In times like today, where rapid construction of buildings and other structures is taking place, there is hardly any land left for new construction, other than the option of conversion of agricultural fields. Though adapting the old and abandoned structures for new uses might be the best practice, yet not everyone follows it and ends up demolishing structures to build new ones. Demolishing can have several negative impacts if not carried out properly. Therefore, the whole process of demolishing, categorizing the waste materials, understanding how different materials can be reused, recycled, repurposed becomes completely necessary to minimize the impact of such activities. 

1. Construction and Demolition (C&D) Materials

Before skipping onto what can be done with the demolition waste of a building or structure, it is rather important to first understand what is meant by demolition materials and the waste generated by them. These types of materials are categorized as ‘Construction and Demolition Materials’ or otherwise known as C&D Materials. These mostly consist of the debris that is generated during the various stages of a building or structure, i.e. construction, renovation, and finally demolition. The waste contribution is mostly because of the demolition of structures and these are often heavy, bulky, and of high density that is often neglected and dumped in a landfill causing an enormous amount of negative impact on the environment. Though the brighter side of this is that each of these materials is highly recyclable and can be reused in various ways if retrieved properly during the demolition phase. 

Where does the construction material from demolished building go? - Sheet1
Waste materials generated after demolishing structures ©

2. Deconstruction – Salvaging valuable Materials

Even though demolition of an existing structure may not be the best practice, yet if done so, it should be carried out properly to minimize its impact as much as possible. Deconstruction is one method that allows salvaging the useful materials during the demolition phase. This involves the careful removal of different materials or parts of a structure for it to be reused in other construction projects. Deconstruction is a substitute procedure for building removal that extends environmental and economic benefits. These advantages include lower building removal costs, diversion of the structure into reuse and recycling, and reduced impact to the site where it is being demolished. Another benefit of this practice is that it helps in removing and separating the hazardous materials from the valuable ones at an early stage. Thus, it becomes important to identify the different categories of materials that can and should be deconstructed carefully for future use. 

Where does the construction material from demolished building go? - Sheet2
Salvaging Valuable Materials ©

3. Classification of Materials to be Deconstructed

The five most common construction materials found in a building are steel, glass, concrete, brick, and wood. These materials found in bulk can be recycled and reused in manifold ways if procured correctly. Though there are other materials as well which are a part of a building and can be reused, yet all these must be differentiated from the components that cannot be used or might be hazardous for its future use. Hence, segregation becomes important. Further, it is vital to know some basics on how these materials can be repurposed again, and here is a brief description of it. 

Where does the construction material from demolished building go? - Sheet3
Different materials of a building that can be recycled and reused ©
  • BRICK – Once the brick blocks are removed, they should be cleaned, sorted, and any contaminants should be removed for them to be used again in construction. Another way is to crush them into rubble and use them as an aggregate for road construction. 
  • CONCRETE – Concrete if retrieved without reinforced steel bars can be valuable and broken down into rubble. This can be sold to the material producers in the market for them to use the rubble in the manufacture of road pavers and other similar products.
  • STEEL – Metals like steel, copper, and brass can be valuable commodities if recycled. These can either be sold as scrap or reused as structural elements on site. Metals are first collected, sorted into categories if necessary, and then shredded. It is then melted and purified to repurpose it into a vast array of fixtures, appliances, furnishings, etc.
  • GLASS – Unlike other materials, glass can get a little difficult to salvage and be a little hard to keep the whole when storing it. But if it undergoes a process of crushing, screening to remove contamination, sorting, washing, and drying, then it can be used for almost anything.
  • WOOD – The difficulty with wood is that though it may be reused, yet any screws, nails, or the condition of the wood can be a challenge. If the wood is in good condition then it can be recycled and be used in particleboard, coverings, pathways, etc.

4. What can be done with the C&D Materials?

Instead of throwing away and dumping the waste generated from demolishing a structure, other ways should be opted to divert the waste and put it to good use. 

  • REDUCING MATERIALS USE – The initial step is to start with the reduction of use materials during the construction phase so that less waste is generated later. Also, during the deconstruction, it should be done carefully so that waste is sorted accordingly and put to different uses. Other examples of C&D source reduction include preserving the existing buildings rather than building new ones or when to adopt construction methods that later allow the disassembly of materials easier. 
  • SALVAGING AND REUSING WASTE MATERIALS – As mentioned earlier, deconstruction is the best practice to salvage the materials carefully so that they can be repurposed. This method is efficient as it maximizes the recovery of materials, diverts the demolition debris from landfills, etc. The only consideration is to understand what materials are in good condition to be reused in other ways. 
  • RECYCLING AND REBUYING – Though some materials can be reused easily, some need to undergo the process of recycling for them to be sold to the manufacturers for use in various products. Materials like asphalt, concrete, and rubble are often recycled into aggregate or other concrete products. 
Where does the construction material from demolished building go? - Sheet4
Image 4 – A Dutch House built using salvaged Billboards and Umbrellas ©

5. Benefits of Minimizing the Disposal of C&D Materials

  • Economically, minimizing the disposal of waste and reusing it reduces the project’s disposal costs and even reducing the cost of buying new materials for new construction.
  • If the materials are recycled on-site, it further reduces transportation costs.
  • Reusing C&D materials helps save some natural resources, which otherwise would have to be mined again from the earth.
  • The common disposal of waste generated from construction sites usually ends up in a landfill. Thus, reusing and recycling leads to fewer disposal and hence reducing the associated environmental issues. 
  • To carry out activities of recycling, reusing, etc. are not easy and specialists are required. This opens more job opportunities for employees working in this field.
  • Another benefit of reusing old materials is avoiding the need to manufacture new products and hence minimizing the overall energy demand required for the extraction of new materials.

A recent graduate who is always looking for creative opportunities and has a strong passion for writing. She is also a firm believer that in times like today, we as architects must show our creativity not by demolishing old structures, but rather adopting the old ones with new uses.