Cement-based renders with insulating properties

•The technology of an insulating render based on simple and cheap materials.•The combination of techniques to record specific properties of the render.•Contribute in order to find ways to reduce the cost of buildings’ insulation.

The functional role of renders as a mean to protect structures by increasing their resistance to weathering was known even from prehistoric times. Through centuries the demands in construction were increased as functional, aesthetic, economic and insulating criteria had to been fulfilled. Into this frame, renders had to play a malty-phase role. In the present work a series of renders were produced based on white cement and lime and three different aggregate types were tested in order to achieve a render with insulating properties. The insulating capacity was characterized by the thermal conductivity (λ) measurements. The aggregates were silica sand, glass particles (laboratory produced from recycled bottles) and glass-spheres. Mechanical, physical, micro-structure properties were recorder and thermal conductivity was measured. As a result, renders with λ of 0.3 W/m K were produced and this could be considered as a material that can contribute to the thermal insulation of buildings.