---
title: "Push shear test of masonry"
subject: "Concrete Technology and Masonry Structure"
chapter: 10
key: "semester_5/concrete_technology_and_masonry_structure:push-shear-test"
source: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/push-shear-test
site: BCT Engineering
---

# Push shear test of masonry

Concrete Technology and Masonry Structure · Chapter 10: Testing of masonry elements

- Asked in: 2082 Baisakh, 4 marks; 2080 Baisakh, 3 marks (asked 2 times)
- Video: [push Shear test](https://www.youtube.com/watch?v=8N8PUrqHOxQ) — DIPAK  MANDAL
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/concrete_technology_and_masonry_structure/push-shear-test
- Whole chapter: https://www.bctengineer.com/md/semester_5/concrete_technology_and_masonry_structure/chapter-10

## Question

Explain the push shear test of masonry structure.

## Short answer

A brick is freed by removing the head joint and an adjacent brick; a jack pushes it horizontally along bed joints until sliding. Shear strength τ = F/(2Ab), and cohesion c = τ - μσv (μ ≈ 0.4–0.65) with vertical stress σv from flat jack test. It's a quick, minor-destructive in-situ method for joint shear assessment.

## Answer

The **push shear test** is an in-situ, minor-destructive test to find the shear strength of the **bed joints** of existing masonry, i.e. the cohesion and friction of the unit-mortar interface.

**Procedure**

1. Select a brick in a plain region of the wall (not near openings). Remove the adjacent brick at one end to make room for the jack, and rake out the head (vertical) joint at the other end to free the test brick.
2. Place a small hydraulic jack and load cell in the gap, with a steel plate bearing on the end of the test brick.
3. Push the brick horizontally (parallel to the wall) at a slow, steady rate until it slides along its bed joints. Record the load $F$ at first movement (sliding).
4. Estimate the vertical compressive stress $\sigma_v$ on the joints from the load above (or from a flat-jack test).
5. Repeat on several bricks and take the average.

```text
 wall elevation
 +----+----+----+----+
 |    |  jack |    |    <- removed brick position
 +----+--[F]->[brick]--+   brick pushed along bed joint
 |    |    |    |    |
 +----+----+----+----+
```

**Calculation**

$$
\tau = \frac{F}{2A_b},\qquad \tau = c + \mu\sigma_v
$$

where $F$ is the sliding load, $A_b$ the bed-joint area of the brick (length $\times$ thickness; there are two joints, above and below), $c$ the cohesion and $\mu$ the coefficient of friction (about 0.4 to 0.65, from tests). The cohesion $c=\tau-\mu\sigma_v$ is used in the shear design of the wall.

**Merits:** quick, cheap and nearly non-destructive (only one brick is replaced). **Demerits:** scatter in the results, sensitivity to local mortar quality, and it gives the strength of the joint only.

## Check yourself

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

1. What does the push shear test find?
   A. Compressive strength of brick
   B. Shear strength of bed joints (cohesion and friction)
   C. Diagonal tensile strength of panel
   D. Wave velocity
   Answer: B. It gives the shear strength of the unit-mortar interface in an existing wall. (Key point: What it measures)

2. Which formula applies?
   A. tau = F/(2A_b)
   B. tau = 0.707 P/A_n
   C. tau = K_m K_a p
   D. tau = P/A
   Answer: A. There are two bed joints (above and below), hence 2A_b. (Key point: Formula)

3. How is cohesion found?
   A. c = tau + mu sigma_v
   B. c = tau - mu sigma_v
   C. c = tau x mu
   D. c = sigma_v / tau
   Answer: B. From tau = c + mu sigma_v, so c = tau - mu sigma_v. (Key point: Cohesion)

## Related in Concrete Technology and Masonry Structure

- [Diagonal shear test of masonry wall](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adiagonal-shear-test) — Concrete Technology and Masonry Structure, chapter 10, asked 6×
- [Diagonal shear and push shear tests](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Adiagonal-shear-push-shear) — Concrete Technology and Masonry Structure, chapter 10, asked 6×
- [Flat-jack and push-shear tests](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aflat-jack-and-push-shear) — Concrete Technology and Masonry Structure, chapter 10, asked 2×
- [Elastic wave tomography and push shear tests](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Aelastic-wave-tomography-push-shear) — Concrete Technology and Masonry Structure, chapter 10
- [Compressive and diagonal shear tests of masonry](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acompressive-diagonal-shear-tests) — Concrete Technology and Masonry Structure, chapter 10, asked 2×
- [Compressive strength test of masonry prism](https://www.bctengineer.com/question.md?key=semester_5%2Fconcrete_technology_and_masonry_structure%3Acompressive-test-masonry-prism) — Concrete Technology and Masonry Structure, chapter 10, asked 2×

## Related in other subjects

- [Diagonal shear test and flat-jack test calculations](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Adiagonal-shear-flat-jack-numerical) — Design of Timber and Masonry Structures, chapter 8
- [Seismic base shear of a masonry building](https://www.bctengineer.com/question.md?key=semester_5%2Fdesign_of_timber_and_masonry_structures%3Abase-shear-two-storey-masonry-building) — Design of Timber and Masonry Structures, chapter 7
- [Limitations of direct shear test](https://www.bctengineer.com/question.md?key=semester_4%2Fsoil_mechanics%3Adirect-shear-limitations) — Soil Mechanics, chapter 10
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