Use of Lightweight Filler Materials to Improve Thermal Insulation

Using Lightweight Fillers to Improve Thermal Insulation It is a well-known fact that in many countries, the energy consumed in the construction sector represents approximately one-third of that country's total energy consumption. Moreover, in developing countries, residential building construction accounts for more than half of electricity consumption. Economic growth is expected to increase electricity demand in housing as comfort amenities such as electrical lighting and air conditioning systems continue to be provided. Residential energy consumption, which is showing an upward trend globally, is therefore also one of the most fundamental concerns worldwide. Additionally, the rising electricity demand, energy requirements, costs and pollution levels create serious concerns regarding indoor air quality when using heating or cooling equipment. Furthermore, it is known that the heat island effect (exposure to higher air temperatures in urbanized areas compared to rural areas surrounding them) has become a serious problem for both developed and developing areas. Various system types are drawing interest in the construction sector to improve the thermal insulation properties of buildings. For example, the use of elastomeric coatings in roof applications is already gaining considerable acceptance in some countries. Cool roof coatings use white color or special reflective pigments that reflect daylight. These coatings are fairly thick paints capable of protecting the roof surface from ultraviolet (UV) light and chemical damage, and some also provide water protection and self-healing properties. These products can be used on most roof types, and their application improves certain comfort properties such as reflectance (the roof surface's ability to reflect solar radiation) and emittance (the roof's ability to re-emit any energy it absorbs back to the sky), both of which are fundamental features to maintain the comfort provided by the building. A coating that retains its ability to reflect and emit sunlight will keep the building it is applied to cooler and can play a role in reducing energy costs by reflecting solar heat. These properties (reflectance and emittance) can be enhanced by using specially manufactured lightweight fillers such as closed-cell expanded perlite. The use of thermal insulation plasters and gypsum in building facades and interior spaces is an effective method for reducing thermal conductivity, defined as the rate of heat passage through a material at a specific temperature gradient. The thermal conductivity of a material is a measure of that material's ability to conduct heat. Better insulation properties can be obtained by reducing thermal conductivity. In the sector, various systems exist that are used to reduce thermal conductivity, such as lightweight insulation mortars. The use of lightweight materials is an established global trend across various sectors and applications. It facilitates the manufacture of products and makes our lives easier. Those formulating these materials can obtain lightweight materials by adding specially designed fillers to their formulations. The use of lightweight fillers enables professionals working in the construction sector to support application procedures that provide improvements in product properties, particularly weight, and expanding people's comfort spaces. Lightweight fillers are already widely used in many construction applications such as filling mortars, joint fillers, tile adhesives, plasters, screeds, thermal insulation mortars. However, the desired property of a lightweight filler used can differ significantly depending on a product's final formula and performance. One of the lightweight fillers with better insulation properties is closed-cell expanded perlite. While it is a well-known fact that expanded perlite material has been used for insulation purposes for decades, a distinction should be made between two different types of expanded perlite found on the market: perlite designed based on traditional open-cell and closed-cell materials. By comparing these materials, we can review how different they are from each other. The higher hermeticity, spherical morphology and compressive strength properties offered by closed-cell expanded perlite make it a more suitable choice compared to traditional open-cell expanded perlite for insulation purposes. Moreover, closed-cell expanded perlite reduces water demand. When measuring the thermal efficiency provided by adding lightweight fillers to insulation mortar, thermal conductivity measurement can clearly demonstrate the material's thermal insulation performance and this measurement can be carried out in accordance with EN 12664 standard. The principle underlying the determination of thermal conductivity by the Guarded Hot Plate method is to establish a constant heat flux in steady-state conditions on a homogeneous test specimen in the form of a plate with flat and parallel surfaces. Heat flux is obtained by measuring the power supplied to the hot section. In tests conducted using various mixtures containing lightweight fillers based on closed-cell expanded perlite, it was confirmed that the greatest factor in reducing the lambda (λ) value from λ=1.5 (W/mK) as a reference when lightweight fillers are not used to λ=0.47 (W/mK) is the use of 9% closed-cell expanded perlite (removal of the same volume of sand when adding lightweight filler). Of course, by increasing the dosage ratio of closed-cell expanded perlite-based lightweight filler, the lambda (λ) value can be reduced further. Insulation mortars with higher dosage ratios of closed-cell expanded perlite (up to 40%) exist. This provides approximately 300kg/m³ mortar density and λ=0.05 W/mK thermal conductivity values.

Summary

Comfort properties (e.g., thermal insulation, solar radiation reflection and emittance capability) are highly sought after globally in the construction sector, and there is a real need to improve buildings' insulation properties and make them more sustainable by reducing energy consumption. The use of lightweight fillers based on closed-cell expanded perlite (which is highly differentiated with higher hermeticity, spherical morphology and compressive strength properties) instead of traditional expanded perlite enables the development of the comfort properties of final systems by providing lower thermal conductivity of the resulting insulation coating and mortar, particularly in roof applications by enhancing the coating's emittance capability and achieving significant reduction in the thermal conductivity (Lambda, λ) of various insulation mortars, thereby reducing the density of the final system and increasing efficiency (less material is needed to cover a specific area). This means that by using closed-cell expanded perlite in these systems, two fundamental properties sought in the construction sector—comfort properties and the use of lightweight materials—can be provided. Onur Eroğlu Market Development and Innovation Manager Omya David Gonzalez Global Application Manager, Lightweight Fillers Omya