Expanded clay aggregate

What is Expanded Clay?

Expanded clay is a lightweight and porous material obtained through high-temperature firing of specific types of clay, which expand and form a structure similar to small granules or balls. This process transforms the clay into a material with excellent insulating properties, both thermal and acoustic.

 

Technical Characteristics

Expanded clay has a low specific weight, making it ideal for applications where weight is a critical factor. It has good thermal insulation capacity, with thermal conductivity values varying according to density but generally around 0.08-0.11 W/mK. It is also breathable, which helps control humidity in buildings, and has good fire resistance.

Use in Construction

Expanded clay is widely used in construction for various purposes. It is used as a lightweight fill material under floors, specifically for creating so-called "subbases," the layer beneath the cement screed. Apart from lightening structures, it is used as thermal and acoustic insulation in roofs, floors, and walls. It is also utilized for making screeds where lightness is required (necessary in renovations where floors have limited load-bearing capacity) and to enhance the energy efficiency of buildings. Creating subbases and screeds with expanded clay allows for reduced weight and improved insulation performance. Additionally, it is used in green roofs or roof gardens to provide drainage and insulation.
 

Application Methods

For application, expanded clay can be spread in uniform layers on flat surfaces, like floor subbases, where it is then compressed and leveled. For roofs or floors, it can be laid in bags or as loose granules, often combined with waterproof membranes or sheets to prevent leaks. In plasters or screeds, it is mixed with cement or other binders to form an applicable paste on vertical or horizontal surfaces.

 

Problems and Disadvantages

One of the challenges in using expanded clay is related to its handling; the granules can be dusty and require precautions during installation to prevent respiratory issues. Additionally, if not properly laid, it may not provide uniform insulation, leaving room for thermal bridges or moisture problems. Cost can also be a factor, although it varies depending on the type and quality of the expanded clay.
Expanded clay is not suitable for environments where very high mechanical resistance is needed, such as in structures that must bear heavy loads without deforming. Moreover, it is not the ideal choice for situations where total waterproofing is required, since, despite its breathability, it is not completely impermeable. In contexts where humidity might be excessively high without proper ventilation or barriers, expanded clay might not be the best solution due to its water absorption capacity.
 

Clay and Sustainability

Expanded clay is a natural material, and its production process involves relatively low energy consumption compared to other synthetic materials. It is recyclable and can be reused, enhancing its sustainability profile. The use of expanded clay also contributes to reducing the weight of structures, thereby decreasing the environmental impact associated with heavy construction materials.