Deconstruction by mechanical arm, snacking or implosion ? The methods of demolition are many and varied. According to what criteria the contractors should they decide ? Response with experts in the Ginger group who have published a memorandum on the issue.
The demolition of a building is a particular operation for a client. At the time of deciding the method to adopt – deconstruction or mechanical demolition by explosive – it is necessary to take into account different aspects, as highlighted by the experts of the Ginger group, specialists in engineering issues of building and public works. In an article published on their blog, they mention : “If, for security reasons, the demolition of a thermal power plant (…) is always carried out with the aid of explosives, deconstruction mechanical remains the most common method for social housing or industrial buildings“.
- “The demolition of a work may not be undertaken without preliminary studies”, G. Légalle (Ginger CEBTP)
Bar housing or abandoned factory ?
For developers, the first feature to consider is the nature of the building and its configuration and constraints related to the site : the deconstruction mechanics will be preferentially used for housing buildings, in urban centers or industrial plants are located on a production site still in activity. The technique of demolition by explosives is, however, more suited to books of greater height (R+10 at a minimum) or structures non-conventional (power plant) or located at the site forced, to close to roads or public transport links, in order to limit the time of intervention. Other considerations are taken into account, as the stakes and objectives of the operation of demolition.
demolition site © Gregory Noble
If the contracting authority chooses the first option, deconstruction is mechanical, it may wish to consider involving mechanical shovels “big arms”. These machines are equipped with clamps hydraulic designed to capture concrete blocks or scrap metal, or even rock-smasher for concrete very compact. They come and “nibble” building from top to bottom, while remaining themselves on the ground. Ginger says : “If this technique helps to ensure the stability of provisional the work, however, requires conditions of strict security“. The other option, that of proceeding by “clipping“, with the help of a platform installed at the top of the building where you activate the mini-devices of deconstruction that the démantibulent, floor by floor. “This technique allows a better control of falls of materials, “says the engineering group French.
In the case of a demolition by explosives, again, several alternatives are proposed. The simple implosion is to demolish a structure so that it collapses on itself vertically, allowing you to limit the area of impact of materials. As pointed out by the experts from Ginger : “This method requires a technical know-how, in-depth, extensive knowledge of the structures, and this whatever the material, and an organizational rigour, safe and specific“. Implosion slow, for its part, will be more appropriate for buildings that have elongated, such as bars, HLM. Finally, for some of the buildings of private persons, the contracting authority may opt for the failover that involves placing explosive charges at the foot of the building, in order to guide it in its fall. The use of this technique is justified by the presence of industrial machinery of large size, such as boilers of more than 2,000 tons, suspended structures and impossible to put into security during a deconstruction classic.
- Demolition blasting of the last vestiges of the thermal plant in Ambès
- Ginger CEBTP Demolition certified MASE
Ginger concluded : “The demolition of a structure is not trivial, it is useful to remember that it cannot be undertaken today without studies specific prerequisites, to meet precisely the objectives of the employer, and that it must be carried out in compliance with the regulations in force“.