Selective demolition of buildings containing asbestos and bitumen sheathing

In 2021, we acquired a 27,300-square-metre property compendium in which there was a complex of buildings of various types and different construction vintages. The purpose of the acquisition was to be able to use the area for a new industrial, artisanal or logistical destination.

The complex consisted of a set of structures built between the 1960s and 1980s where machines for developing and printing photographic material were produced.

The buildings had a total volume of about 84,000 cubic metres and were made of steel and reinforced concrete, with a significant presence of asbestos cement sheets and bituminous sheaths. The work carried out by Gesteco consisted of the demolition of all structures, including foundations, in the area.

After a thorough initial inspection, our specialists found that all buildings needed to be cleared of furniture, portable equipment and stock still present on the site.

Taking samples

Several samples of the materials found (sheathing, insulation, piping) were taken and sent to our laboratory for detailed analysis to identify the different types for subsequent recovery and/or disposal. 

Assessment of structures

The structures were assessed by ascertaining their constituent elements: it was immediately evident that elements of insulation, asbestos cement sheets and bituminous sheathing were present everywhere, mostly in the roofs. The buildings were used as production and storage laboratories and were therefore divided into multiple rooms on several floors. Plant engineering was partially present.  

Site emptying and material separation

It was essential to start with the total emptying of the site.

As it progressed, the demolition had to include the separate handling of the metal plant, such as overhead raceways for the transport of the finished product.

The main task was the careful selection of the different materials from the buildings, sorting them by type to ensure separate handling and thus facilitate recovery and cost reduction. 

Use of special equipment

During the operations, excavators equipped with hydraulic grapples and demolition machines were used, as well as wheel loaders. Thanks to these machines, we divided the work between the activity of removing the installations and internal partitions, and the activity of demolishing the structures.

The personnel on the ground supported each phase, optimising the separation and management of the various materials, maintaining cleanliness and order to ensure efficient waste management. 

Management of elements adhering to other constructions

During the progress of the demolition we had to deal with some delicate situations, such as the need to demolish beams and roofs placed in adhesion to other constructions, without transmission of stress to the structure of the adjacent building. This entailed certain precautions at an early stage or during the drafting of the demolition plan.

Great care was taken to ensure that the complexes were structurally distinct and separate. With the help of stills and videos taken by the drone, it was noted that the beam to be demolished, being in adhesion to the neighbouring structure, could not be demolished by the hydraulic pliers, without running the risk of damaging the neighbouring building, which was also being used for commercial activities during this operation.

In the coordination meeting between all the parties involved, the solution proposed by Gesteco was chosen to proceed with the activity of dismantling beams and roofing with the help of a crane, so as to eliminate any risk of collapse or collapse of structures on the commercial side in operation. 

Special techniques were used, such as vacuuming and bagging the polystyrene used for the internal insulation of all precast panels and floors.

All inert materials from demolition (mainly concrete) were reused after treatment for landscaping. 

Prior to the start of the activity, an in-depth assessment was carried out on the regulatory requirements related to the project.

In fact, the specific work plan for the reclamation of asbestos cement and bituminous sheaths in accordance with Article 256 of Legislative Decree 81/08 was submitted to the competent territorial authorities. This plan is essential to ensure a safe approach during reclamation operations, thus protecting the health of workers and the environment.

At the same time, the necessary communication was submitted to start the inert waste recovery campaign, as required by Article 208, paragraph 15, of Legislative Decree 152/2006 and subsequent amendments and additions, for the use of an authorised crushing plant in order to recover the material produced on site.

The purpose of the documentation prepared was to describe in detail:

• the treatment process adopted, including the types and quantities of waste handled
• the recovery operations carried out
• the assessment of the environmental impacts associated with the activities
• the characteristics of the materials recovered.

Gesteco, thanks to its in-house technical expertise, also managed the entire design and authorisation process for the reconstruction of new spaces that will be used mainly for industrial and logistics activities. 

The Strip-Out

The first phase consisted in performing the STRIP-OUT operation on the different rooms, separating the various types of material and coding them inside the containers for subsequent disposal or recovery.

The purpose of this 'technique' is to prepare the building for total demolition.

Increasingly, this process is the first of the necessary operations. 

Demolition

We started the demolition using hydraulic grapples mounted on crawler excavators, while a third excavator with a bucket handler sorted and separated the material other than concrete for subsequent disposal or recovery.

The primary demolition was conducted sequentially from top to bottom, first removing the metal parts and breaking the reinforced concrete structures into smaller ashlars to prevent sudden collapses of large parts.

The demolition sequence of the load-bearing structures was organised in several stages, proceeding step by step: roof tiles, perimeter walls or roof panels, beams (including internal partitions) and pillars, and continuing with the floor slabs, floors and finally the foundations. 

The asbestos cement sheets and the bitumen sheathing on the roofing tiles and flat roofs were removed before demolition work began. Other materials, such as plaster ceilings and mineral wool on the various floor slabs, were treated in a similar manner.

The excavator followed the demolition phases to handle various types of non-inert materials, sorting them and placing them in containers separated by type, to be then disposed of in specialised facilities.

The foundations were demolished using excavator-mounted demolition hammers or grapples, and the materials were transported to a dedicated area to be subsequently crushed with an authorised mobile crushing plant to obtain 0/80 mm MPS, to be used on site for embankments and fills. The entire demolition operation involved an average of 7-8 men per day and 4-5 operating machines per day. 

Materials Management

In accordance with the provisions of the work plan for asbestos abatement activities authorised by the competent authorities, the work was carried out with the utmost respect for safety regulations.

In the process of separating the various insulators, we adopted special methods such as vacuuming and bagging the polystyrene present inside the prefabricated panels and floors.

Materials not intended for shredding, such as metal reinforcements, metal structures, window frames and glass, were separated, carefully organised in special areas and then placed in dedicated containers.

Thanks to the effective separation of the polystyrene carried out during the demolition stages, using the good practices described above, it was possible to obtain material with the desired characteristics at the exit of the shredding plant.