CO2 neutral, hemp-lime concrete, pozzolans, pre-compression
Abstract
To answer different problems set by the 21st century, European Union is constantly updating the old and adapting new directives and regulations. One of these directives is 2010/31/EU as a piece of Energy package which sets forth a goal to reduce primary energy use by 20% and to achieve 20% reduction in greenhouse gas emissions by 2020. It also sets a task for all buildings built after 2020 to be zero-energy buildings. To achieve these goals, next to existing building materials, a new, innovative, and more sustainable materials needs to be studied and implemented. One of these possible materials is lime-hemp concrete – a self-bearing thermal insulation material that consist of lime and hemp shives. Its mechanical properties seem promising, and thermal conductivity below 0,08 W/m*K is significant result for a material that sequesters more CO2 then is created in its life cycle. In the paper an effect of pre-compressed of hemp-lime mix before curing is studied. Two different binders were chosen (dolomitic lime and dolomitic lime with metakaolin) and three different compaction ratios – 50, 25 and 0 %. As expected, the compaction has a direct impact on compressive strength, as well as flexural. The elevated densities also have a negative effect on thermal conductivity, yet not as much if the same density would be achieved with addition of more binder. This method could help to produce lime-hemp concrete materials with better strength/thermal conductivity ratio. A further research of improved drying techniques is needed, as the samples had softer inner part, due to excess moisture during curing.
