New Zealand demolition companies like Chemcare use many different demolition methods to achieve their destruction, wrecking, dismantling, and razing goals, such as manual, mechanical, controlled, chemical, and selective.

While a combination of machines and manpower is effective for demolishing buildings so new ones can be built in their place, explosives can also be practical. If you’re weighing up your demolition options for your next development project, it can be worth learning more about explosives. You might then learn whether this demolition method is right for you.

 

What Are Explosives?

Explosives are one or more substances that can react to light, heat, sound, and gases. There are at least two known explosive types: high-order and low-order, and these serve different purposes.

High-order explosives release energy immediately and destroy objects in their path with a shockwave breaking through the sound barrier. In contrast, low-order explosives release their energy slower while releasing gas.

You might see low-order explosives more commonly used in fireworks displays, while high-order explosives are popular in demolition, perhaps in conjunction with regular demolition tools.

 

Who Can Use Explosives?

Explosives can tear a building apart in seconds, so the average New Zealander can’t walk into a shop and purchase them. In fact, only approved handlers with controlled substances licences are allowed to buy and use explosives for demolition.

Those needing to use explosives must be an improved handler of explosives for construction blasting, as outlined in the HSNO Approved Code of Practice. To become an approved handler, they must show competency in:

• Storing explosives

• Understanding the explosives and their properties

• Designing blasting layouts and performing blasting operations for construction work

• Manufacturing ANFO explosives

• Demonstrating knowledge of blasting layouts for specialist blasting techniques

Approved handlers must also have at least six months of experience using explosives in the construction industry, a minimum number of shots (20 within 24 months), and the 20645 or 20333 unit standards.

 

What Explosives Are Used in Demolition?

When you see a building razed with explosives, it’s clear to see they’re effective. But what on earth could tear building materials apart so easily? Every business and country is different, but mines, quarries, and some demolition and construction businesses use ammonium nitrate/fuel oil (ANFO).

Traditionally, black powder and dynamite were also used for drilling and blasting, and businesses might also use shock tubes, ignition charges, initiation devices, boosters, and detonators with different chemicals to get the job done.

 

What Are the Health Hazards of Demolition Work?

Demolition might look like a straightforward job, but it’s not. Aside from complex plans having to be established to keep neighboring buildings safe, demolition workers must also combat a variety of health hazards, such as:

• Dust and non-toxic airborne particles

• Asbestos dust

• Toxic fumes from galvanised steel gas cutting

• Synthetic mineral fibres

• Lead

• Polychlorinated biphenyls

• Silica

Fortunately, many of these hazards can be combatted with adequate PPE and hazardous material removal before demolition.

 

What Precautions Should You Take When Working With Explosives?

Working with explosives can be dangerous, which is why only skilled, experienced, and qualified people are typically tasked with this job at reputable demolition companies. During the explosion or implosion process, key structural members are cut or disintegrated by drilling holes with explosives. Sometimes, companies also fix plaster charges to the outside.

If this method is preferred, demolition workers must:

• Ensure an approved explosives handler is in charge

• Consult an IPENZ-registered engineer to ensure it’s a feasible plan

• Give a demolition plan to the Department of Labour health and safety inspector

• Be aware of strong columns that might make a building sit rather than topple

• Use small charges and mats to prevent debris from flying

• Notify the New Zealand Fire Service

• Advice local authorities and the New Zealand Police of your demolition proposals

• Establish safe escape routes

• Ensure the general public is at least 200m from the blast site

• Advise all employees of the evacuation plan

• Have procedures in place for misfire

• Use electric shot firing

• Be aware of shock damage from detonating fuse

 

It’s also important to be aware of the environmental effects, such as:

• Shock vibration effect on neighbouring properties

• Structural stability of overhead and underground services

• Flying debris damage to neighbouring buildings

• Dust and airborne particles

• Rubble spread

• Traffic management and control

 

 Rely On the Experts For Your Next Demolition Project

There is much involved in the average demolition task, especially when explosives are your preferred method. If the time has come to get started on your next demolition task, call in the experts to assist. They can handle all parts of the demolition process from start to finish, whether it involves explosives or another common demolition technique.