Aerogels as high-performance aggregates for lightweight concrete – working principle and possible areas of use

Figures: Hub, Knippers, Zimmermann, Degner

Interaction of the three different heat transport mechanisms

Figures: Hub, Knippers, Zimmermann, Degner

$2Various particle-size fractions: 4.0-1.0 mm (left), 1.0-0.001 mm (centre), and 60-5 µm (right)$

Various particle-size fractions: 4.0-1.0 mm (left), 1.0-0.001 mm (centre), and 60-5 µm (right)

Slump tests in the test form on the vibrating table

Tested compressive and flexural tensile strengths of the modified aerogel concrete

Two-plate test device with sensor on a carrier film (left) and inserted specimen with surrounding insulation (right)

Comparison of thermal conductivities l_10,trof selected air-based lightweight concretes and concrete with aerogel aggregate

Test set-up with inserted specimens to determine freeze-thaw resistance at the Stuttgart Materials Testing Institute

Sandblasted lightweight concrete specimen with white cement

Polished concrete specimen (anthracite pigment) with embedded light conductors

Development of deformation due to shrinkage

Aerogels have superior thermal insulation properties and are permanently hydrophobic. In a research project, a lightweight concrete was developed that provides significantly enhanced heat insulation properties compared to air-insulated lightweight concrete.

Macroporous lightweight concretes whose insulation effect relies on the ratio of air voids within the material are subject to physical limitations that have largely been exhausted by currently used building materials. One of the options to achieve a quantum leap in the thermal performance provided by lightweight concrete is to use aerogels as concrete aggregates. Hydrophobic aerogel particles have a thermal conductivity that amounts to just 50 % of the thermal conductivity of air. Silica aerogels that are predominantly used for this purpose are composed of a mineral grid and have a pore volume...