retrofitting is designed on real data.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Why are tests done on existing buildings?
   A. To assess actual strength and condition before deciding repair or retrofit
   B. To increase concrete strength
   C. To avoid any design
   D. To paint the building
   Answer: A. Tests give real data about material quality and hidden defects. (Key point: Purpose)

2. What is a feature of destructive tests such as core cutting?
   A. They never damage the member
   B. They give direct strength values but damage the member
   C. They give only surface hardness
   D. They are done at hundreds of points
   Answer: B. Destructive tests are accurate but harm the member. (Key point: Destructive tests)

3. How are NDT and cores combined?
   A. Cores everywhere, NDT never
   B. NDT only after demolition
   C. NDT for wide screening and a few cores for calibration
   D. Neither is calibrated
   Answer: C. Combining gives wide coverage with direct calibration. (Key point: Combined use)

## Related in Building Technology

- [Non-destructive tests in buildings](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Andt-building) — Building Technology, chapter 11
- [Setting out of a building](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Asetting-out-building) — Building Technology, chapter 2
- [Principles of laying out water supply system](https://www.bctengineer.com/question.md?key=semester_6%2Fbuilding_technology%3Awater-supply-principles) — Building Technology, chapter 12

## Related in other subjects

- [Non-destructive tests on insulators](https://www.bctengineer.com/question.md?key=semester_8%2Fhigh_voltage_engineering%3Anon-destructive-insulator-tests) — High Voltage Engineering, chapter 7, asked 4×
- [Destructive and non-destructive tests in masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adestructive-ndt-masonry-list) — Concrete Technology and Masonry Structure, chapter 10
- [Non-destructive tests for masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Andt-masonry-tests) — Concrete Technology and Masonry Structure, chapter 10, asked 3×
- [Destructive tests of concrete](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adestructive-tests-concrete) — Concrete Technology and Masonry Structure, chapter 5