Demolition And More
Brownfield site demolition can present a host of different disciplines and challenges in both demolition and remediation.
In areas where preservation of the “green belt” is rigorously pursued, brownfield demolition and regeneration is vitally important, and given the obvious proximity of utilised structures, houses, offices, shops etc. it can be a highly scientific and hi-tech affair.
Demolition waste is often bracketed with construction waste, both often containing the same or similar elements. Modern construction is beginning to recognise and reduce the levels of waste and improve resource efficiency.
Both construction and demolishing come under the Revised Framework Directive from the EU which came into force in December 2008.
The Directive instructs the UK to devise and employ waste prevention programmes that by 2020, will ensure that 70% of all construction and demolition waste will be recycled and reused.
Demolition carries its own protocols which are addressed when subject buildings are at, or approaching, the end of their lives. A recovery index will list the percentage of building elements, products, or materials to be reused or recycled, and the percentage of these which can be utilised in the new build.
It can go as far as requesting a description of how carbon benefits can be estimated and realised by reduced haulage activities.
No one demolition project is the same as the other, and they range hugely in varying levels of simplicity or complexity, even what appear to be the simplest demolitions, say, single storey housing, can bring issues of asbestos or sewerage, which is why thorough site investigation is catalogued.
In straight forward low level demolition, bulldozers or loaders with steel lances can demolish walls, and excavators or backhoes fitted with hydraulic hammers can break down concrete piles and flooring.
The higher the building the more complex it can become to level it, particularly if it has neighbouring buildings, which on brownfield sites is often the case. Here explosives can only be used in restrictive circumstances, and the demolition is more likely to be piecemeal.
This is often achieved by semi-autonomous machinery removing one internal storey at a time, from top to bottom leaving the exoskeleton to collapse in on itself.
In the quest for recycling and material reuse, on larger sites, specific recycling machinery can be temporarily installed, such as concrete crushers, which can reduce concrete to aggregate to be used again.
Steel and wood are both perfectly suited to recycling for reuse in onward stages of construction.