Skip to main content

CROSS Safety Report

Unstable concrete blocks

Report ID: 174 Published: 1 April 2010 Region: CROSS-UK

This report is over 2 years old

Please be aware that it might contain information that is no longer up to date. We keep all reports available for historic reference and as learning aids.

Overview

A reporter from a consulting firm was called to a site where the blocks in a retaining wall were found to be expanding and falling apart.

Key Learning Outcomes

For the construction team:

  • It is good practice to procure blocks (and other materials) that comply with British Standards from a manufacturer who can give a quality assured history of the product and its constituents

  • Quality control and competent supervision on site can help to ensure that the structure is built in accordance with the design

Full Report

Find out more about the Full Report

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others. If you would like to know more, please visit the reporting to CROSS-UK page.

A reporter from a consulting firm was called to a site where the blocks in a retaining wall were found to be expanding and falling apart. After consultation with an expert, it was decided the cause was most likely to be faulty aggregate that was expanding when wet. Having established that the client was not to blame for the faults the reporter had no further input in this case.

The firm was however subsequently asked to look at a site where concrete blocks from the same manufacturer have been used in a 2m high retaining wall, precast concrete floors and 2m deep foundations to the internal walls of two of the houses.

The blocks used in the retaining wall were showing the same problem as seen in the initial job. The image (Figure 1) is of one of the remaining pallets on site illustrating blocks that have been soaked after a period of wet weather.

Image
Figure 1: cracked concrete blocks

Expert Panel Comments

Find out more about the Expert Panels

Expert Panels comment on the reports we receive. They use their experience to help you understand what can be learned from the reports. If you would like to know more, please visit the CROSS-UK Expert Panels page.

This looks like a severe case of reactive aggregates where blocks are completely breaking up. This type of progressive cracking can occur when there is a high moisture contents (e.g. blocks get wet on site during storage or in a partially constructed situation). It emphasises the point of procuring blocks (and other materials) that comply with British Standards from a manufacturer who can give a quality assured history of the product and its constituents. Once built in it is very difficult to rectify these situations. The standards which apply depend upon the application for which the blocks are to be used. CROSS is keen to hear of similar examples in order that a broader picture may be established.

Share your knowledge

Your report will make a difference. It will help to create positive change and improve safety.

Our secure and confidential safety reporting system gives professionals the opportunity to share their experiences to help others.