Institute of Fundamental Technological Research

In recent years, the construction industry has developed an ecological direction, which aims to use natural materials. These materials can be both vegetable and animal origin. Building structures made of such semi-finised products are usualy light, non-destructive for environment, and in many cases made of recycled materials. Such an eco-building model often does not require energy inputs for production. It contributes to the development of energy-saving investments which meet the current technical requirements. These materials can perform an insolating function, like sheep's wool or cellulose, as well as construction or finishing function made of products like plywood, fibrous materials with an external gypsum or wooden panel or clay plaster with straw. Such products are perceived as healthy and cheap, and in many cases available locally. These solutions can have a significant impact in modern construction due to the increase in the prices of traditional construction products and energy savings during construction and investment use. The article aims to provide basic information about selected materials of natural origin and compare them in terms of hygrothermal research.

Hemp-lime bio-composite (hempcrete) is a new building material consisting of two main constituents: hemp shiv and lime-based binder. Hemp shiv is a woody core of Cannabis Sativa plant obtained in decortication process and chopped into particles. Lime-based binder is a mix of binders with highest content of hydrated lime (other ingredients often present in a mix are: natural hydraulic lime, pozzolans, cement and others). Its natural origin, ability to crate healthy indoor environment, good thermal properties and especially high ecological values (including low carbon emission in the entire life-cycle) makes it an sustainable alternative to commonly used materials in construction industry. Due to its mechanical properties hempcrete is not a load-bearing material. It is used as a filling material for single-layer walls with a structural frame and as an insulation material for existing walls, floors and roofs. Construction techniques include forming monolithic walls by compacting the mix in a formwork, spraying, bricklaying from precast blocks and prefabrication of entire wall elements. In this paper the results of mechanical and hygrothermal properties of the developed hemp-lime composites will be presented. The results will be used to obtain the hygrothermal characteristics of the building partitions applying numerical simulation methods.