Use of Lightweight Filling Materials

Use of Lightweight Filling Materials to Increase Thermal Insulation It is very well known that in most countries, energy use in the building sector represents about one third of the total energy consumption. Moreover, in developing countries the residential building sector accounts for more than half of the electricity consumption. The economic growth is expected to boost residential demand for electricity, such as electric lighting, air conditioning in order to keep the comfort properties. For such reason, the energy consumption for residential shows an increasing trend worldwide and is of the key concerns over the world. In addition to increasing electricity demand, rising energy costs and pollution levels, there is real concern with the quality of indoor air when using heaters or air-conditioning equipment. Moreover, for developed and developing areas it is known the heat island effect (urbanized areas that experience higher temperatures than outlying areas) has become a serious problem. In the construction industry, different kinds of systems are gaining traction for improving the thermal insulation properties of buildings. On one side, it is already a megatrend in some countries the use of elastomeric coatings for roofing applications. Cool roof coatings are white or special reflective pigments that reflect sunlight. These coatings are like very thick paints that can protect the roof surface from ultraviolet (UV) light and chemical damage, and some offer water protection and restorative features. Products are available for most roof types and applications improving some comfort properties like reflectivity (roof surface's ability to reflect rays from the sun) and emissivity (the ability of a roof to re-radiate any energy absorbed back to the sky), both key properties for keeping the building comfortable. A coating which maintains its solar reflectance and emittance will keep a building cooler and could lower energy costs by reflecting away heat from the sun. These properties (reflectance and emittance) can be enhanced by using engineered lightweight fillers like closed-cell expanded perlite. In facades and interiors, the use of thermal insulation renders and plasters are well known as an effective mechanism for reducing thermal conductivity, defined as the rate at which heat transfers through a material with a given temperature gradient. The thermal conductivity of a material is a measure of its ability to conduct heat. By reducing the thermal conductivity, better insulation properties are expected. There are several systems in the industry for reducing thermal conductivity, such as lightweight insulation mortars. Light-weighting is an established global trend in a variety of industries and applications. It makes manufacturing products and living in our world easier. Conveniently, formulators can achieve light-weighting by adding specifically engineered fillers to their recipes. For building professionals, lightweight fillers offer great potential to support improvements in product properties, especially weight, and application procedures, which expands the comfort zone for people. The utilization of lightweight fillers is already common in many construction applications like spackles, joint fillers, tile adhesives, plasters, renders, levelling compounds, and thermal insulation mortars, whereas the required characteristics of the used lightweight filler may differ significantly, depending on the final formulation and performance of a product. One of the lightweight filler materials with better insulation properties is closed-cell expanded perlite. It is well known that expanded perlite has been used for decades for insulation purposes, but it is necessary to differentiate between two different types of expanded perlite available on the market: the traditional open-cell, and engineered perlite based on closed-cell. When comparing both materials, it can be seen how different both materials are. The higher hermiticity, spherical morphology and higher compressive strength of closed-cell expanded perlite make it a more suitable selection for insulation properties when compared to traditional open-cell expanded perlite (flake shape, non-closed structure and negligible strength). Moreover, closed-cell expanded perlite leads to lower water demand. [caption id="attachment_139521" align="aligncenter"] Lightweight Filler Based on Closed-Cell Expanded Perlite[/caption] [caption id="attachment_139522" align="aligncenter"] Traditional Open Cell Expanded Perlite[/caption] When measuring the thermal effectiveness of introducing lightweight fillers in insulation mortar, thermal conductivity measurement can provide a clear indication of thermal insulation performance and it can be measured according to standard EN 12664. The principle of the determination of thermal conductivity with the Guarded Hot Plate is to establish through a homogeneous test sample in the form of a plate with plane and parallel faces, a heat flow in stationary mode. The heat flux is obtained by measuring the power supplied to the hot element. In testing carried out in several mixes containing lightweight fillers based on closed-cell expanded perlite, the large impact on lambda (λ) reduction was confirmed, from λ = 1.5 W/mK for reference mixes not containing lightweight fillers down to λ = 0.47 W/mK when using 9% of closed-cell expanded perlite (replacing the corresponding volume of sand when introducing the lightweight filler), meaning that thermal properties are significantly enhanced. Of course, by increasing the dosage rate of the lightweight filler based on closed-cell expanded perlite, the lambda (λ) value can be reduced further. There are some insulation mortars with higher dosage rates of closed-cell expanded perlite (up to 40%) leading to mortar density of ~300 kg/m³ and thermal conductivity λ = 0.05 W/mK.

Summary

Comfort properties (e.g. thermal insulation, solar reflectivity, emissivity) are a real global megatrend in the construction industry and there is a real need to enhance the insulation properties of buildings by reducing energy consumption to make the future more sustainable. The use of lightweight fillers based on closed-cell expanded perlite, clearly differentiated (higher hermiticity, sphericity and strength) versus traditional expanded perlite, leads to lower thermal conductivity of the final insulation coating and/or mortar, allowing improvement of the comfort properties of final systems and specifically improving the emissivity in roof coating applications and leading to significant thermal conductivity (Lambda, λ) reduction in several insulation mortars, allowing reduction of the density of the final system and increasing yield (less material needed for covering a given area). It means that by using closed-cell expanded perlite in these systems, comfort properties enhancement and light-weighting can be achieved, matching two of the key megatrends in the construction industry. Onur Eroğlu Market Development Innovation Director Omya David Gonzalez Global Application Manager Lightweight Fillers Omya